N6JSX monoband J pole antenna dimensions
A $50 Beverage
by Randall Thompson, K5ZD
Originally printed in the YCCC Scuttlebutt #119, October, 1995
I built my first Beverage this past year. It was so easy I can’t believe I lived without one. Here’s how to do it:
- Go to Home Depot (or other large hardware store) and buy a 500 ft roll #16 THHN or MTW wire. It’s available in every color you can imagine for about $15 per 500/ft roll.
- Go to local feed store and get some electric fence insulators. This cost me about $3.
- Call your favorite radio dealer and order an ICE Beverage matching box. Cost: about $40.
- Go to Radio Shack and get a 400-600 ohm resistor. I actually used four (4) 2K-Ohm, 2-Watt resistors in parallel!
- Roll out the wire in the desired direction. Mount the fence insulators to convenient trees (my Beverage is not perfectly straight) about 7-9 feet up. Connect one end of the wire to ground through the resistor. Connect the other end to the matching box. Connect coax. Enjoy!
I did follow the conventional wisdom of sloping the ends down. I used 4 foot ground rods at each end. I only have room for a 500 foot run. W3LPL has pointed out that 580′ might be a better length. It’s simple to solder some more wire on.
This antenna makes 80 and 160 enjoyable. Less than $50 to hear Europeans all summer on the LF bands seems like a good deal if you have the space!
When the antenna broke this summer, I used a split bolt connector to join the two pieces back together. You can find these for about $1 in the electrical aisle of the Home Depot (or hardware store). No solder required!
Note 2: You can also order an ICE matching-transformer from:
Industrial Communication Engineers, LTD.
Indianapois, IN
Website:Industrial Communication Engineers, LTD.
About 1/2 the way down the above ICE webpage, you’ll see that ICE offers their Model 180A matching box for $39 (plus shipping).
The 180A has taps to select 50 or 75-Ohm coax feedlines, and taps to match 300/450/600 or 800-Ohm Beverage antenna loads.
The 180A also has dc blocking capacitors, and a gas-discharge lightning protection system.
The Lattin 5 band Antenna
The antenna was named for W4JRW who invented it and holds a patent on the basic principle and uses quarter wave stubs, which act as insulators at the frequency for which they are cut.
For example, the 6’11” stub (quarter wave times the velocity factor 0.8 of the feed line used) blocks RF for 28 mhz from reaching the rest of the antenna.
In the example shown in the diagram, tubular foam filled 300 ohm feed line was used, which has a VF of 0.8. Other feedlines may be used, for example, slotted ribbon and the length of the stubs worked out using the correct velocity factor
Building the lattin antenna
This will require some forethought and planning.
Avoid cutting the continuous top wire, which supports the whole system.
I wonder if it might be an idea to use a suitable polypropylene line to support the wire, which may be subject to breaks, especially at the solder points?
A suitable centre piece may be constructed and constructors may want to include a balun at the centre of this balanced antenna, which is fed with unbalanced line (coax).
A version of the Lattin could be designed for all bands, including the WARC bands – get snipping!
Kenwood TS-2000
General overview
From a functional standpoint, the TS-2000 is two transceivers in one box. It is an HF transceiver that incorporates many of the features of the TS-570 and the TS-870 (while adding a few of its own), as well as a variation of the multifaceted TM-D700A. Its delineation is not quite that simplistic, however. The TS-2000 is a complex matrix of transceiver components that allows it to operate as two independent radios in one box. It can allow the user to operate on HF and either VHF or UHF simultaneously, which is something that recent offerings in the arena of 160m to 70cm all-mode radios cannot currently do. It also has the capability of operating as a full-duplex VHF and UHF transceiver for the purpose of working the OSCARs, or similar applications. What is truly unique is the on-board packet TNC that was borrowed from the TH-D7G, which has the ability to transfer data over the air at selectable rates of 1200 and 9600 bps. Tables 1 through 4 show the general specifications of the TS-2000.
Physical characteristics
Kenwood has listed a number of distinctive features in their promotional literature. However, it is my opinion that they have overlooked an important feature that definitely adds value from a consumer perspective: ruggedness. The box that houses the electronics is an aluminum casting. The fasteners are of a good quality, and the machine work is very high-caliber. When viewed in comparison to some radios that come in a thin-walled, spot-welded enclosure, the TS-2000 has extraordinary structural integrity.
The front panel is a stylistic ergonomic design. I found that everything was easily accessed, and functionally well organized. I appreciated the fact that the buttons were not too small for me to control, and that the markings were easy for me to read. Of course, the most important feature of any HF radio is how good the tuning knob feels. This one has all the feel of something superbly machined. There is no wobble that I could detect, and the motion is smooth and easy. The tuning rate is front panel menu controllable at rates of 500 and 1000 Hz-per-revolution. This tuning rate may be reduced by a factor of 10 by depressing the FINE button on the front panel. Did I mention that the tuning knob has a nice feel to it?
The rear panel is also well designed. There is a minimum of clutter. The RF connectors are placed in such a manner as to minimize coax runs from their respective circuit boards. There are two selectable HF ports, as well as a handy RCA jack input for the ham who has a beverage or two that he or she would like to employ. The really nice thing is that the RCA jack is menu-selectable. There is no need to pull the cover off and manipulate a tiny microswitch.
There is a nice feature brought forward from (if I remember correctly) the TS-570. There are two separate CW interface ports. One is the standard stereo jack for the keyer paddles. The other is a direct keying jack that functions in parallel with the keyer. This is really nice when using your favorite contest logging software. You can operate the keying function of the logging software and the internal paddle simultaneously. And I might as well mention it now: There is also a menu item that allows the keyer to override the direct keying port if the operator so desires.
Circuitry overview
As I stated earlier, the TS-2000 operates by the carefully planned manipulation of a matrix of common circuitry, as well as a cadre of dedicated components. For example, the receiver front ends and transmitter power amplifiers operate as common assets for the two receivers. There are, in essence, two independent receivers. One is referred to as the MAIN receiver, and the other the SUB receiver. The MAIN receiver’s frequency is displayed in the prominent central position above the main tuning knob, while the SUB receiver is displayed in a half-sized font to the right. There is an exception to this, of course, as in the case of satellite operation, where the A and B bands may be switched back and forth, and when the MAIN unit is operating in SPLIT mode. It should be noted that even when something other than the SUB receiver’s frequency is being displayed in the right window, it continues to operate normally. This is to say that the SUB function is not suspended when the MAIN section is operating SPLIT.
The audio detection of the various operating modes (other than FM in the SUB receiver) is accomplished in the final IF using DSP. The ability to set the center frequency and width of the IF DSP filter on the fly means that there are no expensive crystal or mechanical filters to purchase. However, since both receivers cannot use DSP detection simultaneously, the SUB receiver only operates on FM and AM. There are a number of audio DSP algorithms available to the MAIN receiver (which will be discussed in a bit). DSP is used in the transmit path as well. This allows the user to program special RX and TX audio characteristics from the main menu. The frequency response of the RX and TX may be tailored to the specific tastes of the operator, or, if you are a kind-hearted soul, to the tastes of the listener at the other end.
There are three RF power amplifiers (four with the 1296 module installed). All three amplifiers run class AB, allowing linear operation on SSB and AM. They are quite rugged as well. The 2m and HF/6m amps shown in Fig. 1 are on the large board on the underside of the radio, and both are capable of 100 watts. The 440 amp is on its own board, and puts out 50 watts. Here is a case where the aluminum casting design comes in quite handy. It functions well as a heatsink, and is cooled by a very quiet fan that is controlled by temperature sensors.
