Gentlemen (and Ladies!),
Being new to Topband, I'm trying to educate myself a bit on suitable
transmit antenna system/s for contesting on 160, so as low an angle of
radiation as I can get I'm thinking.....?
An inverted 'L' has been strung up a tree at my QTH, with a 65 foot
vertical section and the remainder tied-off to another tree. The top
section slopes downwards to it's fixing point somewhat (at about 50 foot
or so high) and is parallel to the single radial beneath it at 10 foot
off the ground - like a big 'C' almost. The height above the ground was
chosen so that indigenous wildlife (kangaroos!) don't get tangled-up in
the antenna. The antenna is resonant on 1.845MHz with a good VSWR.
Bandwidth is about 50kHz or so. Performance during the recent CQWW SSB
contest was not up to much however.....
Much debate within the local radio group has taken place as to the
usefulness of radials with an inverted 'L' - some saying it's all a myth
and a single elevated parallel radial would suffice (as is currently
installed), whilst others claim as many radials as you can muster is the
best way forward - regardless of antenna format.
I'm not limited for space as such and my 80m 1/4 wave vertical works
well with many radials on the ground, so to my mind, the 160m system
would require a similar approach and 'more radials is more better'. Or
have I got this wrong?
The inverted 'L' arrangement is obviously different to the 80m 'fully
vertical' arrangement, but I'm thinking that maybe it would be
beneficial to install as many radials on the ground as I can get wire
for and remove the single elevated radial - to mimic the 80m system
format. Is the current arrangement worth augmenting as regards further
elevated radials, or should I just forget elevated radials altogether as
inverted 'L' antennas don't need them as such?
There are other trees (somewhat lower in height) around the antenna
which would support further elevated radials if so desired - possibly
even a 'top hat' if it would help matters.
If you're able to help a fledgling 160m operator and settle a debate
amongst the radio club then it would be much appreciated!
73,
Phil Smeaton
VK4BAA / VK4KW
_______________________________________________
160 meters is a serious band, it should be treated with respect. - TF4M
|