I'm looking for a small improvement in my 40M signal and have the following
thoughts and constraints. I'm currently using an 80/40M trapped vertical
(similar to the BattleCreek Special, without the 160M section) over a limited
set of radials. The yard is fairly small and 80M radials can only cover one
90 degree quadrant.
For the moment, I will do without 80M. I can squeeze in 2 40M verticals with
1/4 wave spacing, but the radials would only cover about 270 degrees around
each vertical. If I use 1/8 wave spacing, I can pretty much cover 360 degrees.
Since I am mostly a DXer, with limited contesting and my location is in San
Diego, the most important directions for me are NE and SW, which is convenient
for locating the verticals. I haven't seen a way to phase 1/8 wave verticals
for a broadside pattern, but I don't really care too much about those
directions. Also, being in the most southwestern corner of the country, I have
no QRM from the SW when I point NE (the ocean is out there) and little QRM from
the NE when I point SW (this is the LP and the sun is up to the east of me).
Consequently, I think working hard for the last couple of dB of F/B is not
So....looking through ON4UN's book, the 1/8 wave spaced array with the
Christman coax feed method seems like a good fit. Does anyone have a better
I also have a couple of specific questions. Are the impedance measurements I
can make with the MFJ259 accurate enough for proper phasing calculations
(including the mutual impedance)? For radials that run between the 2
verticals, should I terminate them in a ground line that bisects the verticals?
Thanks in advance for any thoughts and 73, Bud N7CW
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