I almost forgot to mention the superb automatic tuner that is included with the TS-2000. This is one of the better ones that I have used so far. While most of the automated tuners intended to drive coaxial antenna circuits are limited to around a 3:1 VSWR, this one is not. It has successfully tuned circuits with an indicated VSWR greater than 6:1. It has its limitations, though, and it will tell you up front. The limit appears to be in the 6:1 range, and will refuse to tune above that. It will also send you a polite “SWR” in Morse code to let you know that the tuning limit has been exceeded (a warning to you “slow-coders” out there – it’s faster than 5 wpm). I was very pleasantly surprised at the speed and range of this tuner.
Back to DSP
Part of the genius of this radio is the way in which it does signal processing. In this radio there is not one, but two independent DSP chips (see Photo J). They both run at a clock speed of 100 MHz, and actually communicate with each other when performing their individual tasks.
I have already mentioned that the operator may select preset frequency contouring for receive and transmit audio from the menu. What I did not mention is that the soon-to-be-released ARCP2000 radio control software will provide the ability to personalize one of those menu items. I hope to have a separate feature on that software in the near future. (I wrote this review during and after the big earthquake here in Seattle, so I didn’t get a chance to review the software.)
As for the IF filters, there are default settings that come up when a given mode is selected for the first time. You may then select the center and width of the filter for that mode according to your own tastes, and the radio will remember that setting from then on. You don’t need to re-enter these settings every time you turn the radio on. For your convenience, the center frequency and filter width are set using two vernier knobs in the lower left-hand corner of the front panel. The front panel shows both analog and alphanumeric displays of the filter settings.
Another aspect of the power of this formidable DSP engine is the ability to reduce broadband noise and coherent interference. The MAIN receiver enjoys two types of noise reduction filters. The first, called NR1, is a linear adaptive filter that is similar to that found in many modern transceivers. What is noteworthy is that the threshold of NR1 mode is front panel selectable, or may be left in the AUTO mode. I have played with this a bunch, and found that leaving it in the AUTO mode works fine for me, especially when working SSB and FM. I should mention that the SUB receiver can employ this filter as well, but only this one.
The others are not available
The second mode is NR2, which is a correlation algorithm that has a variable duration of 2 to 20 msec. This is an excellent filter for CW use, but takes a little time to get used to. I have found that a setting of 8 msec is ideal for the type of CW operating that I enjoy, which ranges in speeds from about 18 to 30 wpm. It also took me a little time to get used to the mechanical artifact sound of the background noise. It sounds more like a babbling brook than the soft hiss of a Collins 73S3. Not to worry, though. It will sound normal to you in no time.
The TS-2000 has three, count them, THREE digital mechanisms for getting rid of those pesky 40m AM carriers and careless tuner-uppers. The first is an automatic notch filter with a variable threshold that can be controlled from the front panel. This is useful if there is some distortion or other modulation characteristics present on the unwanted carrier. There is also a beat-canceler, which leaves the IF passband alone, and removes the note from the audio. It is an adaptive filter that can handle more than one beat note, and will automatically shift frequency in synch with those tones that drift about. If you’re like me and have been frustrated by the efficiency of these types of unwanted tone removers, especially when they work so well at also canceling the station you want to listen to on CW, then fret no more. The TS-2000 also has a MANUAL beat canceler. This is great! I finally have the ability to notch out that nudnik who likes to tune up on me when I am in QSO on CW. What a blessing, and it works very well. And what’s better is that it doesn’t introduce a lot of distortion to the passband like the analog notch filters do.
There are some additional features associated with the DSP engine in this radio, like the vernier control of the AGC, that you can discover on your own.
Additional features
This radio is so feature-rich that if I were to describe all of them, this article would cease to be an operator’s review, and become a rewrite of the operator’s manual. But there are a few that should be mentioned, the first of which is the memory and configuration management capability of the TS-2000. There are 300 memory channels available, which are easily programmable from the front panel. Let me tell you that this is a real blessing. These channels may also be programmed with an alphanumeric name tag (also from the front panel) that facilitates easy recall of just why-in-the-heck I saved each frequency and mode. These memory channels may also be grouped and scanned in 10 subgroups. This is quite handy for segregating the frequent- from little-used channels in the scanning process.
If you are in a hurry, and don’t want to fiddle with programming a specific channel, there is also the QUICK MEMORY function that may be used in the VFO mode, and provides convenient storage of 10 channels for quick retrieval. It has been very handy for me in contests, and in pileup management. It stores things like frequency, RIT settings, operating mode (CW, USB, etc.), and interference rejection modes.
There are also two generic memories for storing the basic configuration of the radio. If you operate the radio as both a mobile and base station, the entire configuration of the radio (all of the menu-controllable items) may be stored for those two operating environments. Another use would be simply to differentiate between primarily CW or SSB operation, or between contesting and rag-chewing. You get to choose, and it’s all commanded by a couple of front panel keystrokes. One of the things that I feel is commendable concerning Kenwood is that fact that they DON’T charge their customers for memory control software, and make it available in downloadable form on the Internet. If you go to the http://www.kenwood.net web page, you can download a program called MCP2000 that allows for simple programming, storage, and retrieval of these formidable memory functions. Figs. 1, 2, and 3 are screen captures of MCP2000. Fig. 2 shows an expanded control panel that allows detailed programming of each memory channel shown in Fig. 1. Fig. 3 shows how each menu memory setting may be programmed without having to go to a separate panel for providing the programming detail. This software is a must. I highly recommend it, and it’s FREE.
Packet terminal node controller
One area where Kenwood has been out front in the development of technology for us radio amateurs is in the inclusion of packet terminal node controllers (TNCs) in their transceivers. They started with a handheld (TH-D7G), and quickly included their flagship dual-band mobile (TM-D700A). They have closed the product line loop with the TS-2000. The TS-2000 service manual states that the TNC is the same one developed for the TH-D7 by Tasco. It appears to me, at least, that this is the same product that has gone into the TH-D7 and TM-D700, and the Alnico DR135TP. Only minor variations in the command set for the TNC in each radio exist. Kenwood’s statement about the derivation of the TS-2000’s TNC appears to be right on the mark. Although there is no obvious way to connect a GPS receiver to the TS-2000, the GPS commands found in the TH-D7 instruction set can be observed when sending the DISP command to the TNC in the TS-2000. I am hoping that a future “blue-wire” mod will come forth from either Kenwood or the general amateur community that will allow GPS interface via one of the unused ACC ports (hint, hint).
The TNC itself is a modest performer, and has been well chronicled in other reviews that feature the radios mentioned above that also have it on board. Interface between the TNC and a PC or laptop is accomplished via a DB-9 serial port on the back of the radio. No high-priced level converters are required. In the case of the TS-2000, the TNC’s function is enhanced by its ability to access the DSP chipset to provide some prefiltering when operating AFSK at 1200 bps. At 9600 bps, the TNC has a direct analog route to the outside world via the FM modulator and discriminator. KISS mode for TCP/IP is included, and I can vouch for the fact that it seems to work quite well at both baud rates. I had an opportunity to test it on the local TCP/IP network that is run by Puget Sound’s WetNet Experimenters Group.
Although the APRS functionality found in the TM-D700 is not included in the TS-2000, there is yet one very unique and useful internal function that it can perform. It is called the Packet Cluster Tune (PCT) function. This is really slick, and it works like this. The user sets the SUB RX to the local DX packet cluster frequency, sets the SUB RX as the data band, and turns on the PCT function. When a packet cluster DX spot announcement is received, the frequency, callsign and other related data appear in the SUB window. The information is also automatically written to the QUICK MEMO pad for later retrieval.
The PCT function may be configured by front panel menu commands to do the following. First, it will provide an announcement to the operator in the form of a beep, a CW recital of the callsign, or (if you have the optional VS-3 voice synthesizer unit installed) a voice announcement of the same. That’s not all. You can also set this function to automatically set the radio to the frequency from the DX spot that is displayed in the SUB window. If that sounds like a potential inconvenience, the radio may also be configured to only change frequency when commanded to do so by depressing the SET button. I showed that function to some of the members of the Redmond Top Key Contest Club, and they got a big kick out of it. I have to admit that I have used that function quite a few times myself. It really helps to keep the traffic density down on the packet cluster channels, as this is a passive feature (meaning it doesn’t require any transmitting). With the dual radio personality of the TS-2000, the monitoring of the packet cluster channel is uninterrupted while carrying on a QSO on HF.
