|Subject:||RE: Topband: Adding radials, a question|
|From:||"Richard Detweiler" <firstname.lastname@example.org>|
|Date:||Thu, 02 Sep 2004 12:34:20 -0500|
While I am no expert on the issue of radials, There are many good articals, I've found some of the best about vertical theory in dealing with the Butternutt Verticals.
http://www.bencher.com/pdf_download.html ( at the bottom of this page is a very good section on Vertical theory under Tech Notes )
As I understand it for ground mounted verticals, as you put in more radials, the 'Q' gets higher. Especially for for low bands (160 & 80) Thus as the radials increase, the radiation resistance increases ( the good kind ) and and the ground loss or ground resistance decreases ( the bad kind ). Excuse my teminoligy here. So the total resistance approaches the more perfect 35 ohm vertical impedence. Obviously, it can never be fully acheived but the point is this, when the Q stops rising appreciably, you've probably put in enough radials for the amount of wire you have in the air.
Of important note here is that the length of the radial isn't really important as the ground detunes them, but the need to be somewhere about as long as the height fo the vertical.
The way I measued was to see how wide the 2:1 SWR frequency band width using 259 analyzer. The more narrow the 2:1 width, the better the radiation resistance will be. Then use a small amount of power, 20 to 50 watts to double check. The 259 is very suseptable to AM radio stations at those frequencies even if they are not near by.
In my case the best answer was 40 radial going out 30 feet 9 degrees apart.
All of this changes fairly significantly when the vertical is raised above ground. So keep that in mind.
Best 73's Rich K5SF
From: W5UN <email@example.com> To: firstname.lastname@example.org Subject: Topband: Adding radials, a question Date: Thu, 02 Sep 2004 00:14:36 +0000
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