On Oct 4, 11:01 am, "michel" wrote:


In my search on vertical antennas I also found a option to add on a 1/4 wave
element a 5/8 element. This needs a phasing coil?
I also found a 5/8 element mounted over a 1/4 innerelement.. ?

But wat is the best for homebrew, and a few dB gain?

With VHF verticals, half the battle is decoupling the feedline.
It's no use worrying about extended verticals, unless you also
consider decoupling the line. Radiation from the line will skew
the pattern upwards off the horizon, and any gain from extended
radiators will be useless.
If you are going to use a 5/8 radiator, I would go whole hog and
build a copper collinear with dual 5/8 elements. I wouldn't waste time
with other versions. And even the dual 5/8 collinear needs a
decoupling section of some type.
One reason I like the 1/4 wave ground planes is that they naturally
decouple from the feedline fairly well. The more radials you use,
the better the decoupling, and if you add a 2nd set that is 1/4
below, you will have very good decoupling.
That method can be used to decouple a dual 5/8 vertical.
I would worry more about how the line will be decoupled, than
I would element length. It's more important.
MK