Just found this two old antenna drawings for a four and a seven elements yagi antenna by WB7PMP.
Looks interesting plans but have not yet attempted to build them.
During my recent holidays in Sardinia I’ve been experimenting some portable wire antennas.
Since some years to now, I use to bring with me just a 10m fishing pole and some wires. This year I’ve decided to take with me some thoroids, copper cable, and a solder… and homebrew a balun.
One of the balun I’ve used is the 9:1 balun, an impedance transformer to feed a high impedance, end fed random wire antenna connected to my fishing pole.
These are some schematics I’ve used as reference
I’ve used a T-200 thoroid for my 9:1 Balun, thin copper cable, and a PL coax connector.
The Double Bazooka Antenna is simple to build broadband dipole antenna
Someone consider the double bazooka antenna to offer a 3dB improvement over a common dipole antenna. The only caveat is that an antenna tuner must be used.
The design is easy to replicate and uses common materials. It is mostly made of RG58U coax, #16 automotive wire, rope suspension, and any plastic that can be cut into insulators.
This antenna can been used on 80 through 10 meters by cutting it to the center frequency.
As ARRL member, I love to read QST from time to time.
Honestly it’s the only real advantage of the membership. Being Italian, I can’t really benefit of all club services, and QST is the real added value.
I consider myself a casual reader of QST, since spare time is always very short and time to read magazines is a rarity. But, I love to take QST during my travels abroad. Reading QST in the airplane has become a nice habit.
The last year I wanted to test the Digital Edition only, just to save some bucks.
Unfortunately I did not bring with me the tablet, since I always have with me my own iPhone and the Business Android smart phone, and a third device is really too much.
Well, this week during a travel to France, I decided to download latest issues.
The experience has been very poor, I’m not been able to read a single article, since I’ve found many difficulties on zooming and moving the page to follow the 3 columns format of QST Articles.
Tapping, swiping, pinching open etc has become really a pain, after some minutes I was trying to zoom and move page, to follow the article flow, irritated, I gave up.
I’ve just renewed my yearly ARRL membership asking for the paper QST edition.
I would recommend ARRL to create a Digital edition, with a format suitable for the small mobile devices, and not a simple transposition of the paper format. I do understand it’s much cheaper, but at leat for me, it is a real pain.
By Hubert Scholle, DJ7SH, and Rolf Steins, DL1BBC
The asymmetrical dipole antenna developed and described by Windom (W8GZ) in 1929 has been used by many amateurs for many years as the FD4. This has also been the case in Germany.
We discovered in an older periodical (QRV) the explanation by F. Spillner (DJ2KY) that this antenna, with the addition of a small one-band Windom for 15 m, can be used as a five-band Windom. After the installation of the additional elements, this antenna worked very well for two years at DL1BBC.
With the opening of new bands (10, 18 and 24 MHz), the thought occurred to try out a new extension of the FD4 to eight bands (3.5 to 29.7 MHz).
What worked for 21 MHz must also be possible for 10 MHz.
So we took off the 21-MHz extension to my antenna and hung two elements of 4.69 and 9.38 in (15.39 and 30.77 ft), respectively, on the FD4 and stretched these downwards from insulators as an inverted V (Fig A).
To calculate the length we used the formula:
L/2 = 142.5 ÷ f (Eq A)
Whatever would work for 30 m should also work on 15 m.
As suspected, it worked.
As a by-product, it turned out in the measurements that this double Windom resonated just as well on 18 MHz and 24 MHz. So our eight-band Windom came into being with really simple means.
Thanks to our neighbors, we were able to extend the basic antenna (FD4) to its full length.
At DL1BBC it was installed about 6.9 m (22.63 ft) above the ground, rising to about 8 m (26.25 ft) at each support point. At DJ7SH it hung about 5 m (16.4 ft) above the ground and partly ran over a garage roof. Both extension legs were stretched downwards as an inverted V with an angle of about 100°. Changing this angle allows the whole antenna to be easily tuned during final adjustments.
After construction, the first measurements showed that because of the length of the 30-m elements, the 80, 40 and 20-m bands each had a resonance point that was shifted towards the low end of the band. This effect was eliminated by lengthening slightly the 30-m section, so the resonance points fell more in the middle of the bands.
With this adjustment, the resonance point on 30m shifted slightly towards the end of the band, but this can be tolerated.
