[SADXA] Vertical antenna question

[Ron Jones]

I have a pretty good understanding of this stuff, but I am also willing to admit that I may be wrong. Please, correct me if I'm up in the night. I'm always wanting to learn more. But don't call me any names, we are all in this together to help each other and now and then we goof up.
Here is my reading on this: Bunching your ground radials over to one side will have virtually no effect on directivity. Maybe a bit, but not enough to worry about. You would be better off to spread the radials around evenly. Because of the capacitive coupling between the wires, and other effects, the space between the ground wires acts a bit as a sort of "virtual wire" which sort of makes the ground system look a little bigger than it really is. If you spread the wires out evenly, the whole ground looks bigger than if you have them bunched up on one side. Naturally, those "virtual wires" are not as good as real wires, but you want to get as much ground plane out there as you can. 

On another front, if you have 24 quarter wave ground radials spread out, you have pretty much reached the point of diminishing returns on how many more you need. Yea, the more the better, but you would have to put out a lot more to make any significant difference.

I did a lot with top hat capacitors on low frequency antennas, both modeling and building them, and I found that after about 4 or maybe 6 top hat radials, there was very little improvement. Granted, top hat caps are serving a different purpose than ground radials, but I expect the basic physics of what is going on between the wires is very similar.

That's my two cents worth. Good luck. You will work lots of DX on that vertical with that great ground you have installed.
73
Ron K7RJ





-----Original Message-----
From: SADXA [mailto:sadxa-bounces at mailman.qth.net] On Behalf Of Tom Kramer
Sent: Tuesday, December 29, 2015 1:18 PM
To: CADXA SHARE; SADXA Reflector
Subject: [SADXA] Vertical antenna question

As an extra class I suppose I should know this but, I can’t say I precisely know:

Suppose I have a 1/4 wave vertical antenna set up pretty much in the clear of man-made obstacles and I make a set of 24 radials of about 1/4 wavelength.  I arrange these radials so that they all occupy azimuths of 0 degrees (north) through 180 degrees (south).  

Will this arrangement give the vertical a certain degree of directivity to the east?

If the above statement is true, will this be frequency independent?

Tom NQ7R
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