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Re: [TowerTalk] Radials Questions - 270 or 360 degrees.

To: Red <>
Subject: Re: [TowerTalk] Radials Questions - 270 or 360 degrees.
From: Bill Coleman <>
Date: Wed, 5 Jan 2005 19:08:11 -0500
List-post: <>

On Jan 5, 2005, at 11:50 AM, Red wrote:

EZNEC modeling indicates a very slight assymetry and reduction of gain resulting from omitting 90 degrees segment of the radials. Both figures are within the inaccuracies associated with errors and assumptions in the modeling.

Is 1.1 dB considered very slight?

The assymetry, 1.1 dB, can be reduced to 0.2 dB by removing the opposing 90 degrees of radials, at the cost of about 0.5 dB of maximum gain.

This doesn't seem like a good idea, then. The net change would be to increase the gain in the assymmetric direction by 0.3 dB, at the cost of 0.5 dB elsewhere in the circle....

The performance will benefit some from using more radials, even if, in the interest of limiting the amount of wire used, some are shorter than 60 feet. However, variables associated with modeling errors, assumptions of ground characteristics, terrain features, wires and pipes in the structure, etc. are generally greater than the calculated differences in performance. Put down as many radials as you can and don't worry much about the 90 degree gap. If you can fill the gap without introducing excess interference or complexity, do it.

Well, that about answers my first question -- how about the other three questions?

Question 2: In looking at option B, is the vertical segment going to have an adverse effect on the pattern in the NW to NE direction? Is the vertical segment going to change the phase of the currents and ultimately destroy any gains by adding the radials?

Question 3: Is there any coupling or danger associated with having these radials inside the house? Is there a potential for high voltages to appear, or to have the elements radiating RF inside the structure? Is this different from option A or B?

Question 4: Of the three options (A, B or do nothing) which offers the best possibility of improving the antenna efficiency or evening out the radiated pattern of the vertical? What would you recommend and why?

Bill Coleman, AA4LR, PP-ASEL Mail: Quote: "Not within a thousand years will man ever fly!" -- Wilbur Wright, 1901


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