Wrap-up
There is much more that I could write about the features and performance of this radio. I intend to write a separate review on the anticipated ARCP2000 remote control software that is soon to be released with their introduction of the “box” version of the radio. You heard me right. By the time you read this, Kenwood will have released the TS-B2000, which is a blank-faced version of the TS-2000 that may be controlled by the ARCP2000 software on a PC or laptop, and via the R2000 remote control head (borrowed from the TM-D700). In that review, I will also talk a bit about the following features:
- Sky Command II
- Crossband repeat
- Remote control
- Microphone control
- Direct FSK operation
- Satellite operation
- User-defined digital filtering of RX and TX audio
Until then, I encourage you to have a close look at this fine radio for yourself. My neighbor did, and went in and bought one for himself, and he is very critical of radios – their performance and features, that is. That in and of itself is a testimony to the impact that this rig can have on hams who come in contact with it.
The bottom line is that Kenwood has not just produced an excellent radio. What they have done is to further the state-of-the-art in affordable amateur equipment. And I will stand by my assertion that this radio provides a very high level of features and performance for its price, which, by the way, is currently about $2,270 over the counter. When I first heard about its impending introduction, I was certain that the price would easily exceed three kilobucks. Having said that, I believe that the price including the optional accessories such as the VS-3 voice synthesizer, the DRU-3A digital recording unit, the R2000 remote kit, and the soon-to-be-released UT-20 1296 module, will drive the total cost over that mark. However, these are optional items that can be purchased later based on a value-added decision that concerns your own operating needs and desires. The radio as it stands today is quite impressive.
Congratulations and thanks to Kenwood for maintaining their vision, engineering and manufacturing skills, as well as the financial commitment required to continue to provide innovative products to the amateur radio marketplace.
Article originally available here http://elkel.ca/kenwood_a/ts-2000_review!.htm by d r.o l s e n.r i ck
All rights of their respective owners.
7 element Yagi for 20 Meters band
They say if it didn’t blow down it was not big enough, this one was big enough and it did blow, not off but up and over the top of the tower like an umbrella one very windy day in January 1974. I was at work and the XYL called and said the “thing” blew off the top of the tower- WOW, I imagined it in somebody’s living room. In fact it did not blow off it blew over the top, broke in two and slid down about ten feet an hung on the safety cable. When I originally built the thing I rigged this safety line of 3/8 inch aircraft cable from the tower to the four inch diameter boom just in case. I remember I used to laugh when I told people about the safety cable never thinking it would actually blow off the tower. The storm was really a bad one, very high winds with ice covering the boom and elements. In fact a drive in movie screen blew over just down the street from me. It was a very sad occasion, I was the one sad and the neighbors were glad. The obliging neighbors called the building inspector and he was waiting for me when I got down from the top after attaching a rope, disconnecting safety cable and cutting the coax cable and letting it down, smoothly. The inspector notified me that one of my neighbors said that it had blown down three times already this year. This beam worked very well for me for several years.
I apologies for the quality of the photo. Its the only one I have. What you see is what you get. Very narrow beam pattern, that’s not QSB man that’s my beam swinging in the wind.
The omega match was motorized because it was so far out on the boom.
Long Loopstick Antenna
Wound on a 3 foot length of PVC pipe, the long loopstick antenna was an experiment to try to improve AM radio reception without using a long wire or ground. It works fairly well and greatly improved reception of a weak station 130 miles away. A longer rod antenna will probably work better if space allows. The number of turns of wire needed for the loopstick can be worked out from the single layer, air core inductance formula:
Inductance = (radius^2 * turns^2) / ((9*radius)+(10*length))
where dimensions are in inches and inductance is in microhenrys.
The inductance should be about 230 microhenrys to operate with a standard AM radio tuning capacitor (33-330 pF). The 3 foot PVC pipe is wound with approximately 500 evenly spaced turns of #24 copper wire which forms an inductor of about 170 microhenrys, but I ended up with a little more (213uH) because the winding spacing wasn’t exactly even. A secondary coil of about 50 turns is wound along the length of the pipe on top of the primary and then connected to 4 turns of wire wound directly around the radio. The windings around the radio are orientated so that the radio’s internal antenna rod passes through the external windings. A better method of coupling would be to wind a few turns directly around the internal rod antenna inside the radio itself, but you would have to open the radio to do that. In operation, the antenna should be horizontal to the ground and at right angles to the direction of the radio station of interest. Tune the radio to a weak station so you can hear a definite amount of noise, and then tune the antenna capacitor and rotate the antenna for the best response. The antenna should also be located away from lamp dimmers, computer monitors and other devices that cause electrical interference.
Small Loop Antennas
Low profile operating — SMALL LOOP ANTENNAS
Magnetic loops are very effective small antennas. these 3 to 3 1/2+ foot antennas perform close to and in some cases (low mounting heights for one) better than even a small beam. The reason is that a magnetic field is much more concentrated than an electrical one, for example a small horizontal loop at 17 feet performs better (lower radiation angle) than a full size dipole at 35 feet, in fact better for DX than a beam at that height because of the much lower takeoff angle. If you place a beam 1 foot off the ground it will only radiate straight up while a vertical loop will still work DX stations quite well.
This smaller more intense magnetic field also has the advantage of greatly reducing TVI – RFI potential if the loop is more than 15 feet or so away from TV antennas, electronics ect. Another advantage of this magnetic field is the very low background noise heard on the loop because most man made noise is electrical fields. For example if you lived next to a Shopping Mall the loop would not hear all that lighting and power transformers. Also reducing interference is the loops “Hi Q” which means that it receives & transmits on a narrow band range compared to the “full size” antennas.
This effect is very pronounced on the lower bands that the loop will work. I have built several loops and along the way have learned quite a bit about these “little wonders”. Usually I use the parts from one to make the next but my “ugly loop” is one that I keep in service.
While looking thru old QST’s I read up on the Cushcraft R-3 vertical antenna. I made a mental note that the remote controlled variable capacitor looked like it would make an ideal loop component. I found this one on E-Bay for about $25, this was nice considering the most expensive part of the loop is the High Voltage Variable Capacitor and motor drive and controller.The only drawback to this capacitor was the metal mounting (which increases the stray capacitance) and the fact that it was a single stator type not the less lossy butterfly type.
To reduce the losses I directly connected (metal braid) the shaft on the capacitor to the loop itself and polished the capacitor plates to increase power handling. The range of this setup was around 30 thru 180 pf and it will handle 100 watts. I could of reduced the minimum value of the capacitor by eliminating the metal half (future project ?) of the mounting but instead used it as part of the loop. I wanted to test some of the current theories of loop design and this setup was ideal. I built up a PVC frame (easy change of dimensions) and used of all things roof flashing (very thin aluminum) for the loop itself. This cheap material made dimension testing easy, the final size of the loop is 42″ in diameter by 1.6″ wide. One thing that the loop programs (like mloop32) do not take into account is the fact that if the material is too wide it starts acting like a capacitor not just an inductor. This loop is completely assembled with mechanical (nuts & bolts) connections.
This is a big “no no” in loop construction which I used to make testing of different configurations easy and to test that “all connections must be welded” theory. On the air tests, field effects and bandwidth checks have shown that this loop is very efficient until you tune to 40 meters (around 7%), not that surprising since that band is below the theoretical range of a 42″ loop. It sure is fun to stretch it that far and to make 40 meter contacts on such a small antenna. The loop is feed with an 8″ diameter faraday loop not on the centerline (null) of the loop, this is because the capacitance circuit break is on the side of the capacitor assembly.
