Dear Don,
You make some interesting observations here, which I think for QTHs with
relatively good soil conductivity, such as in the UK, hold good in
particular. However, here in WA, on a green belt on the edge of a very
large desert, with rocks, sand and only dry dusty clay at best, I would
argue there are additional drawbacks to inverted-L antennas as compared to
low horizontal dipoles.
Firstly, even with lots of radials (50 in my case) in a time proven
configuration and with apparent relatively low losses in the Fresnel area,
the inverted-L antenna was only better on one very long distance path - on
one particular QSO!. 30 minutes VK6HD (30km away) was working another
station in the same area that I could not even hear!
I really wanted an inverted-L to work, with the idea I could also up a low
dipole elsewhere on the block and get the best of both worlds. Alas, it was
not to be...I have spent several hundred hours putting together verticals
and ground systems over the last couple of years...
Incidentally, my original idea was to use a 3/8 wave inverted-L with a 66'
vertical, as ELNEC indicated this had the vertical pattern of a 1/4 wave and
the horizontal pattern of a low dipole - the best of both worlds in one
antenna. I used an antenna in this configuration, fed via a variety of
methods - L-network, series capacitor and open wire. Although it was a
good-ish high angle radiator, it never seemed as good as the dipole and its
performance as a vertical was very similiar to the 1/4 wave inverted-L.
I guess what I am trying say is it comes down to better overall 'antenna
efficiency' with horizontal rather than vertical antennas at this QTH. I
accept that sometimes vertical polarisation is going to be better than
horizontal - and vice versa. My problem is that I can't get a vertical-type
antenna that works well enough to take advantage of this fact - something I
feel others in dry, rocky situations may also experience. For my QTH, it
seems that horizontal is better 99% of the time.
73,
Steve, VK6VZ
BTW my ground is probably better than most VK6 stations. I have freshwater
springs within a few hundred metres of the antenna. However, the ground is
rock-hard very gravelly clay - bone dry for nine months of the year.
rather than At 10:10 AM 10/20/97 +0100, you wrote:
>Have been watching the discussion with interest. I suspect it's not so much
>vertical vs. horizontal antennas, but high-angle vs. low-angle radiation.
>As such, to be a "big gun" on 160 you really need to be able to cater for
>both, as conditions can vary so much from path to path and from day to day.
>I always recall a particular topband contest some years back (I think it
>was one of those sponsored by 73 Magazine, which used to run 160, 80 and 40
>metre contests). I put up a high inverted-L for DX working, and a low (30ft
>at the centre!) inverted-vee to work the UK and Europe. On night one I
>couldn't raise any W/VE stations on the inverted-L, but almost all of them
>responded first call on the low inverted-vee! On the second night
>everything was back to normal - the inverted-vee worked only for close-in
>stuff, whereas the inverted-L did the trick for DX. I wish now that I had
>noted the solar data for the two nights - it might have been possible to
>draw some conclusions.
>
>Don G3XTT
>
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>
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