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Ground Plane Radials

January 30th Fact-of-the-Day

The number of ground plane antenna radials needed for efficient operation depends on the height in wavelengths of the ground plane above ground. Nearly all the electric field from the vertical radiator will return to as few as three of four ground plane radials if the radials are high above ground. However, if the radials are at ground level as many as 180 radials are needed for highly efficient operation, because otherwise a significant percentage of the electric field will pass between the radials and return through comparatively high-resistance soil. The number of radials required for high efficiency diminishes rapidly with radial height above ground, such that at a radial height of one-quarter wavelength eight to ten generally are adequate. ©2005 Martek International All rights reserved.


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