The pictures show how the control wires are routed “off center” but this is in the null of this loop, if you don’t do this the wires will couple with the magnetic field and detune the antenna. I found very little performance change with the feed loop off center so I left it there for mechanical simplicity. I learned the hard way about the high voltage’s (8,000 V +) in the loop when insulators in the path of RF flow started burning thru (bad) until redesigned. The R-3 controller does a good job of tuning the loop 19 thru 7 MHZ, its meter is a position feedback that lets you know where the capacitor is tuned. A loop like a commercial version like the MFJ “HI Q” Loop (below) or a home brew may have the unique properties that may help you out in your situation.
NOHC Article originally available at www.geocities.com/n0hc
MFJ-940 modification
The MFJ-940 VERSA TUNER II is a useful little antenna tuner for the HF-bands. However it suffers from a minor design error, which can be easily rectified.
As other antenna tuners may show the same kind of “weakness”, the modification described here can be used to improve other types.
The connection between the components in the tuner – coax connectors, switch, coils and variable capacitors are made of rather long pieces of tinned copper wire.
These wires act as small selfinductances. In normal operation stray inductances are absorbed by the tuning components, however when the tuner is switched into “bypass” mode, it affects the 50 ohm match between antenna and transmitter. This is worst on the highest frequencies.
You can check an antenna tuner by measuring the VSWR through of the tuner, when it is terminated by a good 50 ohm load. In my case I could measure a VSWR on 30MHz of 1.8:1 – not very good for a simple bypass!
The solution is to compensate the series L from the wires with parallel C’s. By doing this in the upper end of the frequency range a broadband match can be obtained.
In the MFJ-940 five 15pF capacitors are used. Four from each of the four coax centerpins to ground and one from the switch rotor to ground. This completely tunes out the reactance of the internal wirering. – see modified diagram.
The capacitors must be able to handle high voltages – I’m using 500V ceramic tubular types and have no problems at the 100W level.
This modification improves the return loss at 30 MHz from -12dB to -30dB and at the same time reduces through loss (attenuation) from 0.3dB to only 0.1dB.
By OZ2OE originally at hjem.get2net.dk/ole_nykjaer/oz2oe
Six Meter Wavelength Band Antennas
The advent of new, affordable MF/HF/VHF radios in the last few months from virtually all the major manufacturers, has spurred a migration by more and more Hams to the Six Meter band. I’m often asked, “What antennas are best for Six Meters?”. Before answering a question like this, I must first ask the Ham what he or she knows about the band, and in what sort of activity they want to engage. Often times I’ll get a response such as, “Well, I just want to get on six!”.
Next I’ll want to find out what sort of a Six Meter station the person might already have. As often as not, my preconceived notion of the Ham owning an MF/HF/VHF transceiver is dispelled. They may tell me that they have a 50 Watt FM transceiver, or maybe a Six Meter hand-held radio. They usually follow this response by indicating that they are really anxious to work some of that Six Meter DX they have been hearing about! My task has at this point fallen to explain the entirety of activity on the band, and what is needed for each of the various modes of communication available on the band.
You see, the Six Meter band works almost as if it were two distinctly different bands rolled into one. Down at the low end of the band most operators are interested in working distant DX states and countries on Single Sideband (SSB) or Morse code iCW. At the upper end of the band the predominant mode is Frequency Modulation (FM).
Most of the people that you’ll find at the top of this band have used it for years and years as a sort of quiet intercom channel to talk with college buddies or other friends. In this upper portion of the band the activity is similar to the two meter band, with perhaps a better sense of manners and operating skill. The lower end of the band is where the “Big Fun” is! In this lower spectrum, distant (DX) signals are often found, resulting from a myriad of propagation sources. This is why Six Meters is known as the “Magic Band”!
Why 6 Meter Hams Design The Best Antennas
At this particular juncture in time we are quickly approaching what seasoned Six Meter Hams call “F season”. This is because in the next several months we will see a transition from relatively low “Solar Indices” numbers hovering at about 100, to an increase that we all hope will exceed the 168 solar indices peak of 1958. During this 1958 peak, many Hams worked all states within our country, and several zealous individuals worked all continents.
Other signal propagation modes are also common on this band. Even at times when signal propagation is “shut down” on the HF bands due to solar storms called “proton events”, Six Meters will often yield Auroral skip. This can be really fun to operate, and is distinguished by the eerie and gravelly sounding phase distortion that occurs.
Another mode of propagation I have enjoyed over the years is “Meteor Scatter”. The best meteor skip I have successfully worked is during the Geminids and Ursids showers in December. I have also though had good luck on occasion with the many showers that occur in June and July. Here is a listing of these, and the approximate dates of their peak:
Scorpids June 2 through 17 Perseids June 4 through 6 Arietids June 8
Pons Winnecke June 27 though 30 Taurids June 30 through July 2 Cygnids July 14
Capricornids July 18 through 30 Perseids July 25 through August 4
Meteor skip allows about ten to twenty minute conversations or QSOs as the earth rotates below the ionized meteor trail. You might think of this sort of propagation as the “billiards of Ham Radio”. The way this works is that signals from my station in Anaheim go up and bounce off the meteor trail and come down in Texas. As the earth rotates, twenty minutes later I can talk to a station or stations in New Mexico. The arc of this propagation will ultimately yield contacts for me in Utah, Idaho, Washington and Canada before the signal starts coming down in the Bering Sea. I have seldom worked Alaskan stations via this mode of propagation but, I hope to as more Hams acquire Six Meter equipment! It would be nice to follow this propagation all the way to Russia. I have never worked any Russian stations however, probably due to the economic and political situation of the then Soviet Union.
A final form of skip that is often mis-judged by Hams who exploit it even on 10 or 12 Meters is Sporadic E-Layer skip. The ionospheric E layer resides above the earth at approximately 80 miles up. The F1 and F2 Layers by contrast are about 60 to 200 and some miles higher. This is why F layer skip typically yields further contacts because of the consequential lower angle of propagation. E skip on Six Meters is a very common occurrence during the months of April through July. It is believed that stimulation of the E layer occurs at this time because of high thunder head conditions during spring storms. I have tracked and confirmed this sort of activity in the past by correlating it to weather warnings given to airline pilots. Generally speaking, the Six Meter activity will come about a day or two after the highest thunder storm activity. This sort of skip yields single, double and even triple hop skip. During one E season when two “E-clouds” were simultaneously over the midwest and southwest on the weekend of the June VHF contest, stations all over the country were talking to one another on Six Meters. It was an unusual sort of gentlemanly bedlam that covered better than 300 KHz. at the lower end of the band!
Back to Antennas
If you’re interested in Upper Sideband (USB) you will run into folks who will tell you that you should use a horizontally polarized antenna, probably a Yagi Uda beam. If you want to work FM, everyone will tell you to use a vertically polarized antenna such as a Ground Plane or a “J”, since that’s what the mobile stations and everyone else is running. Well, here’s the low down scoop so you can have your cake and eat it too!
Use a vertical omni-directional antenna for both modes, actually all modes, and you will have the best of all possible worlds! I say this based on my own experience, as well as others who have worked a great deal of DX with vertically polarized antennas. For about 31 years now I have used vertical omnis on this band to very good success. I’ve worked all 50 states, and four countries, most times running not more than about 100 watts of power.
I’m not knocking beam antennas such as Yagis or Cubical Quads, I have used them too! What I’m really saying though is that I have learned to put them up vertically polarized as opposed to using them in horizontal polarization. One station I can think of has worked all states more than twice over, as well as working all continents using a pair of vertical five element Yagi beams.
The reasoning behind this becomes more clear if you consider that propagation on this band is more often similar to that of an High Frequency (HF) band, rather than a VHF band. On bands like 2 Meters or 222 MHz., when you operate Single Sideband (SSB) you would probably be foolish not to use a horizontal antenna. In my experience on the Six Meter band, signal propagation comes in most times at an angle that is closer to the vertical plane, than it is to horizontal.
