High-efficiency balanced phase-reversal antennas: Principle, bandwidth enhancement, frequency tuning, and beam scanning

Modern wireless systems require low-profile antennas for high integration and low cost. Moreover, balanced antennas with differential configurations have the advantages of easy integration and low cross-polarization. This talk presents a class of novel printed balanced phase-reversal antennas with small lateral footprint and interesting properties. This type of antenna may be regarded as an evolution of Franklin-type antennas. It consists of a plurality of balanced transmission line sections interconnected by phase reversing crossovers having two functions: small dipole radiators and ideal 180° phase shifters. Due to the balanced configuration of the antenna, only the crossovers radiate, and the antenna is subsequently modeled as a serial array of radiation resistances. A six-element coplanar stripline (CPS) array is demonstrated theoretically and experimentally, with measured 9.3 dBi of gain for bidirectional radiation and 12.5 dBi of gain for unidirectional radiation with a back reflector.