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Re: Topband: Skywaves from Monopole Surface Waves

To: <topband@contesting.com>
Subject: Re: Topband: Skywaves from Monopole Surface Waves
From: "Richard Fry" <rfry@adams.net>
Reply-to: Richard Fry <rfry@adams.net>
Date: Thu, 4 Oct 2012 08:40:04 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
We need sitting-man-with-meter-in-helicopter to go up there and prove that what you get from the ground up to twenty thousand feet out (at) 20 miles is a blend, and not a notch.

Below is a link to the fields calculated by NEC-4.2 for those conditions, and also for a horizontal distance of 0.1 mile from the monopole.

The plot for a horizontal distance of 20 miles shows the decay in the fields near the earth as a result of earth conductivity along that path, which attenuates the radiated field near the surface of the earth. But those fields are not at or near zero, as some expect when looking at the far-field elevation pattern of a monopole.

The 0.1-mile plot shows maximum field in the horizontal plane, and rapidly reducing fields as the elevation angle increases. This is to be expected for the shape of the radiated field at that distance, which varies approximately as the cosine of the elevation angle.

http://i62.photobucket.com/albums/h85/rfry-100/Surface_Wave_Flds.jpg

R. Fry


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