Antenna with Four Independent Isolated Inputs, Operating with Circular or Linear Polarization

This article discusses an antenna with four independent inputs and dual-polarization panels, allowing four independent groups of transmitters to operate simultaneously. It is shown that the use of dual-polarization antenna panels together with the Butler diagram-forming network allows achieving horizontal-coverage diagram with acceptable nonuniformity, while it becomes possible to operate with both circular and slant polarization. Analysis of the scattering matrix showed that the decoupling between inputs T1-T4, T2-T3 will be determined by the antenna reflection coefficient. The decoupling between inputs T1-T2, T1-T3, T2-T4, T3-T4 does not depend on the antenna reflection coefficient, but in practice it will be determined by the actual decoupling between the 3-dB directional couplers diagonal inputs and the non-uniformity of the power division between the arms, and for typical parameters it will be about 26 dB.