[Antennas] 40m mobile antenna e.r.p. compared

Sat Apr 30 13:17:44 EDT 2005

Sam Sez...
>>it seems I will get the ok for an
antenna of a size comparable to a mobile antenna 8' to 10'
and
>>My question is, which antenna would have the highest effective radiated
power. (least loss)
Sam... The 8-10 foot requirement is going to seriously limit your choices with
commercial HF verticals. So, you're probably going to have to roll your own or
compromise.
Highest ERP ??
Probably the one with the tallest mechanical height, longest electrical length
(obtain this by using a cap hat), top loading (or as high as practical), and least
coil loss (largest wire-fewest turns). I don't think you're going to find where
anyone has actually done a side by side comparison of shorties. The closest thing
I've found (sold by Champion Radio Products and others) is a book by N0AX and K7LXC
where they do actually test several commercial HF ham band verticals fairly
scientifically and compare results by band. I've done quite a bit of searching for
the answer you seek, and recommend you find and read "stuff" from W8JI, W4RNL,W9UCW,
W2DU, W2FMI,and W7EL. These guys have tons of info on "shortened" verticals (and 5
of those 6 agree!!).
I built and used just such a thing you're asking about last summer when I operated
multi-band HF on a trip to Oregon. Let me know if you would like pictures.
73, Tom AA1NZ