A Novel Feeding Network for Quadri-Polarization Antennas With Simultaneously Wide Impedance and Polarization Bandwidth

In this communication, a broadband feeding network for quadri-polarization antennas has been proposed. The feeding network is composed of several passive components, namely two Wilkinson power dividers, slow-wave transmission lines, Schiffman phase shifters, branch-line hybrids, and a crossover. With a careful design of each component and an elaborate topology arrangement, the four output ports can transmit signals for antennas with four polarization states in a wideband, i.e., left-hand circular polarization, right-hand circular polarization, +45 degrees and -45 degrees linear polarization. Two antenna implementations based on such a feeding network have been given, and the measured results show that antennas have a bandwidth as wide as 22.7%, within which excellent input port impedance matching, port isolation, realized gain, and polarization purity are simultaneously achieved. The feeding network also has advantages such as completely switch-free, ease of fabrication and implementation, and flexibility for different types of antenna configurations.