Its a receiving antenna. According to its paragraphs in the "Antenna
Engineering Handbook" by Johnson and Jasik (not me), page 11-17,
"Reception depends on the tilt of the arriving vertically polarized
wavefront caused by local ground losses. The electric vector of the
equiphase front, tilted forward, produces a component of electric force
parallel to the wire, inducing a current in the wire This flows toward
the receiver and is reinforced throughout the length of the antenna." It
goes on to say, "Wave tilt increases with frequency and with ground
resistivity. The length of antenna depends on the available land, up to
the limit at which induced currents tend to be out of phase with the
advancing wavefront. Directivity increases with length up to the above
limit."
The Beverage receives in the direction of the wire. A long wire
transmitting antenna has a null in the direction of the wire whether
that wire has a traveling wave or a standing wave and the longer that
transmitting wire, the more the lobes and the closer the strongest lobes
approach the direction of the wire, but there's always that null. The
truth is that the lobes seen in azimuth and elevation around a long wire
are really cones with varying polarization but cones at that angle to
the wire. When the wire is close to the ground much energy gets coupled
to the lossy earth. But the Beverage only works when low to the ground
for receiving.
Since the Beverage depends on a tilt of the advancing wavefront, that's
something the wire can't create as a transmitting wire.
73, Jerry, K0CQ
On 12/5/2010 6:46 PM, Rick - NJ0IP / DJ0IP wrote:
Jerry, can it be that there are too much ground losses due to its close
proximity to ground?
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