About the only time using a vertical antenna would be a disadvantage would be trying to talk to a horizontally polarized station within your “direct wave” range. This would be a station within about 50 miles of you. In this circumstance about an additional 20 Decibels of attenuation would be imposed between the cross polarized stations. In reality though all Six Meter stations should have an omni-directional vertical antenna. With such an antenna you will be aware of the prevailing activity on the band, even if you then switch to some other antenna to optimize that activity.
So what sort of vertical omnis are desirable? Ground Planes work well, either the 5/8 wavelength variety or even simple 1/4 wavelength versions. These can often be fabricated from easily modified Citizens Band antennas. The venerable “J” antenna is though, probably both the simplest to build, and the best overall performer. One major reason the voltage fed “J” is nice is that it can be constructed to provide enough bandwidth to utilize almost all of the band. This allows you to have one antenna that can be used for FM, AM, SSB, or CW. So, what must be done to provide this wide bandwidth J antenna?
Bandwidth in an antenna is a function of the antenna’s circuit “Q”, or circuit “quality factor”. If the antenna provides the lowest possible reactance, the Q will be improved, and consequently so will bandwidth. To provide the lowest possible reactance, or Alternating Current (AC) resistance, we could either use large diameter conductors, or maybe plate the antenna with some nice low resistance conductive material like Silver. I think using fat large diameter tubing is probably the better and more economical approach!
Usually 3/4 inch diameter tubing is used for Six Meter “J” antennas. If this seems like a desirable mechanical configuration to you, here are the dimensions for such an antenna fabricated from copper tubing. Actually it uses 1/2 diameter tubing also but, hang in here with me, we’ll make use of this smaller diameter tubing in a later modification for higher frequency bands!
First, let me explain how we do these measurements! Start all your measurements from the top edge of the bottom of the antenna. This means the top edge at the bottom of the “Q-Line” or Linear Impedance matching transformer that is formed by the two parallel quarter wavelength tubes. So let’s get started by listing the parts you will need.
The “J” Shopping List
* One 10 foot length of 1/2 inch copper tubing
* Two 10 foot lengths of 3/4 inch copper tubing
* One 3/4 inch “T” fitting
* One 3/4 inch to 1/2 inch reducer
* One 3/4 inch elbow fitting
* Two 3 inch by 2 inch by 1/2 inch thick pieces of Plexiglas flat stock
* One coaxial SO-239 chassis mount connector, or maybe a chassis mount “N” connector
* 6 inches of #12 American Wire Gauge (AWG) THHN solid copper wire
* One ring type crimp-on terminal to attach to the connector’s flange
You will also need 4 appropriately sized screws, nuts and lockwashers for the connector and, also eight (8) 3/16 inch machine screws and lock nuts for mounting the Plexiglas plates.
[6mtrJ.gif] Putting This Puppy Together
Remember to clean and polish all these copper pieces, as well as the tip ends of the tubing that will fit onto them before soldering! Use non-acid solder!
Use a tubing cutter so as to make nice smooth even cuts. Cut one length of 3/4 inch tubing such that it is 59 inches long when seated with the elbow fitting and mated to the shorter leg of the “T” fitting. You will need a short piece of tubing to accomplish this so that proper spacing can later be accomplished. Next cut the second piece of 3/4 inch diameter tubing such that when it is fitted within the top port of the “T” fitting, it is parallel to the 59 inch piece, and its total length is 109 inches. When this has been done, adjust the center to center spacing between the two parallel tubes to 2.750 inches. Make sure they are still exactly parallel, and solder these pieces together.
Place the reducer on top of the longer piece, and cut a 1/2 inch diameter piece to exactly 50.25 inches. Clean up this last piece and solder it in place. Let the antenna cool off while you fabricate the Plexiglas bracing plate, and “feed-point” connector assembly.
Drill a 5/8 inch hole in the exact center of one of the Plexiglas plates. Place the coaxial connector you are using in this hole, and mark the plate for each of the small mounting screws. Drill these four holes, and also four holes near the corners of the plate where it will be mounted to the Q-line.
Snip the 6 inch wire in half. From one end of each wire, strip about a 1/2 inch of insulation. Strip about 3 inches from each of the other two ends. One piece of wire will be soldered to the center pin of the connector at the 1/2 inch stripped portion. The other piece of wire will have a ring connector installed at this point. The ring connector will later attach to one of the flange screws for the connector.
Place this finished Plexiglas connector assembly such that it is straddling the two parallel tubing pieces. Using a pencil, mark positions beneath this plate to drill holes for soldering the 3 inch stripped portions of wire. The center pin wire will connect to the longest piece of tubing, and the shank side of the connector will be soldered to the 59 inch Q-line. These connections will be made exactly 5.300 inches above the top edge of the lower end of the Q-line. This is a very critical dimension! It affects the feed point impedance, and the resulting antenna Standing Wave Ratio (SWR). Bolt this plate assembly in place with four 3/16 screws and lock nuts. Place the second similar plate on the Q-line about six inches below the top end of the Q-line, and bolt it in place.
When the antenna is mounted high and in the clear of all nearby objects, it should provide a good low VSWR over most of the lower two and one half to three megacycles of the band. It is desirable to mount this antenna at least 30 feet in the air, and higher if possible. I would also recommend the use of high quality 50 Ohm coaxial cable such as Belden RG- 213/U. To mount the antenna, you can use a threaded plumbing fitting, or make a mounting bracket fabricated from 1/4 inch thick aluminum plate stock and TV antenna type “U-bolts”.
Later modifications to this antenna could also allow it to be used on the 2 Meter band, as well as the 135, and 70 Centimeter bands. This can be done by exploiting the “odd order” harmonics of the Six Meter band, or better, by adding Q-lines for these other bands.
Other Antennas for 6 Meters
While we are thinking about the Six Meter band, let’s consider some antennas that will work on this band that are not often appreciated. The manufacturer “Hustler” makes such an antenna, and so does Larson.
The Hustler “top loaded” HF mobile antennas will work on 6 Meters. This is because the supporting mast is 54 inches long, which is 1/4 wavelength on the Six Meter band. You can use this antenna on Six, even while one or more “resonators” are attached above the mast for various HF bands. This is because the inductively loaded resonators become “RF Chokes” at 50 MHz.
This way if you have resonators on the antenna for lets say the 40 Meter, 20 Meter, and 10 Meter bands, you have a 4 band antenna as it will also work on Six! It will even work on the 2 Meter band. This is because 54 inches is pretty close to 3/4 of one wavelength on 2 Meters, and this “odd order” harmonic relation will allow the antenna to be close to a 50 Ohm impedance match as well. The radiation pattern on 2 Meters won’t be the greatest but, you will probably find that as a mobile antenna on your car, this system works well for the entire HF through 2 Meter spectrum.
Another 2 Meter antenna that will also work on 6 is the Larson 5/8 wave mobile antenna, or the Hustler 2 Meter “Buckbuster” 5/8 wave 2 Meter antenna. Electrically this 47 inch antenna looks like a “base loaded” 1/4 wavelength antenna on 6 Meters, and up on the roof of your car, it will be quite efficient!
A Super Six Meter Setup!
Finally, let me suggest an approach that should yield both good electrical performance, and provide the signal gain of a beam antenna. This system should prove to be a good way to go for the Ham who has not yet installed an antenna tower. It also has the advantage of allowing the Ham to electrically switch the antenna’s position randomly, and in effect, scan for signals. This approach is to take four vertical omni-directional antennas and “point them” by means of a coaxial phasing arrangement.
