Question
Which matching system for Yagi antennas requires the driven element to be insulated from the boom?
Answer Options
- A) Gamma
- B) Beta or hairpin
- C) Shunt-fed
- D) T-match
Correct Answer: B
Explanation
Yagi antennas are often mounted directly to a conductive boom for mechanical support, which complicates the feeding mechanism. Most matching systems (like the Gamma match) are specifically designed to feed an element that is grounded (shunt-fed) to the boom.
However, the Beta or hairpin match is a system that uses an external conductor (the Beta rod or hairpin inductor) connected between the two sides of the driven element. For the Beta/hairpin match to operate correctly, the driven element must be insulated from the boom. This configuration allows the element to operate electrically as a balanced dipole, simplifying the impedance transformation.
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