Topband: Radials help

mstangelo at mstangelo at
Fri Feb 10 14:24:00 PST 2012

What radial length does the FCC requirement stipulate for the 120 radials? Quarter, half or a full wavelength?

How did they come to this decision since Brown, Lewis and Eppstein used 0.4wl?

Mike N2MS

----- Original Message -----
From: Guy Olinger K2AV <olinger at>
To: herbs at
Cc: topband at
Sent: Fri, 10 Feb 2012 21:03:26 -0000 (UTC)
Subject: Re: Topband: Radials help

The 120 comes from the watershed 1937 Brown Lewis and Eppstein study now
found in the IEEE journals. There were distinct characteristics to 120
times 0.4 wl (actually 115) that improved results even vs. 60.

That a deficient radial system on one side has any significant reduction in
that direction alone VS THE OTHER DIRECTIONS is a fairly well debunked
idea.  That the missing radials reduce radiation in all directions, due to
diminished efficiency, is not disputed.

73, Guy.

On Fri, Feb 10, 2012 at 2:54 PM, Herb Schoenbohm wrote:

> On 2/10/2012 1:11 PM, Milt -- N5IA wrote:
> > If that is the case, WHY do the pro broadcasters install all 120 radials
> at
> > full length; even bare wire buried a couple of inches underground?
> Answer:
> Because the FCC requires it as part of your AM application.  Some
> stations that were required to protect a distant station on the same
> channel but away from the area they wanted to cover, even applied for a
> waivers with a deliberately poor ground system in the protected
> direction ...but the FCC said no way Jose.  


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