Topband: Fwd: radals fer 160m vertcal

[Richard Fry]

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