One end of loss-less transmission line having the characteristic impedance of 75 $$\Omega $$ and length of 1 cm is short-ciruited. At 3 GHz, the input impedance at the other end of the transmission line is

At 20 GHz, the gain of a parabolic dish antenna of 1 meter diameter and 70% efficiency is

For a Hertz dipole antenna, the half power beam width (HPBW) in the E-plane is

A rectangular waveguide of internal dimensions (a = 4 cm and b = 3 cm ) is to be operated in $$T{E_{11}}$$ mode. The minimum operating frequency is