A Novel Filtering Antenna via Electric and Magnetic Coupling on a Transversal Topology

In this article, a novel filtering antenna based on a transversal topology is presented. The design incorporates both electric coupling (EC) and magnetic coupling (MC) feeding techniques. By leveraging their distinct phase characteristics, an out-of-phase condition is created in the stopband to generate out-of-band radiation nulls, while an in-phase condition is maintained in the passband to prevent radiation cancellation. The integration of both feeding schemes into the transversal layout yields a simple and compact structure without extra feeding circuits. Furthermore, λ/4-length patch elements are adopted, whose opened and shorted ends facilitate EC and MC feeding, respectively, allowing a single radiator type to support dual excitation and further simplify the geometry. A synthesis approach is applied to align the radiation quality factor of each element with the filter's external quality factor, enabling flexible adjustment of fractional bandwidth and radiation null locations. A third-order antenna prototype with dual stopband zeros is in final designed, fabricated, and measured, exhibiting well-defined filtering performance, a compact single-layer profile, and promising practicality for modern wireless systems.