A Coupling‐Fed Wideband Patch Filtering Antenna With Enhanced Out‐of‐Band Suppression

ABSTRACT This paper proposes a wideband filtering patch antenna with enhanced out‐of‐band suppression. The antenna incorporates a driven patch, two rectangular parasitic patches, and a pair of U‐shaped parasitic patches. It employs a short‐circuited asymmetric fork‐shaped coupled feed line that creates a low‐frequency radiation null. A high‐frequency radiation null is generated by incorporating rectangular parasitic patches, and a new resonant mode is introduced within the passband. Similarly, the pair of U‐shaped parasitic patches introduces another resonant mode, thereby extending the bandwidth. A prototype was fabricated to verify the proposed design, and measurement results confirmed its efficacy. The antenna demonstrated a −10 dB impedance bandwidth of 29% (3.27 to 4.38 GHz), a peak gain of 8.85 dBi, and achieved suppression levels of 25.7 dB in the lower frequency band and 19.14 dB in the higher frequency band. These characteristics make the antenna suitable as a base station antenna for the 5G n77 band.