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Traveling-wave Antenna for Vertically Polarized TransmissionAuthor: Edmund A. Laport
Figure 3.96 shows the construction of an inverted-V antenna. This is essentially one-half of a rhombic antenna split along its major axis and then turned so that its plane is vertical. In this form, the main lobe of radiation is vertically polarized. The system is structurally simple and uses only one supporting pole.
Circuitally, the inverted-V antenna is unbalanced, the ground forming one side of its input and output circuits. It is desirable to use a system of ground wires at the input end and also at the far end where the antenna is connected to a dissipation line for transmitting or to a resistor for receiving. Its characteristic impedance is one-half that of the equivalent balanced rhombic antenna.
To feed the inverted V, it is usually preferred to use a balanced feeder, similar to those which would be employed for other balanced antennas, and to make a balanced to unbalanced transformation with the proper impedance ratio to excite the antenna. At the terminal end, the dissipation line can be of the unbalanced type, using the ground itself as the dissipator. If the attenuation per unit length is small, owing to high ground conductivity or low operating frequency, the required length of the line may be inconveniently large. In such a case, dissipative conductors will increase the attenuation rate by adding conductor loss to the ground loss.
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