[TowerTalk] More on Half-Wave

[Richard (Rick) Karlquist]

On 1/18/2019 7:44 AM, john at kk9a.com wrote:
> The thread took on a new terrain modeling life but I saw no indication
> that you lived on a mountain top. There is essentially no radiation
> difference between mounting your 40m beam at 63 or 67 ft. I would not try
> to make a tower section out of a mast so I would mount the antenna near
> the top of the tower and use a short mast. It will work fine for domestic
> and DX.
> 
> GL,
> John KK9A
> 

Here's another data point.  I live in the flatlands.  I have A/B'ed a
beam at 40 feet vs a beam at 100 feet with many stations heard on
both beams.  The 100 ft beam has an advantage of 0 dB to maybe 20 dB at
the most.  I have never observed it to be worse than the 40 ft high
beam.  If I make the leap of logic to say that dB are linearly
related to height, then 0-20 dB over 60 feet of height difference
works out such that a 1 dB difference could happen in as little as 3 
feet, but more likely it would take 10 feet to get 1 dB a significant 
amount of the time.  So a difference 4 feet is not worth while.  Better
to get lower loss coax.  I use RG218 on my big tower.

OTOH, mechanically I concur with John:  using a long mast doesn't have
a good cost vs benefit value proposition for a single antenna.  A long
mast is only worth the hassle if antennas for different bands are
being stacked.

73
Rick N6RK