Radiation properties of coaxial colinear antennas

A single coaxial colinear antenna is considered as a base station antenna for personal communication systems due to its low cost and structural simplicity. It consists of several segments of half-wavelength coaxial cables where the inner conductor of one cable is electrically connected to the outer conductor of the adjacent one. The intent is to have the excitation voltages across all the slots in phase and equal in magnitude so that a stronger in-phase current distribution can be driven on the outer surface of the coaxial cable to obtain a high gain in the broadside direction.