4-43
Figure 4-37.—Basic rhombic antenna.
The rhombic antenna is WIDELY used for long-distance, high-frequency transmission and reception.
It is one of the most popular fixed-station antennas because it is very useful in point-to-point
communications.
Advantages
The rhombic antenna is useful over a wide frequency range. Although some changes in gain,
directivity, and characteristic impedance do occur with a change in operating frequency, these changes are
small enough to be neglected.
The rhombic antenna is much easier to construct and maintain than other antennas of comparable
gain and directivity. Only four supporting poles of common heights from 15 to 20 meters are needed for
the antenna.
The rhombic antenna also has the advantage of being noncritical as far as operation and adjustment
are concerned. This is because of the broad frequency characteristics of the antenna.
Still another advantage is that the voltages present on the antenna are much lower than those
produced by the same input power on a resonant antenna. This is particularly important when high
transmitter powers are used or when high-altitude operation is required.
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