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

A gamma match is commonly used to shunt feed a grounded tower at its base. Because the base of a grounded tower is directly connected to the earth, feeding it directly with a standard coaxial cable would short the RF signal to ground. A gamma match solves this by using a rod that extends up the side of the tower, tapping into the tower at a specific height, with a series capacitor placed at the base feed point. This transforms the impedance to match a 50-ohm transmission line while allowing the tower's base to remain physically grounded. Other matching systems serve different purposes. For example, a beta (or hairpin) match is typically used to match the driven element of a Yagi antenna, not a grounded vertical tower.