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Chris asked for detail on my home made inverted V antenna. Really easy to make and use.
For any dipole type antenna remember that it should be 1/2 wavelength long for whatever frequency you will be using. If you feed it with coax then your dipole will be "tuned" for the frequency that you made it for.
468/Frequency in Mhz is 1/2 wavelength. so let's say we want to make a dipole for 40 meters and use it in the voice range around 7.2Mhz. 468/7.2=65 feet. So each side of the dipole should be 32.5 feet long. If it is an inverted V, then it will be slightly less depend on the slope. We can feed this in the middle with coax and it will work. To fine tune, you need to use an antenna analyzer, but if you have an internal tuner in your radio you get to an acceptable SWR.
But what if I want to put up 1 long dipole and be able to tune to more bands? Then we feed with ladder line and use a antenna tuner. The internal tuners probably won't be adequate for this though. The pics below are for my 80 meter inverted V. It is approx 135 feet long end to end. It really doesn't matter as long as it is longer than 1/2 wavelength on the lowest band I want to use. In my case I want to be able to get down to 3.5Mhz so 468/3.5=133.7, close enough. With this I can tune to any band from 10 meter to 80 meters. Because ladder line is 450 ohms and radios like 50 ohms I use a 4-1 Balun and then convert to a short run of coax. Also avoid these lengths of ladder line to avoid harmonics, 66, 135, 190 feet.
Here are the 2 sides
Poor mans eye loop
An insulator made out of plexiglass
Coiled up ladder line
I use banana plugs to connect to balun
4-1 balun with coax output.
Rick, thank you for this post. This is the one I'm really interested in building/duplicating. I've seen your results and I like this very much. It also does not take that long to deploy.
For the time being I'm planning to get a coax (antenna switch) installed in the Jeep so I can easily toggle between the ATAS 120 and a "difference" (second) antenna off the rear.
The "difference" antenna I plan on starting with will be this one that you've shown in this post. I should then put my antenna tuner on this line to be able to tune this antenna to the frequency I'm using, right?
Yes as long as your tuner can tune high swr not just 3-1 or lower.
I thought a 450 ohm ladder-line required a 9-1 balun?
or is it not that simple...
Chris asked a similar question this weekend.
225/4=56.25, pretty close. Also we are using the same wire to tune all bands so we just need to average it.
Short answer is I use a 4-1 balun and it works really well.
ok, I think I'm starting to get it.
Thanks for the reply
I decided not to go with Ladder line. I went with a fan multiband.
Fan dipoles work well also and no tuner needed.