Topband: Low 160m dipoles versus higher ones

[Steve Ireland]

For the last couple of weeks, I have been playing around doing some crude
comparisons between my old inverted-U dipole at 45' (in the centre) and a
new inverted vee at 90' at the apex.

Now, I may be stating the obvious by saying that the new antenna is better
than the old one.  However, I can offer some hope for those who can only
manage a very low dipole for 160m that, on occasions, it may work as almost
well as one much higher for DX around your local sunrise.  

The key here is local sunrise - around which point a lowly situated high
angle radiator can be a reasonable antenna for DX working on 160m, but only
for a fairly short period (ie. five to ten minutes).

This morning, when I worked R1AND in Antarctica at 2253Z - about 22 minutes
before sunrise - I could hear him RST 559 on the high inverted vee, but he
was virtually unreadable/inaudible on the lower antenna.  However, about ten
minutes later, I could copy him at almost the same strength (maybe one 'S'
point less) on the low dipole as on the high one.

The key difference here was that I could copy R1AND for around 15 to 20
minutes on the high antenna, while I only copied him for about 3 - 5 minutes
on the low antenna.  The lower (and thus less efficient) dipole only started
to 'work' when sunrise got closer.

Now, a good operator who was lucky could have worked R1AND on my old
antenna.  It was much easier to work him on the new one, because of the
larger 'window of opportunity' it gave me.

This episode with R1AND is a useful example of a phenomenon I have observed,
not only on my own two antennas, but when I have compared the performance of
my 160m inverted-U dipole with the performance of a fellow VK6's inverted
vee antenna, which is around twice the height of my inverted-U.

Go for the height, but even if you can't get it, all is not lost.


Vy 73,

Steve, VK6VZ





 




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