With all measurements of the Windom, it was very clear that how the feed line ran played a decisive role.
According to our results, it must be stressed that the feed line must run first vertically downwards from the feed point to the ground and only then to the shack, as otherwise the entire antenna may be detuned. This is especially the case when the height of the antenna is under 10 m (32.8 ft). The 50-ohm-coax feed at DL1BBC was pulled through an old garden hose and then buried under the lawn.
The lower antenna height at DJ7SH had the result that, with the first construction attempt, the precalculated length of the 30-m elements was exactly right. The antenna delivered on all eight bands at the first go.
As can be seen from the SWR charts (Fig B), at DL1BBC the match on 40 m turned out somewhat less favorable. However, this was immediately fixed by changing the antenna height slightly. At DJ7SH, no resonance curve ran above 1.5:1, which was the goal since neither station uses an antenna tuner.
First contacts were made with both antennas. These showed that the antennas had a good degree of performance for a long wire. Especially the downwards sloping extension elements have a clear advantage over the horizontal basic antenna for DX.
With the first try on 30 m, many contacts were made with the US (East and West coasts), with signal reports between S6 and S7 while running 100W.
At present, we cannot make a concrete statement about contacts within Europe.
This article makes no scientific claims, but intends to stimulate the long-wire enthusiast, and especially the friends of CW.
Because the response was unexpectedly great to the publication of the above in cq-DL, we went to work again on an extension, as it was worthwhile to add 160 m.
With a half wavelength at 1.835 MHz, we calculated the basic length of the antenna to be 77.65 m (254.75 ft). We tapped the antenna at 25.88 m (84.9 ft) from one end and fed it with 50-ohm coax through a 6:1 balun. The basic antenna of this length was installed horizontally as a reclining L at DL1BBC. The additional elements, with lengths of 4.69 and 9.38 m (15.39 and 30.77 ft), were attached at the balun. This additional Windom for 10 and 21 MHz was again stretched downwards as an inverted V with an angle of about 100°. Here the additional Windom was mounted so that its elements were not extended in the same direction as those of the reclining L, which gave sufficient decoupling (Figs C and D).
For the feed, the Fritzel company made available for testing a new 6:1 balun, series 83, which can also handle high power. The SWR charts (Fig E) were obtained with the wire lengths given in the preceding paragraph. In case builders experience slight resonance shifts, these can be balanced out by lengthening or shortening the additional Windom.
First contacts were made with the antenna installed at DL1BBC. Here it was once again shown that the antenna has a good degree of performance for a long wire, especially for 1.8 and 3.6 MHz within Europe. The additional Windom again had the degree of performance described in the first part of this article.
The authors welcome questions and exchange of information. (When writing, please include return postage.)
VE2CV, John Belrose and VE3KLO, Peter Boubane.
The reason why I decided this is because, sometime is useful to create public posts, that can be re-shared.
Within my main profile, I have several friend lists with different audience profiles, where I publish posts. Unfortunately posts published to these lists can’t be re-shared public.
So if you wish to connect my ham radio Facebook profile contact me on Facebook
3 Meter Slim-Jim Antenna (JIM = J Intergrated Match) | | <-- spacing: 3" at 72MHz _________ ____ _________ ^ 90 degree --> / \ ^ | copper elbows | | | | | | <-- 1/2" copper pipe elements | | | | | | | | | | ^ | | ^ | | | | | | arrows indicate | 1/2 | | | | | current direction | wave | | | | | | | | | | | | | | | 7.8' (89.5MHz) | | | | | v --> copper sleeve for tuning | | | ---> 3" space air gap _______V | | | ^ | | | | | | | | ^ | | | | | | | | | | | | | 1/4 | v | | | | wave | | | | | * X <-- tap * = center conductor | | | | X = shielding | v_________ \____/ _______v NOTE: Adjust 1/4 wave and 1/2 wave section lengths as follows: 1/2 wave section = 5610/MHz Example: 89.5MHz = 5610/89.5 = 62.68" 1/4 wave section = 2805/MHz 89.5MHz = 2805/89.5 = 31.34" * 1/4 wave freespace = 2953/MHz 89.5MHz = 2953/89.5 = 32.99" * distance that antenna should be from mounting boom, mast, or tower DESCRIPTION: ============ This is a vertically polarized omnidirectional free space antenna which offers approximately 1.8dB of gain. It has a radiation efficiency 50% better than a ground-plane antenna due to its low radiation angle, it is unobtrusive, and has no ground-plane radials - therefore low wind resistance. Why Slim Jim? Well this stems from its slender construction and the use of a 'J' type matching stub (J integrated matching = JIM) that facilitates feeding the antenna at the base thus overcoming and problems of interaction between feeder and antenna. The feed impedance is 50 ohms. Why is the Slim Jim so much more efficient than the popular 5/8 wave or other ground plane antennas, despite the latters claimed 3dB over a dipole? The Slim Jim vertical angle of radiation is almost parallel to ground so maximum radiation is where it is needed: straight out and all round. (The included diagram illustrates that the vertical angle from the SJ is 8 degrees, while the common 5/8th wave ground plane antenna is about 32 degrees. -Steve) With all ground planes, including those with radials an entire wavelength long, the vertical angle radiation is tilted upwards at an angle of 30 degrees or more. This gives the Slim Jim a gain over a 5/8th wave of 6dB when measured parallel to the ground! OPERATION: ========== Basically it is an end-fed folded dipole operated vertically. The matching stub provides a low impedance feed point (50 ohms) at the base and couples to the antenna section at high impedance at one end. As with all folded dipoles, the currents in each leg are in phase, whereas in the matching stub they in phase opposition, so little or no radiation occurs from this. (See diagram for current direction arrows.) Correctly matched, the VSWR (Voltage Standing Wave Ratio -Steve) will be much less than 1.5:1, and remains so across the band. CONSTRUCTION: ============= The Slim Jim should be constructed from 1/2" copper pipe. The bends are made with soldered 90 degree copper elbows. A slip sleave made from copper can be added to the element above the gap for tuning purposes, although the average length of the gap and spacing between the elements is 3" at 72MHz and 1" at 220MHz. No part of the antenna should be grounded to the tower or mast. The recommended mount is the use of PVC pipe and PVC pipe "T's." Make sure the space between the tower or mast and the antenna is one "freespace" 1/4 wavelen. TESTING: ======== Stand upright (on a railing or something, but clear of metal water tanks, drainpipes, etc.) and fit the coaxial cable to the antenna with some crocodile clips. Attach about 2 inches up from the bottom and check the VSWR. Adjust the clips up or down to get the best match (mine managed 1.2:1), mark where they are to go, remove the clips, and solder the coax directly. Use the copper sleeve, if added, for any necessary tuning.
The event want to commemorate the 50th anniversary of the tragic Flood of the Arno river that killed 101 people and damaged or destroyed millions of masterpieces of art and rare books.
With the combined effort of Italian citizens and foreign donors and committees, or angeli del fango (“Mud Angels”), many of these fine works have been restored
A special call sign has been assigned for this event, and will be on air as II5ALL to celebrate this event.
I will take part as Activator with my personal call sing and with IQ5FI club station call as well.
In August, Icom Japan announced during the Tokyo HamFair the IC-7610 HF transceiver, a new mid class amateur radio product.
Successor of the Icom IC 7600, it presents some interesting features like dual watch SDR Receiver, Touch interface and real time FFT.
Icom declared the new radio, hosted in a transparent case, prototype in the R&D phase and the final release date, till today is unknown. As expected, no information on the IC-7610 price range was given.
Practically Icom just announced the intention of a new product, like to say “we are coming” and “works are in progress”.
Ok this can make sense, but, this is not a completely new product. The new transceiver infact is merely a new version of the IC 7600 with the new IC-7300 features in.
This make me a little bit disappointed, since I will never buy an end-of-life IC 7600 today. Although I’m not a marketing expert, the announcement will not reveal to be a good business choice.
Usually, new product announcements includes the expected release dates, that are usually close to the presentation event.
In example in these days, Apple announced the new iPhone 7, that will be available the shops starting next week !
In conclusion, what’s the sense to announce a product in August, that will be available in the store maybe next year in September ?
Who will spend today 3300 euros for an Icom IC-7600 today ?
The real news is that, Icom is clearly working in the direction to deploy SDR technology in all their products.
Probably they had a few bullets to be used for the Tokyo HamFair and they decided to show something in any case, but probably they did not considered the side-effects of a drop in IC-7600 sales.