The link below leads to two graphics showing the __accurately measured__
fields using various numbers of buried radials of 0.274 and 0.412
wavelengths (radial lengths as measured in free space). These graphics show
the groundwave fields for linear, unloaded monopoles up to about 95 degrees
in electrical height. Earth conductivity at that test site in New Jersey
was not higher than 4 mS/m.
The elevation fields of these monopoles varies approximately as the cosine
of the elevation angle. Maximum radiated field always occurs in the
horizontal plane for these electrical heights -- so the greater that field
in the horizontal plane, the greater the field at angles above the
horizontal plane. Pattern shapes for monopoles of these electrical heights
are independent of the operating frequency.
The data show that the system using 113 x 0.412-wave buried radials produces
the highest field, particularly for shorter monopole heights.
It is a judgment call as to what set of buried radials is needed by the
user. AM broadcast stations typically use 120 x 1/4-wave (or longer) buried
radials, but amateur stations may not be able to justify this.
http://i62.photobucket.com/albums/h85/rfry-100/BLandERadials.gif
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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