G'day from Australia
I recently built a roof tower for my 3 element triband beam. The
antenna sits about 6 feet above the roof and about 21 feet (7
meters) above the ground. I realise that this is a total
compromise compared with a tower at a greater height. (I am
trying to keep my neighbours happy).
The results I have found with this set-up are interesting and are
of a concern to me. I have done a lot of comparisons with other
amateurs around me. On 20 meters I would expect the worse
results as the antenna is considerably less than a half
wavelength above the ground. However I receive stations only 2
s-points less than nearby stations with decent antenna setups .
On 10 and 15 meters the antenna performs quite badly with
results down about 6 or 7 s-points compared with my
neighbours. On these bands the antenna is about a half
wavelength above the ground. The SWR is good on all bands.
(Should I be waiting for better propagation, HI)
I guess there could be a lot of factors causing this.
My main question is if I can add about 4 meters (14 feet) to the
height (say 35 feet above ground) will this significantly change
the performance. (I will probably upset the neighbours though).
Can any of you guys with crank up towers lower them to say 20
feet and get a comparison with a incoming signal as compared
with 35 feet. I realise there is so many other factors including
propagation,soil type, trees, angle of radiation , terrain etc etc
that can have an effect. But any general comments about
antennas at low heights would be appreciated.
PS. I am in one of the highest suburbs of Sydney.
73's
Jon VK2JFE
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