[CQ-Contest] Contest QTH, hilltop or seaside?

[Yuri Blanarovich]

Hilltop vs. flat land enhances and lowers the TOA, which roughly 
tribander at 60 - 80 ft is close in performance to 2 or 3 stack at 200 
ft. Plus the hill - elevation brings one closer to the propagating 
layers and less noise. There was W3??? in the past with tribander on a 
hill that was dominating 20m.

Oceanfront, salty ground typically ads about 15 dB especially with 
verticals. Low angle, close to horizon, on RX and TX plus no noise 
sources from the ocean, can't be beaten. Just get into the mobile and 
drive around, in and out from the beach or on the bridge over salty 
water. Like driving into the amplifier.

It took me while to realize that:

1. Antenna system - design, configuration, shapes the pattern and 
contributes to efficiency of converting energy from the coax to be 
radiated. Radiator with elevated radials in resonant antenna is good 
example.

2. "Mirror" - Environment in which antenna system is positioned affects 
the performance, efficiency and pattern shaping. Ground conductivity, 
terrain, obstacles can have detrimental effect, distort or enhance 
performance of antenna system. Picture light source and various mirrors, 
from perfectly reflecting one, to "spongy", to absorbing one.

For example on low bands and 160, RF penetration into the ground is 
deep. Portion of RF gets "eaten" by lossy dirt, rest is participating in 
pattern forming. Remedy is to use elevated radials and have extensive 
screen or radial field, as large as possible, to reflect the RF rather 
than have it "eaten".
This is where some confusion about buried radials and number of them is 
so live. Transition from few radials - antenna part to many - ground 
screen/mirror. One has to distinguish between the "mirror" vs. antenna - 
signal source and their mutual interaction. This is where salty water 
shines, it is almost perfect mirror, with hardly any penetration, in 
perfect harmony with RF radiator. I used to water the lawn before the 
contest.

At old AT&T WOO site, the radio engineers in the thirties designed 
conical monopoles sitting in the salty marsh by having base of antenna 
elevated about 4 ft, about 30 radials going out in the air for about 15 
ft to wooden "fence" and then dropping into the salty marsh. Whole 
antenna field (abt 200 acres) is flooded through channels at high tide, 
with portion of water evaporating and slowly increasing salt 
concentration. S-meter on 160 sits at 1.

Buildings, power lines, trees can distort the "mirror" further and have 
impact on antennas and pattern forming. Back in Toronto we have seen 
dramatic effect of huge power line corridor, typically 2 - 3 S-units, 
between  my and VE3FFA QTH, being on opposite sides of the wires.

Keeping in mind that we are dealing with "light," it's beam shaping and 
"mirror" helps to realize the important factors in the RF radiation 
efficiency and beam shaping.

Happy and prosperous 2015!

Yuri, K3BU.us



 
 
 On Thu, Jan 01, 2015 at 10:46 PM, ScottW3TX at verizon.net wrote:
 
 > Is there an argument to be made for favoring plain vanilla flat land 
in all directions, instead of a hill or mountaintop, so that the TOA's 
can be optimized for all bands by antenna height/stacking for all 
important directions?
>
> Best regards,
> Scott w3tx
>
> On Jan 1, 2015, at 8:25 PM, "Ed Sawyer"  wrote:
>
> Go with the hilltop.  The oceanfront is great if you have unobstructed 
> low
> angle in a few favored directions.  But oceanfront with low angles cut 
> off
> is not a good compromise.
>
>
>
> Spend A LOT of time with HFTA after carefully detailing the terrain 
> within
> 1000ft of the antennas.  My best antennas are all 25 - 30 ft to Europe 
> off
> the side of my hill to Europe.
>
>
>
> Ed  N1UR
>
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