Comparison among different feed network topologies for sequential rotated antenna array

This paper presents a comparison among the most used feed network topologies in the context of sequential rotated antenna array design. In particular, the performance of three feed network topologies, i.e., full-parallel, parallel-series, and series, realized with simple T-junctions and quarter-wave transformers, are herein compared in terms of both S11 and axial ratio (AR) bandwidth. Implementation aspects such as the occupied area are also treated. Feed networks are first considered in the isolated case, i.e., in the presence of an ideal constant load, and finally tested in a complete 2 × 2 E-shaped patch antenna array for ultra-high frequency (UHF) radio frequency identification (RFID) reader applications.