Here is a copy of an article on a full wave horizontal loop antenna, feeded with a balanced line.
This article was originally published at k4qky web site, but seems has been lost. I keep here a copy for public reference.
Moonraker supply a whole range of wire trap dipoles covering from 2 to 5 HF bands (MTD1; MTD2; MTD3; MTD4; MTD5; MTD6). Diamond also produce trapped wire antennas, the W-721, W-728 and W735. Comet and Diamond each produce similar interesting 5 band wire dipoles that utilize both traps and a fan arrangement – the Diamond W8010 and the Comet CWA-1000. If space really is limited then look out for KZJ Communications (dongo1950 on ebay) – he produces ‘Limited Space Inductive Dipoles’. These are inductively loaded and shortened dipoles so they will have reduced efficiency, of course, but are very nicely made, so might be very useful in a tight spot.
To obtain good efficiency and achieve a low angle of radiation, desirable for longer distance DX, a horizontal dipole needs to be installed at a good height – over 20 feet would be desirable and it is quite common to install horizontal dipoles at around 30 to 40 feet above ground level. This might be a problem at some QTH’s, it certainly is at mine!
Allan Copland, GM1SXX comments: “The dipole will operate well on the band it has been sized for , if placed at a suitable height, but will also operate as a’ three-half-wave’ aerial at three times the frequency and so on, so it’s not strictly a single band aerial. An 80M dipole (132 feet typical) will work nicely on 30 metres (three half waves) but not on 40m (two half waves)… because on 40M the feed-point is at a voltage node and not at a current node, for easy feeding. Most aerials are current fed.
The radiation pattern changes when a dipole is not used on its design frequency. The pattern will break up into multiple ‘petals’. This can be either a disadvantage or an advantage depending on what you expect from it. Since most of us use co-ax, an UN-BAL should really be used to connect the unbalanced feeder to the balanced aerial, but how many people actually bother? Not many I suspect. It’s possible of course to use a balanced feed-line system instead with a dipole and just have a delta match (no centre insulator… none needed). There are many choices and permutations, but in general, dipoles are centre fed at a point of current maximum (and minimum voltage).
A normal dipole is current fed but of course can be voltage fed instead. This is what’s done in the EFHWA or Fuchs aerial where a resonant half wave wire is fed at one end (max voltage / min current) from an L/C tank, against a very short counterpoise wire.
Original article is :W3DZZ Dipole Aerial design by the Maidstone Amateur Radio Society
Here we are with the new toy recently purchased via Amazon witn case, wifi dongle, and cables, as my yearly christmas present for myself.
The idea is to setup a WSPR beacon for 40 meters. This will be my first project to complete.
I know this toy is easy to be used for many other usages, but I’ve decided to focus my attention to this first goal.
I’m collecting now documentation to better understand how to setup the Raspberry and the WSPR software.
https://github.com/JamesP6000/WsprryPi – this souds like to be the preferred client to be installed.
I’m accepting suggestions and other ideas or examples of raspberry usage within the ham radio world.
Since I had the Budwig HQ-1 with the SO-239 moulded in the unit, I put PL-259s on each end of the matching coax and then used a barrow splicer to put the regular 52ohm coax feedline to the antenna.. A little weather proofing and this setup has worked well for many years.
My mounting point was only about 45′ above ground, which is insulated from the tower by a 3′ fiberglass pole. The legs of the antenna were secured East and West, and North and South is broadside to the antenna. Because the mounting points was so low, the bottome portion of the antenna was sloped out several feets to help provide space under the antennea for cutting grass.. hi
Results: Actually, the antenna played better than anything that I have had previously. The SWR was flat from 7.0 to 7.1 only rising to 1.5 at 7.3. This was perfect because I wanted it to play RTTY and CW… I did find that the antenna appeared to be less effective broadside, to the North. Stations in New England were difficult to get, however, the Europeans and Western USA were answering on the first call. Also, a few days after the contest, I talked to K4HXW/Mr Tucker, he indicated that he thought the antenna was playing much better than the inverted Vee that I had previously.
