E9E09 - Which of the following is used to shunt feed a grounded tower at its base?

Question

Which of the following is used to shunt feed a grounded tower at its base?

Answer Options

  • A) Double-bazooka match
  • B) Beta or hairpin match
  • C) Gamma match
  • D) All these choices are correct

Correct Answer: C


Explanation

Shunt feeding a grounded vertical radiator (like a broadcast or amateur tower) involves feeding the \text{RF} signal into the tower a small distance up from the base, which remains grounded. This is a common and mechanically convenient method to feed vertical antennas, as it avoids the need for complex base insulators.

The most common and effective matching system used to shunt feed a grounded tower at its base is the Gamma match. The Gamma match rod is run parallel to the tower a short distance up from the base. The tap point up the tower acts as an adjustable impedance point, and the use of the grounded base helps to suppress common-mode current on the feed line.


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