What is the purpose of a capacitance hat on a mobile antenna?
To increase the power handling capacity of a whip antenna
To reduce radiation resistance
To electrically lengthen a physically short antenna✓Bonne réponse
To lower the radiation angle
Explication
A capacitance hat is a disc or set of spokes near the top of a short whip that adds capacitance to ground at that point, raising the current distribution along the whip and shifting its resonance downward. Electrically the antenna behaves as though it were longer, so less loading inductance is needed and efficiency improves.