Filter theory inspired antenna decoupling technologies

In modern communication systems, the growing challenge of reconciling diminishing spatial resources with increasing wireless performance demands has become increasingly pronounced. The issue of mutual coupling between antennas has garnered widespread attention to accommodate more antennas with reduced spatial resources. Extensive research has been conducted by researchers to address these problems. Different from conventional antenna decoupling techniques, this dissertation presents an innovative investigation of antenna coupling issues from the perspective of filter theory.

This thesis first introduces the background, motivation, and contributions of this work. Then, the general mutual coupling problems and corresponding decoupling techniques are reviewed. To address these problems, multiple novel techniques are presented in this thesis. A hybrid feeding network is presented for achieving two isolated filtering antennas. Cascaded resonator decoupling networks are investigated to provide two isolated antenna channels. Co-synthesis method and steps are provided. Then, a novel concept of designing two slot antennas as a bandstop filter, to achieve self-decoupled antenna ports, is presented. Two low-cost decoupling techniques are presented to decouple two closely placed patch antennas. The first technique is inspired by the electric and magnetic coupling theory in filter design whereas the other technique is inspired by the coupled transmission line theory in filter design.

All contributions have been experimentally validated. These exciting results robustly affirm the practical utility of filter theory in the context of antenna decoupling design, offering valuable insights and directions for antenna design in practice.