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Re: [TowerTalk] JK 402 versus CC XM-240

To: towertalk@contesting.com
Subject: Re: [TowerTalk] JK 402 versus CC XM-240
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Tue, 26 Feb 2019 23:02:05 -0800
List-post: <mailto:towertalk@contesting.com>
On 2/26/2019 8:03 PM, Tim Duffy wrote:
With a good ground radial system (very important) here at K3LR - the
full size 4 square holds its own - almost 6 dB of gain over ground -
compared to a stack of W6NL Moxons (185 feet over 120 feet). The
vertical 4 square is a VERY good antenna for 40 meter DXing.

Soil quality also matters a lot for vertically polarized antennas, while it does not matter for horizontal antennas. Radials help verticals ONLY by minimizing losses in the ground they cover; soil quality strongly affects the strength of the far field. K3LC wrote an excellent tutorial on this that was published either in QEX or NCJ something like 10 years ago.

This might, for example, explain why your analysis of the relative effectiveness of your 4-square is different from Jeff's. My QTH in the Santa Cruz Mountains has mostly rocky soil, so horizontally polarized antennas are the winner on all bands except 160M. They're better on 160 because almost any horizontal dipole that could be rigged for 160M is a LOW dipole. :) I had one at about 120 ft for several years when I first moved here, and it rarely beat a Tee vertical with about 80 ft vertical over on-ground radials, and the vertical was usually MUCH better.

One blessing for 160 verticals at my QTH is that the 160M season (winter) is our rainy season, and laying on top of that rock is a lot of "duff," droppings from the trees that act like a big sponge to retain the rain, temporarily improving soil conductivity. Once we've had a lot of rain, my signal gets louder on 160M!

73, Jim K9YC


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