Single Layer Cavity-Backed Filtenna with Ultra-Wide Out-of-Band Suppression

A single layer cavity-backed patch Filtenna with ultra-wide out-of-band rejection is presented in this paper. A cavity-backed patch antenna in a single-layer structure is designed and fabricated. It exhibits satisfactory performance of realized gain of 7 dBi at a frequency of 13 GHz. The parallel-coupled lines with capacitive terminations are employed to design a third-order bandpass filter. The capacitive endings in the parallel coupled lines facilitate filter miniaturization and suppression of higher harmonics. The designed antenna and filter are combined to form a Filtenna, demonstrating both functionalities of the antenna and filter. Measurement results of this Filtenna verify its performance, with a return loss of 15 dB and a maximum realized gain of 5 dBi within the 12.8 to 13.2 GHz. Additionally, the designed Filtenna achieves a realized gain suppression of −20 dBi and −10 dBi up to 32 GHz and 46 GHz, respectively.