I am quite enthusiastic about this antenna because it might allow, in a later configuration, an antenna that can be “automatically operated” by a computer. If another plan of mine comes to fruition, 6 Meter Sporadic E layer, or Meteor Scatter could be “worked” automatically on 6 Meter Packet radio. The national 6 Meter Band Plan uses 50.620 MHz. as the “Experimental Packet” frequency. This allows for any legal baud rate (which would practically mean any baud rate from 300 to 9600 baud) and encourages experimentation. No one that I am aware of up to this point in time has utilized packet for working this sort of DX ! It would be a beautifully workable scheme, and allows for some good and timely scientific activity. We as a “hobby” avocation need to use computers for more than (stupidly 1200 baud) slow packet messaging!
The vertical omni I would prefer is this same design “J” antenna. This particular sort of antenna provides excellent control of reactive matching impedances via its quarter wavelength linear impedance matching transformer. It also by happenstance gives us a physical advantage, as we can get what might prove to be a cumbersome configuration of antennas a bit higher in the air. My design thoughts for this antenna system should allow for putting the “high current point” of the antenna at about 25 feet, when it sits atop the roof of a house that is ten feet tall. This puts the radiating portion of the antenna about 1.3 wavelengths above ground. This then can be done with what would otherwise become the wastage of the copper tubing not used for the one antenna itself.
The configuration of these antennas is commonly known as a “4 Square” arrangement. This configuration places the four antennas at points of a square that are one quarter wavelength per side. The mathematical dimension calculation for this physical mounting works out this way. :
300/50 MHz. = 5.88 Meters
5.88 X 39.37 = 231.59 inches
231.59 Meters/4 = 57.89 inches
The above formula embodies these perameters. Three hundred (300) is the velocity or speed of the signal transmission. Actually this is 300,000,000 meters per second but, since we are dealing in Mega cycles, we can truncate six zeros. At this point in the formula we have the actual metric wavelength of signal propagation at 51 MHz. 51 MHz. is chosen to put the “design frequency” in the middle of the antenna’s practical bandwidth.
If we then multiply this by the number of inches contained in one meter (39.37) we have this same wavelength converted to inches. Dividing this 231.6 inches by four gives us 57.89 inches. Placing the antennas in a square that is 58 inches per side is quite close enough and accurate for practical purposes. Take note that the length for phasing “Delay Lines” for electrically feeding these antennas will be further modified to allow for the “Velocity Factor” of the coax cable used!
The above described antenna system should in theory result in 5.2 decibels of directional signal gain. In a future article I will explain the mechanical mounting components as well as the phasing lines and switch box control. A future iteration of this design may allow for computer control. This would actually be quite easy to do, and as soon as I can justify building the system myself, or finding someone who finds this idea as attractive as I do, we might collaborate together. It would be great to find someone in the Texas up through Washington state “one hop skip zone” that is a single skip zone away from me. This would allow for initial testing on a more or less regular basis! Send me some e-mail if your interested!
Article by Wa6BFH originally at /www.geocities.com/SiliconValley/2775/6mjant01.html
Stacked Yagi Antennas
This article was obtained from VE3GK experiences, constructing and designing full size, single band stacked yagi antenna arrays, special rotating, electric powered, telescoping towers and rotators. All the test results are from first hand experiments. VE3GK kept a record of these experiments and construction details and offer them for your interest.
HISTORY
I started out in amateur radio with wire antennas. Directional antennas were next and I erected a commercial tri-band antenna, tower and rotator. Another amateur, nearby, used a wide spaced mono-band 20-meter beam, which blew me away every time. From this experience I felt that my set up left a lot to be desired.
I started with a 5-element 20-meter mono-band yagi on a 48-ft boom. As the years passed several different home made full size long boom multi-element yagis were mounted singly and in the stacked array configuration on modified lattice towers. These towers were modified to rotate to accommodate the stacked array set up.
Antennas were eventually mounted on two home designed and home made continuous heavy duty telescoping rotating tubular steel towers. Stacking separation distances and overall height above ground experiments were conducted on the large tower on a small mountain 65 miles south of Ottawa at our summerhouse. In the winter time, in Ottawa, I experimented with a smaller, 75 ft rotating telescoping home made tower. The tower is designed for continuous operation. I try to lower the thing out of sight in the trees, in its parking position, every time I leave the shack for over 30 minutes or so. Out of sight, out of mind, for my neighbors. (My stealth equation HI) This tower also tilts over electrically with a permanent 5 in diameter, 12 ft high gin pole mounted in the cement base.
This in a neat arrangement for ease of antenna installation and adjustment. With the exception of the commercial tri-bander all of the hardware presented in this paper is home constructed and home designed.
My present radiating system is a 20- meter, four over four stacked array with yagis on 40-foot [12m] booms at the summer place. All of my mono-band yagis use odd spacing with a close coupled first director and placed 0.1- wave length in front of the driven element. The top beam is usually at 90-feet [27m] and the bottom one at 42-feet [12.6m] when in the stacked arrangement.
The Gk Hb 4×4 20 Meter Stacked Array On A Hb Skyneedle Tubular Steel Tower.
Two 4 element 40 foot boom yagis fed in phase. When up, one at 95 feet and the other at 38 feet. When nested, one at 28 feet and the other at25 feet above ground. Nesting happens automatically in wind gusts above 60 kph, when I leave the property and at the end of operating hours or evening shut down. The time travel is 7 minutes 40 seconds up or down. There is a manual crash descent, (Letting the tower free wheel down), of 30 seconds in case of a sudden storm. The estimated tower weight is 2.5 tons, 2 tons are active when the tower is under power. This weight is supported by the lift cables (16 tons capacity) at all times. The tower is freestanding, telescopic, rotating, remote control, double safety devices on all tower sections and lift cables. Automatic end stops on the tower extension and nesting positions. Also safety devices on full cw and ccw rotation parameters. The hoist and rotator parameters are monitored on close circuit tv using two tv cameras. Audio feed-back information is feed back with a baby monitor.
The following conclusions are based on my own full size live tests, and are to be weighed accordingly.
I want to thank those people who helped me with all the antenna tests. I especially want to thank those who were patient enough not to shoot me off the top of the towers during the tests.
NOTE:
In the commercial antenna market their seams to be an emphasis on working as many bands as possible on one boom with mediocre results on any one band. Don’t believe the claims that multi-band beam antennas exist that can compete with antennas designed for one band. Log periodic beam antennas are not high gain antennas, they are wide band coverage devices that have gain compared to that of a 3 element beam antenna , designed for one frequency.
In Ottawa I use a commercial 5-element tri-band yagi on the telescoping, rotating, 75-ft tower. This fall and Winter it is my intention to stack another identical tri-band yagi on the tower at 25 ft. These experiments are possible because I can adjust the stacking separation distance for 10 and 15 meters. I will not be able to stack on 20 because the top beam is not high enough. (The tower is higher but not capable of supporting the weight of the heavy tri-bander on the top section
MEASURING GAIN WITH REFERENCE TO A DIPOLE:
Measuring gain with absolute certainty is very difficult because of all the variables. However, as far as I can determine the gain of the present 4X4 array is about 11 DBD. [db reference to a Dipole]. The single 40 ft long 4 element beam is responsibly for about 8-DBD and the stacks at 3/4 wave separation with the top one at 90-ft add another 3-DBD to the results for a total of 11-DBD.
Antenna gain is measured with reference to power gain. For example; when the power of an amplifier is doubled from 100 watts to 200 watts, the resulting gain would be 3 DBP; the “P” stands for the previous condition or situation. This 3 DB factor comes from the formula that states that power and therefore, antenna gain is equal to 10 times the log, to the base 10, of the new situation divided by the old situation. Here the new power divided by the old power equals 2, the log of 2 equals 0.3 and 10 times 0.3 equals 3, 3DBP gain.
