[Lowfer] No luck with - JH

[John Andrews]

Pat,

Just one additional thought - I wouldn't use 5 foot radials either! But 
the issue for most of us is that our land doesn't scale with the 
wavelengths we use. I could only dream about radials a couple hundred 
feet long. Of course, that's part of the reason that I've stuck with 
loops in all these nasty trees.

John, W1TAG

On 12/1/2012 4:31 PM, pbunn at patbunn.com wrote:
> John,
>
> I agree that some of the test data is not scalable, but I do not agree
> that radials should be limited to the height of the antenna (especially
> if it is 5 feet high) nor do I agree that two radials is half as good as
> many. If that were the case, I'd double my power and forget about it.
>
> I was trying to get the point across to John is that one 8' ground rod
> and 4 -  5' rods will not be very effective. He needs some radials and
> if he adds some he will improve his ERP. I certainly was not telling him
> he needed 2000 foot length radials - "as long as you can make them" for
> most people is a couple hundred feet.
>
>
>
> Pat Bunn
> N4LTA
>
>
>
> -----Original Message----- From: John Andrews
> Sent: Saturday, December 01, 2012 9:26 PM
> To: Discussion of the Lowfer (US, European, &UK) and MedFer bands
> Subject: Re: [Lowfer] No luck with - JH
>
> 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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