Filtering Antenna Array Based on Strongly Coupled Radiant Metal Block

This article proposes a novel concept of a strongly coupled radiator that can achieve different phase shift characteristics by choosing different operating states. The strongly coupled structure is realized by introducing a strong coupling in the second-order filter topology, which can be equivalent to two first-order topologies with different phase responses. The topology of strongly coupled radiators and their filtering responses are analyzed in detail. Based on this concept, a strongly coupled radiating metal block antenna is designed, which has the same radiation characteristics as the conventional first-order radiant metal blocks, but with antiphase characteristic. This feature can be utilized to design high-order mode cavity antenna array with low sidelobe and high gain. For verification, a third-order filtering antenna array is designed and fabricated using a TE501 mode cavity, three strongly coupled radiating metal blocks and two conventional radiating metal blocks. The measured results show high gain and low sidelobe level.