G5RV versus a Fan Dipole

[WB2WIK]

Louis Varney, G5RV, didn't consider it to be a problem. He picked the original 102 foot, 1.5 wavelength on 20m, specifically because of the four major lobes in the 20m radiation pattern which were the four directions that he wanted to cover from his British QTH. One man's problem is another man's solution.

One doesn't have to work too long in an engineering lab before he hears the phrase, "If you can't fix it, feature it."

Toyota engineering lab: "The car is programmed to go faster sometimes, when driver least expect. This is feature to awaken sleepy driver."

[KA4DPO]

One doesn't have to work too long in an engineering lab before he hears the phrase, "If you can't fix it, feature it."

Toyota engineering lab: "The car is programmed to go faster sometimes, when driver least expect. This is feature to awaken sleepy driver."

Also, when car speed up brake not work. This is special feature to assist constipated driver.

[K1DNR]

When I was a kid, I needed a vertical for 2 meter FM with some gain to hit a repeater that was about 45 miles or so away. I didn't have any money to spend. I didn't know how to measure coils or make a 5/8ths wave.

So I started experimenting and I found that 60" of wire loaded with a very good SWR. I knew enough to realize that was 3/4 wavelength.

So I stuck an SO-239 on a coffee can, screwed in some aluminum grounding wires as radials, and stuck the 60" aluminum grounding wire into the SO-239. Somehow it managed to stay put and stay upright. Must not have been much wind.

It worked and got me into that machine, however my signal into lots of other machines got worse...

Of course there was no EZNEC back then :-) But modeling the antenna now I can see exactly why!

[VK1OD]

...
So I started experimenting and I found that 60" of wire loaded with a very good SWR. I knew enough to realize that was 3/4 wavelength.

So, you now probably know that a 3/4 wave vertical ground plane has low low angle gain, much poorer than a 1/4 wave.

If it worked better on some path, that is interesting, but unusual.

I lived for a long time in an area where the main repeaters were on a high mountain (for Australia) about 35km away. I would often leave a 2m quarter wave on the roof for working the 70cm repeater, but is was appalling compared to a 70cm quarter wave when used. When out of town, the only way to work the 70cm repeater was to use a 70cm quarter wave or better, certainly not the 2m quarter wave.

I now live in an area where I can often work repeaters in the range 75 to more than 150km away (~50mi to 100mi+) from the car, but not using a 3/4 wave vertical... though a 5/8 works very well.

It is just another case where acceptable VSWR doesn't of itself indicate good performance.

Owen

[WB2WIK]

It is just another case where acceptable VSWR doesn't of itself indicate good performance.

Low SWR is always great.

I have an 80 meter inverted vee that has an SWR of <1.2 at 146 MHz! Simple setup: Rig -> 300' RG58A/U -> 80m inverted vee!

[K1DNR]

So, you now probably know that a 3/4 wave vertical ground plane has low low angle gain, much poorer than a 1/4 wave.

If it worked better on some path, that is interesting, but unusual.

I lived for a long time in an area where the main repeaters were on a high mountain (for Australia) about 35km away. I would often leave a 2m quarter wave on the roof for working the 70cm repeater, but is was appalling compared to a 70cm quarter wave when used. When out of town, the only way to work the 70cm repeater was to use a 70cm quarter wave or better, certainly not the 2m quarter wave.

I now live in an area where I can often work repeaters in the range 75 to more than 150km away (~50mi to 100mi+) from the car, but not using a 3/4 wave vertical... though a 5/8 works very well.

It is just another case where acceptable VSWR doesn't of itself indicate good performance.

Owen

It was a terrible antenna overall of course. It did show a significant amount of improvement in that particular direction, and that particular path - whatever it may have been. it was terrible on just about everything else.

It would have been simpler to build J-pole, but this is not something I was aware of... This was probably about 30 years ago and I was 14 years old.

[VK1OD]

Charley,

Mistakes or things that don't work properly or well are an opportunity to learn. Those of use who have learned lots have probably made lots of mistakes.

But, I am still a bit hard on myself if I make the same mistake twice!

Owen