[VHFcontesting] 6 Meter Antennas

The Greene Family cvgreene at pop.snet.net
Wed Aug 1 21:53:43 EDT 2001

The following are some crackpot ideas about 6 meter antenna systems. 
Take them for what they are worth (keeping in mind what you paid for 

First, in my view, 6 meters is unlike the HF bands where multipath 
propagation can cause problems with choosing the correct wave angle 
for either transmitting or receiving.  It would seem that the best 
approach is to illuminate as much of the scattering medium as you can 
in order to give the best performance at any one time.  Even though 
sporadic E propagation (or F layer for that matter) might not seem to 
be a scatter mode,  it really is as far as the path geometry is 
concerned.  It's only a question of the ionization density.

Based on this geometry, this implies that you want to illuminate the 
"cone" in the chosen direction from as low as you can (1 degree or 
less) up to as much as 10 degrees above the horizon.  Occasionally 
higher angles might be useful, but not for long enough to be 
concerned about for contests.

The problem with high antennas is not so much that their radiation 
angle is too low, but rather that the vertical radiation pattern has 
a whole bunch of nulls between 1 and 10 degrees because the ground 
reflected energy interference.  You can see that effect in the ARRL 
antenna book, or determine it from modelling.  If the signals happen 
to be coming in at an angle where you have a 30 dB null, well, you 
get screwed.

The best antenna systems I've used on 6 meters were designed with all 
this in mind.  Back when W1VD was first set up, I spent a fair amount 
of time with a hand calculator working this out.   Now, with a decent 
pc you can do a much better job in only a few minutes.  That's how 
the W1XX/3 antenna systems used in FN00 were designed.  It's even 
easy to take into account the ground contours for particular location 
when doing the design work.

As far as how W1VD compared to W2SZ, or anyone else for that matter, 
I've never seen any logs but my own, so I can't say.  As far as how 
Spruce Knob in FM08 compares to Blue Knob in FN00, I have someone 
sitting in my living room this very moment who swears that Spruce 
Knob is far superior.  Since I've never been to Spruce Knob, I can't 
say.  But, based on my last experience in FN64 this past June, it 
would seem that given propagation, you can make almost any location 
work pretty well (although perhaps not great) on 6 meters if you 
optimize for that spot.

Clarke  K1JX


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