A High-Gain, Wide-Stopband Filtering Antenna Based on Cross-Coupling for Mobile Application

In this letter, we present a high-selectivity, high-gain, wide-stopband filtering antenna based on coupling matrix theory. The front end of the filter circuit comprises four coupled resonators, and the slot radiation patch is used as the last-order resonator. Cross-coupling is used to obtain transmission zero, thereby improving the selectivity of the filtering antenna. The spur line structure at the coupling end of the resonator is used to introduce the transmission zero in the stopband. Thus, the effect of high harmonics is suppressed, and a wide stopband is achieved. The simulations agree well with the measurements, which show a peak gain of 8.59 dBi, a radiation efficiency of higher than 90% over the passband (6.425-7.125 GHz) and an extended stopband to 2.58f(0) with attenuation higher than 12.04 dBi. The proposed filtering antenna with high gain, high selectivity, and wide stopband is suitable for mobile communication.