Added 31 Aug 2002 Update: I put this antenna back up recently and found that the correct length was a little off on my original antenna. According to ON4UN’s Low Band DXing book, the proper length for a delta loop should be 1.05% to 1.06% wavelength. I used 1.05% and the correct formula to calculate this length in feet is to divide 982.8 by the frequency in Mega Hertz (982.8/7.150=137.45′). I also have changed where the antenna is feed to horizontal by feeding the antenna in the middle of the bottom. This is so that I could have better effectiveness in domestic contest. After several days testing, the antenna seem to work well. Only time will tell… hi hi
Added 17 Oct 2011: Been living in Alabama since 2005 and installed the Delta Loop with the apex at 65′ and the bottom slightly kicked out a bit (not more than 5 degrees). I also changed back to the feed point to 12′ from one of the bottom corners. I really have not been able to see any difference in it performace based on changing the feedpoint. It has worked marvelously both for DX and Domestic contacts. I truly think that it is the best single wire antenna I have ever had on 40m.
I am probably going to put one up for 80m when the WX permits.
Article by KC4HW originally available at http://kc4hw.net/deltaloo.htm
Sooner or later every Shortwave Listener will hear them, the Number Stations: rarely letter-groups are read by a synthezised male or female voice, are keyed in Morse code or are sent in digital mode.
All transmissions start with an identifier/call, usually a 3-figure group, repeated several times. The following figure-groups specify the decryption key/group-count of the message which ends, for example, with a series of “Zero”s (or “out” if spoken).
Every network has its own “fingerprint”: transmission schedule, modulation and format are typical for a specific network and will help the listener assigning it to a certain country. An increasing number of utility listener are into the hunt for Number Stations.
- Use simplex wherever possible freeing the repeater for necessary uses.
- Monitor the repeater (listen) or determine if the repeater is in use, and if there are any peculiarities in its operation. After listening for a few seconds, identify, un key and listen to see if it was quiet for a reason, and to allow someone to let you know if there is a reason not to continue (low audio, low signal strength, etc). Then, if all OK, proceed.
- Donâ€™t break into a contact unless you have something to add. Interrupting is no more polite on the air than it is in person. Interruption without identification constitutes malicious (and illegal) interference.
- Use the minimum power to key up the repeater. To make contact, simply indicate that you are on frequency . For example “IW5EDI monitoring”. Do not kerchunk.
- Remember amateur radio transmissions are being monitored by many non-hams with scanners. Watch your language and your manners. Please don’t bring disrepute on the Amateur Radio Service.
- Repeaters are intended to facilitate mobile and portable operation. During rush hours, base stations should relinquish the repeater to commuting mobiles. Some repeater owners have strict rules requiring this.
- Keep transmissions short and thoughtful. Do not monopolize the repeater. Pause between transmissions to allow other amateurs to identify themselves if they wish to use the repeater. Pausing also allows the timer to reset, avoiding a “time-out”
- Identify legally. In Canada that means at the beginning and end of a contact and every thirty minutes of operation.
- Repeaters are installed and maintained at considerable expense and inconvenience. Regular users of a repeater should financially support the individual or club owner in their efforts to keep the repeater working properly.
This halo antenna by KB1DIGÂ is made with a true Gamma Section this time and is fashioned from aluminum.
Most of the parts are leftovers from old car projects. The best part is it’s omnidirectional!
The 3/8″ fuel-line I used came from Summit Racing Equipment: http://store.summitracing.com #SUM-G2538,
and a 25′ section costs only about $20.oo.
Frank NG1I and Steve N1TYH used aluminum fuel line from a NAPA auto parts supply store.
Welded the elements to the aluminum plate with some of that “Alumaloy” stuff advertised on television.