A practical antenna gain measurement could be done as follows: Mount a 20m-reference dipole and oriented it at the proper height, far enough away to de-couple any interaction with the test array. Apply 100 watts to a dipole as indicated on a good wattmeter such as the BIRD 43. Have another amateur, at least one skip distance away, and note his “S” meter reading. Then apply power to the test array and reduce the power and one should get the same “S” meter reading with lower power. This operation has to be done very quickly to out-run any QSB on the band. In my case with the present 4×4 array I am able to get the same “S” meter reading with only eight watts. Divide this 8-watt power level into the 100-watt reference and the results will be approximately 12. The log of 12 is about 1.1 and 10 times 1.1 equals 11, 11DB. Arriving at an honest DBD gain factor is very simple.
THE GAIN STORY:
1. The mathematical Isotropic RF point source. zero gain (RF point source inside a sphere>>>> NO RF BURNS).
2. The dipole, approx. gain over the isotropic point 2.15-DBI
(Because of its butterfly pattern)
3. 2-el 80 meter rotating diamond quad, 40-ft [12m] boom diamond tip at 117-ft. [35m](North American QRM down 7-“S” units on the side when working Europe)(GK 91) gain 5-DBD
NOTE: from this point on, all reference to gain is related to the dipole. [DBD].
20 METER ANTENNAS:
4. 2-el quad 12-ft [3.6m] boom. (GK 67) approx. gain 5-DBD
5. 3-element 19-ft [5.7m] boom. (GK. 69) approx. gain 5-DBD
6. 4-element 26-ft [7.8m] boom. (204BA) approx. gain 7-DBD
7. 4-element 40-ft [12m] booms. (GK. 91) approx. gain 8-DBD
8. 5-element 50-ft [15m] booms. (GK. 85) approx. gain 9-DBD
Probably the limit for practical HF gain return for effort
and money with single yagis)
9. 7-element 65-ft [19.5m] boom. (GK. 74) approx. gain 9-DBD
(I KNOW, I KNOW, BOOM TOO SHORT)
10. 3 X 3 stacks, 25-ft [7,5m] (GK. 75) approx. gain 9-DBD
(Each of the following stacks had a minimum of 0.75 stacking separation)
{booms}
11. 4 X 4 stacks, 30-ft [9m] (GK. 76) approx. gain 10-DBD
12. 4 X 4 stacks, 42-ft [12.6m](GK. 77) approx. gain 11-DBD
PRESENT ARRAY:
13. 4 X 4 stacks, 40-ft [12m] (GK. 97) approx. gain 11-DBD
14. 5 X 5 stacks, 42-ft [12.6m](GK. 80) approx. gain 10.5-DBD [BOOMS TOO SHORT]
15. 5 X 5 X 5, stacks 50-ft [15m] ….. approx. gain 13-DBD
(15. probably the limit for effort and gain return for HF
single stacks) listen to Ivor, GI0AIJ.
16. 4 X 4 by 4 X 4 collinear stacks, approx. gain 14-DBD
17. 5 X 5 by 5 X 5 collinear stacks, approx. gain 15-DBD
(17. probably the limit for effort and gain return for HF collinear stacks)
Simon, OH8OS, in Finland, had a 6X6 by 6X6 by 6X6, 60-ft booms
horizontal separation of 60-ft, Top antenna over 200-ft
above ground. A total of 36-el. Approx. Gain ??-DBD
WOW! Is this a 20-meter monster antenna array or what?
Note: A dipole would have to be driven with a bunch of kilowatts of power to equal the output from the OH8OS array with bare-foot power. All that power into a dipole with no receiver gain. WOW! For instance, you would have to drive a dipole with about 700-watts to equal the output power of a 204-BA, Hygain 4-element beam with only 100 watts drive power. Can you imagine the legal power limit to the array OH6OS used, don’t fry, oh sorry fly, in front of the sucker if Simon were to sneezed into the microphone. HI.
GAIN
GAIN REALLY HARD TO COME BY:
LONG BOOM SINGLE BAND YAGIS:
When a person asks “what’s that big aerial thing doing up there..EH ?” I always say. “If you think the aerial is big, you should see the size of the TV set.”
“That’s not QSB man. It’s the wind blowing my antenna around.” My 7-element on a 65-ft [19.5m] boom had a very narrow beam pattern. It was also big enough because it blew up and over the top of the tower in a January ice-wind storm in 1975, more later. It was my first “JC” antenna. People would drive by and fall off the road. Other amateurs would drive by with their spouses and suggest a tri-bander! If you hear a big signal break the pile up, listen to the description of that station. I can assure you, a lot of time, money and effort has gone into the signal. Some people rationalize the strength of a very strong signal by assuming high-power. I’m accused of running over power. I sometimes say, “I’m running illegal antennas”.
Note: the reflector for this ve3gk 6 element 20-m yagi is sitting on the ground at the base of the tower
This antenna was used as a reference source for my 5X5 and 4X4 stacked arrays for a period of time. My QTH was about 6 KM away.
<<
Ve3gk, doing his “walk the boom trick” in my younger stupid days! Near home brew 60-ft 20-m yagi at 90-ft
VE3GK antennas…..
Over the years, there has been some big, long boom yagis up. The photo to the right shows W4GNR sitting at the top of his 140 ft high tower on the 120 ft long boom 20 meter yagi up at 140 ft. I remember a 20-meter yagi in the early 1960`s in the mid west USA, a real monster. The thing had 12 elements on a 150-foot [45m] boom up 150-feet [45m]. A real cannon, it surely would have been a sight to behold. With what we know now this antenna would have worked more efficiently with fewer elements. It was also up too high for in close DX such as Europe because of its very low launch angle.
Remember; gain from a long boom single band Yagi comes from the focusing of the frontal lobe by the extra director’s way out on the boom. From my experience, when you have a long boom the forward gain and the front to back ratio is one and the same because of the refined frontal pattern.
The take off angle to the horizon is mostly related to the antenna height above true flat ground for single yagis. If one gets involved with a stacked system its a different ball game. A tacked system modifies the take off angle with startling results. From my experience, it eliminates one skip distance to Europe. My advice is that you do the best you can with what you have and go for it. As a rule, single antennas will work really well at one wavelength above ground. The antenna performance will really come alive at 1.5 wave-lengths above ground (99-ft for 20 meters). You will be amazed with your new signal. If the antenna is placed much higher the in-close path to Europe from North America will suffer. Asia and the Indian Ocean area will be better so you have to make a choice. The next paragraph could solve this Delrina.
THE TELESCOPING TOWER:
With a remote controlled, telescopic tower, one can experiment with the launch angles for changing DX openings. As far as I can tell the towers that I have built are the only ones that have the ability to fully rotate and are free standing. Also, most telescoping towers are not designed for continuous height adjustments so it’s not feasible to run the experiments. The towers that I have are specially designed to perform these tasks. The large 118-ft tower at my DX location at the summerhouse is designed to modify the take off angle for the ideal skip condition. I don’t know of any company offering this tower commercially.
The 100 ft tower on it’s way
On a lighter note, with a telescoping tower you can let the tower grow on the neighbor’s say a foot every day HI. Maybe make the hoist system ultra fast about 1-ms for full up or full down in the trees. You could put a neighbor sensor on the thing and when they look out the window down it comes. “What tower, what antenna? EH” All kidding aside, its interesting to be able to adjust the take off angle for different areas and times of the day.
My second 80-ft (24m)-telescoping tower in Ottawa tilts over. This is fantastic for the initial erection and flexibility for future modifications. Most importantly, is that initially you don’t have to have a high profile crane come in. That’s “high profile City.” Neighbor: “You know when that BIG CRANE came over to your yard and you had the big erection, well ever since that thing went up my washing machine has been over sudsing!”
