A wideband filtering dense dielectric patch antenna using mutual coupling

A wideband filtering dense dielectric patch antenna (DDPA) is proposed in this paper. Two closely spaced dense dielectric patches are introduced, and their mutual coupling is utilized to suppress undesired higher-order modes and improve the in-band radiation patterns, leading to better main-lobe concentration and lower side radiation. Meanwhile, a Coupled-TE11 mode is generated and merged with the lower-frequency TE11 modes to form a continuous wide impedance passband. A C-shaped open stub is employed to improve the low-frequency excitation condition, enabling an additional TE11-like resonance to be effectively excited and improving the in-band impedance matching. In addition, the metal strips loaded beneath the DDPs and the feeding structure generate multiple radiation nulls near the passband edges, improving filtering selectivity. A prototype was fabricated and tested to verify the proposed design. The measured −10 dB impedance bandwidth is from 4.12 to 5.40 GHz, corresponding to a fractional bandwidth of 26.8%, and the measured average realized gain is 7.82 dBi. The proposed filtering DDPA achieves wide bandwidth, stable radiation patterns, relatively high realized gain, and filtering characteristics.