A Single‐Layer Miniaturized Endfire Filtering Antenna With Radiation Pattern Reconfigurability

This letter presents the design and implementation of a single‐layer pattern‐reconfigurable endfire filtering antenna. Based on a microstrip quasi‐Yagi structure, the antenna achieves controllable reversal of the end‐fire radiation pattern between the +Z and ‐Z directions by integrating PIN diodes into the radiation enhancement strips. A pair of U‐shaped parasitic strips is placed near the driven element, introducing two additional resonances within the passband to extend the impedance bandwidth and generating a radiation null in the upper stopband to enhance filtering capability. Additionally, a pair of bent parasitic strips is incorporated to create a radiation null in the lower stopband, thereby enhancing out‐of‐band suppression. Measured results demonstrate that the antenna achieves a −10 dB impedance bandwidth of at least 18.1% in both the endfire directions, exhibiting advantages such as single‑layer structure, miniaturized size, favorable radiation performance, and good agreement between simulation and measurement.