Alumaloy Sample auctionÂ 1/10 pound or 2 rods of alumaloy aluminum repair rods.
Go to eBay: http://www.ebay.com/Â Key words for search: (SAMPLE) Aluminum REPAIR Rods ALUMALOY
I drilled a small hole in one of the elements to allow condensation to evaporate.
Capped off the end of the gamma arm with a plug to keep the weather out. The plug was an automotive type used to block off a PCV line from a carburetor.
After mounting horizontally to a 10′ mast I added a support system made from 2 thin 3′ fiberglass rods and some wire-ties.
Also, remember to hot-glue the wire-ties to the fiberglass rod.
Both 54″ elements are bolted and welded to the mounting plate.
Use galvanized or some other type of corrosion resistant bolts.
The size of the bolts is not so important other then that they fit snugly into the ends of the 3/8″ fule-line and hold the elements in place while welding the elements to the mounting plate.
This “Alumalloy” product is great for this purpose and is more like soldering than welding.
After the 2 elements are welded, leave the 2 bolts in place for added support.
The so-239 connector is pop-riveted to the mounting plate.Â Face the pop-rivets out and away from the gamma section.
Cut back and expose about 1/4″ of the center conductor of the RG-8 section for soldering to so-239 connector.
Position the 1″ wide aluminum bracket on the Gamma arm, inward about 3 1/2″.
Expose about 3″ of the RG-8 coax center section.
This is just a starting point for matching this antenna.
I was lucky and didn’t need to make any further adjustment for lowering the SWR.Â The SWR on this design seen here, just the way it is, was 1.2 to 1 at 50.125Mhz.
This halo design is intended to be mounted parallel to the ground.
It should work well for base or mobile operation.
I presently use this antenna at my home QTH and it has proven itself to be quite successful for SSB work.Â It is presently up on the roof, mounted to a 10′ mast section in a 3′ tripod stand.
It can also be modified to work on the FM portion of the 6-meter band by shortening the length of the 2 main elements a little at a time.Â I have not done this.Â No change to the gamma arm will be required if this antenna is altered for 6-meter FM.
This article originally available at http://home.comcast.net/~buck0/6m_halo.htm
(C) 1998, 1999, 2000
Â Cubic Quads
Â The cubic quad is a very popular way to get reasonably high gain and excellent front to back ratios as well as low angles of radiation for without going to extreme heights. Here I present several designs that that achieve the great performance that hams have associated with this antenna for years. Data are presented for 2 and 6 meter quads and a combined 2 and 6 meter quad that is optimized. The 2 meter 3 element design gets a great 9.5 dBi gain coupled with a F/B ratio of 23 dB.
Â Light weight portable cubic quads can be constructed rather easily from fiberglass tubes supported by central hubs. You should be familiar with the material presented in the Quad Loop and Pfeiffer Quad sections of the Antenna Magic page. Cubic quads for wavelengths shorter than 15 meters are easily constructed, however, you should be aware that the weight of these structures is larger by a factor of about 3 relative to most of the planar designs presented in the main menu. Because of this, a heavier mast must be used to support the structure in most cases. Also, be aware that the space needed to assemble and raise a full cubic quad is larger than for the planar designs, and this may be a significant limitation imposed in some locations. In my own case, the backyard associated with my town house is barely large enough to assemble a cubic quad with spreaders of 8′ in length. Wires and guy cords get tangled in the fruit trees, and spreaders hang over into neighbor’s yards. Anything larger 8′ with extended spreaders is essentially impossible to assemble without working above the level of the fence and fruit trees. For that reason, I shall present only two designs which are more or less typical of what can be done easily. The two designs presented are for HF and VHF and should be useful to a wide audience. The HF design is a two element quad for 10, 12, and 15 meters while the VHF design is a two element design for 6 meters with three elements for two meters. A specific advantage of the standard quad design is that multi-band operation is easily accommodated.