[Lowfer] No luck with - JH

[John Andrews]

Pat,

Those articles were excellent. But I don't recall if they were aimed at 
5 foot verticals on 160 meters or 2.5 foot versions on 80 meters. That's 
the kind of scaling that Garry was talking about. A 50 foot antenna at 
actual LF (185 kHz) is going to be very inefficient with any practical 
ground system for amateur/experimental use. His point was that you can 
only go out just so far on typical house lots or small fields, and the 
concept of diminishing returns seems to come into play.

And since most of us have to put up with nearby houses, trees and 
shrubs, ground wires are only going to help to a certain extent. I 
really don't think that some of this can be modeled well at HF. For 
example, "ground" is mostly resistive at 185 kHz, but has significant 
dielectric properties at 3 MHz. Some of the older literature really 
isn't all that useful - Laporte wrote mostly of large 
commercial/government installations, and George Brown did most of his 
work just below 80 meters.

John, W1TAG

On 12/1/2012 3:31 PM, pbunn at patbunn.com wrote:
> I would recommend reading the excellent QEX articles on radials  that
> were published over the last few years. They did extensive testing with
> short, long and skewed radials as well as elevated radials.
>
> Pat
> N4LTA
>
> -----Original Message----- From: Garry Hess
> Sent: Saturday, December 01, 2012 8:12 PM
> To: lowfer list
> Subject: Re: [Lowfer] No luck with - JH
>
>> Ground rods are not a substitute for radials. At lf,  they need to be
>> as long as you can make them
> and as many as you can afford.
>
> I beg to disagree. Page 3 of The Lowdown, July 1980 article by Ed
> Phillips (available for download at
> http://www.maxmcarter.com/lwantennas/index.html) cites the following
> conclusions of E.A.Laporte's 1952 study of ground systems:
>
> (1) "... radials of length equal to the antenna height are almost as
> good as those of infinite length, and that a length of half the antenna
> height (outside diameter of radial system equal to antenna height) is
> about 2/3 as effective as very great length."
>
> and
>
> (2) "... 2 radials are about half as good as a very large number, and 16
> radials are within a few percent of being as good as 112.
>
> Thus, one need not fear that thousands of feet of radials are necessary
> to produce a lowfer that can be heard out of the back yard. I'm quite
> happy with the performance of my lowfer vertical antenna of 35' height,
> 15' tophat, and 8 x 35' radials (4 of which are terminated by 4' ground
> rods; a pair of 8' ground rods are located at the antenna base).
>
>
>
>
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