BAND WIDTHS AT THE HALF POWER
From my experiments the yagis that I constructed had wide low reflected-power bandwidths that usually cover the entire band with less than 2 percent reflected power. I am fully aware of the theory that a narrow bandwidth results in a larger gain factor. However, I seam to have more than enough gain from my practical experiments and the ability to roam the entire band with low vswr in very appealing to me. VSWR curves above 1.5 to 1 on my long yagis were usually occurred outside the band on 20-meters. The half power points were awesome at plus or minus < 30 degrees. Half power beam density points are those points that are out to the sides of the beam pattern and are 3-DB down with reference to the maximum density of the middle of the beam pattern.
There are certain construction techniques used when building short yagis that seam to indicate that one can tune either for maximum front to back or maximum forward gain. Usually, the frontal lobe will be skewed and the forward gain suffers a little. I should not comment further because I have real problems relating to antenna things that I have not experienced first hand. I have always worked with long boom yagis and in this situation one works both on the front to back and with the focussing of the energy in the frontal lobe. Elements, far out on the boom, focus the energy. The gain comes from the missing density from the mods in the rear lobe by the reflector and the side’s lobes by the directors and more importantly the long boom. From these experiences, I find it very difficult to separate the front to back with the forward gain. Again, I feel the forward gain of the array is directly related to the re-arranged flux density both on the back and the sides.
THE NEIGHBOR ANXIETY INDEX:
Large antenna arrays are prone to all sorts of problems, not the least, the anxiety level of all the neighbors. My large telescoping tower with the stacks is mounted in the trees on the edge of a large lake in eastern Ontario. This QTH is the highest area in eastern Ontario. About a mile of water separates my QTH from a large campsite across the bay. I ventured over their one day and was asked, “what do you think that strange structure is across the bay?”… “The thing is there sometimes, and sometimes it’s not. WOW! .. Very strange.” I said, “I thought it was some sort of secret government installation, an area to be avoided at all costs.” When people bring your antenna system up in conversation, just say “thank you, thank you,” and tell them that the thing will protect them from lightening storms, “just my little contribution to the well being of the neighborhood.”
Watch for the gun barrels out the windows. Maybe you should only climb the tower at night in the city.
THE PUBLIC RELATIONS CAPER:
On a more practical note, last year I used my snow blower to clear several neighbors’ lane ways while they were at work. HI
Start with the popular, Hy-Gain, 204BA, a 4-element Yagi on a 26-ft boom and double the length to 52-ft, [15.6m]. You should only add one extra director for a total of 5-elements in this project. (Obviously, I think the present design of the 204BA is over-populated with elements.) However I still admire the design of this antenna because it’s a strong competitor on band. I know this sounds odd but for what it’s worth I think the 204BA is actually a 3-element beam with an extra director. The first director is a foot [0.3m] longer than the other directors and is always placed 0.1-wavelength (7-ft) [2.1m], in front of the driven element on 20-m. Some amateurs have called it the phantom element. I use this odd, close-coupled, over size, director design on all my yagis and feel that the results are really worthwhile.
The spacing on the 205GK, 5-element were, starting from reflector end: 12-ft [3.6m], 7-ft [2.1m], 15-ft [4.5m], and 18-ft [5.4m]. The element lengths stay the same as the 204BA and the last director is 2 inches [5cm] shorter than the one before it. I also substituted an OMEGA match for the original 204BA-matching network. Complete details are in another chapter. Wait until you try this new super 205GK modification to make the 204BA into a 5-element on a 52-ft [15.6m] boom. This antenna will astound you. You can throw out the theoretical 2-DBP-gain figure. It seemed most of the time to be around two “S” units. I remember a five element made by a well-known beam manufacturer on a 46-ft boom that outperformed their 6-element on the same boom. However, the company made the 6-element available for those who wished to say they were running six elements. Some beams have several driven elements to cover the bandwidth. My long yagis designs cover the whole band with lots to spare, more later. I understand that the antennas should work better at some point in the band, but I don’t see any change in performance over the entire band. Five element yagis were a passion of mine in the 70`s and 80`s and I built several of them. The largest one was on a 53-ft (17.6m) boom. I also built a 7-element on the 63-ft (21m) boom, and fun learning project. I know, I know, 7-elements on this length of boom was too crowded, the boom should have been about 100-feet [30m] long, but you learn as you go. I describe these home brew beams in other chapters.
THE THREE ELEMENT YAGI:
I have to say that I have never had any real success with a 3-element yagis design. Oh, I got them to work but they didn’t have that magic touch in a crowd, even when I stacked them. I think all mono-band beams need the magic short-coupled first director, so there has to be a minimum of 4-elements. So I guess the three-element beam for 20 meters is not in the big game. Remember if you don’t agree with my observations turn the dial, HI. From my point of view, the 4-element single band is the most popular competitive beam in use today on 20-meters.
DO NOT READ THIS PARAGRAPH:
You know it appears to me a lot of people are just relying on other so-called experts to do they’re experimenting for them. Some of the gain figures are really inflated as far as my experiments dictate. I hear that there is a magic 2-element on 20 meters on an 18-ft boom, crowded with other bands, that has a 10-DBD + gain figure. Must be some magic here. Think about it, would operating 100 watts to the thing be the same as running 1100 watts to a dipole in the same spot? NOT!!!!!!!
“Let me run your design by my computer program and see if it’s a good design”. This is right after I have broken a force 10 or 12 pile-up with 200 watts bare foot on the first call into Asia. “No…, you run your program by my design and see if it measures up.
Because of gusty winds and heavy ice in some areas, the life expectancy of large beams is short. The big guys require special towers and extra special rotating systems. I used to rotate the big beams with long drive tubes with the rotator mounted at the base of the tower at ground level. Steel wires ran down the side of the tower to show the beam heading independent of the backlash of the long tube. The main reason for the tube was to eliminate the need for the tower to handle the severe torque power from the long booms in heavy winds. Is it ever neat to be able to get at the rotator at ground level, especially in the dead of winter? As an added torque absorber, I over-lapped two diameters of the torque tube just above the rotator. Then I welded a large automobile front-end suspension coil spring onto each tube so that the spring was in series with the drive system. This “spring” idea came from Gib, VE3BGX in Ottawa.
Special rotators had to be designed for the new rotating towers. One design used four VEE belts in parallel. (I think this was the best design). However, the belts had a short life span because of the proximity to oil and grease. Because the tower had to be lifted out by crane in order to change the belts, a second method was designed using small diameter steel cable. The cable design was not unlike the winch method mounted on its side. This is the method I use at present on the large tower. The smaller 1.5 ton tower uses a new design using a linear drive consisting of a 30 inch, [75CM], 3/4, [2-CM] inch diameter, 10 turns per inch threaded rod driven by a one third horse power electric motor. This new design does not require an expensive gearbox reduction drive assembly. Also this rotator could be located at ground level and drive cables could run several hundred feet to the top of the tower. This cable rotating method also relieves the tower of any responsibility for torque restraint. A heavy-duty relief spring is installed in series with the drive cable to relieve any bumps in torque due to gusting winds. The rotator has more than enough power to rotate the largest 80-M beam -tower at a fraction of the cost. There are no expensive gears to strip and the unit is self-braking. A triangle tower could be rotated this way quite easily because the wire winch drive can’t tell the difference between rotating a circle or a triangle. One would have to re-calibrate the beam indicator because of the difference in the diameter from the point of the triangle to the side of the triangle. The other option would have steel drum welded to the tower so that the radius of the tower remain constant.
THE NEW ERA OF THE SHORT BOOM YAGI ANTENNA.. MAGIC GAIN ANTENNAS?
Don’t let anybody claim they have a magic antenna on a shortened boom, with less elements, that works as good as or better than a longer one because they are just fooling themselves and trying to fool you. Logic dictates that a boom with other elements for other bands on it will not work as well as a boom dedicated to one band.
THE BRONTOSAURUS GUN:
REMEMBER…..Combine the gain from several long boom yagis in the stacked array and you have a real brontosaurus gun.
My brontosaurs gun the 7 element on the 68-ft boom at 90 ft