Common-mode rejection in a connected array of dipoles with inherent frequency selectivity properties

In this work we describe an effective strategy for the avoidance of common-mode resonances excited in a printed array of loaded dipoles with inherent filtering properties (filtenna). Previous works demonstrated that, for E-plane scanning, such resonances occur due to the unbalanced excitation of the dipoles. The present approach is based on the use of an X-band hybrid-ring connected to the filtenna structure. A design with operational bandwidth spanning from 8.5 to 10.5 GHz is presented and validated with simulations.