[Top] [All Lists]

Re: [TenTec] OT: Indoor Antenna

To: ken.d.brown@hawaiiantel.net
Subject: Re: [TenTec] OT: Indoor Antenna
From: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Reply-to: geraldj@weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 03 Dec 2010 08:16:56 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
Precisely, and the bandwidth of that match with the ground rod will be 
much wider than with a radial system.

10 ohms is a very good ground rod, and one driven into basement fill is 
likely to be considerably higher in resistance at RF and at DC. Dirt is 
a poor conductor, just for AC and DC there's so much of it in parallel 
that the impedance over a distance is low, but locally its rotten stuff 
for conductivity unless its a salt marsh swamp.

73, Jerry, K0CQ

On 12/3/2010 1:01 AM, Ken Brown wrote:
> A quarter wavelength monopole with a really good counterpoise/ ground
> radial system has a feed point radiation resistance of around 37 ohms
> and very little loss resistance. That will give you an SWR of about
> 1.4:1. If you use just a ground rod and have about 13 ohms of resistive
> loss in the ground system, the series equivalent feed point impedance
> will be about 50 ohms, and the SWR will be very near 1:1. Some people
> think this is better. It does "tend to make the matching easier."
> I don't know what kind of ground you have, or whether your ground system
> resistance would be 13 ohms with just a ground rod. The point I am
> trying to make is that a really efficient vertical is likely to have a
> higher SWR than a partially radiating dummy load. Many hams do choose a
> lower SWR over a more efficient radiator.
>> The ground rod will work, but it will introduce more resistance to the
>> antenna feed than radials. It will tend to make the matching easier, but
>> the efficiency poorer.
TenTec mailing list

<Prev in Thread] Current Thread [Next in Thread>