What is the purpose of the series capacitor in a gamma match?
To provide DC isolation between the feed line and the antenna
To cancel unwanted inductive reactance✓Correct answer
To provide a rejection notch that prevents the radiation of harmonics
To transform the antenna impedance to a higher value
Explanation
The gamma rod together with the section of driven element it parallels behaves as a shorted stub, so the match by itself leaves the feed point looking inductive. A capacitor in series with the gamma rod supplies an equal and opposite reactance, leaving a resistive feed point at the desired value.