Multibeam Receiving Antennas Employing Generalized Joined Coupler Matrix

Owing to the characteristics of directional couplers, series-fed multibeam receiving antenna arrays require different treatments from their transmitting counterparts. In this article, the theory and strategies for the feed network synthesis of multibeam receiving antennas employing the generalized joined coupler (GJC) matrix are presented. Given M incident waves in any set of directions, we first derive the output signal matrix as a function of the incident signal matrix. This serves as an important tool for both synthesizing and analyzing GJC receiving matrices. Then, we present three different synthesis strategies and show how they are related to the array patterns. We also reveal how the receiving power efficiency of the GJC matrix changes with the antenna beam pattern. We further demonstrate that, despite the employment of matched loads, high receiving power efficiencies can be achieved using the GJC matrix.