A compact single-layer filtering patch antenna with wide harmonic suppression and enhanced bandwidth

YY A compact single-layer filtering patch antenna with wide harmonic suppression and enhanced bandwidth is proposed. The filtering antenna is derived from the conventional square patch antenna. To effectively eliminate harmonics and create an upper radiation null, two wide slots are etched on the patch. A shorting via is inserted near the central area of the patch, generating a lower radiation null and improving impedance matching. Combining these two methods, the proposed antenna features good filtering response, harmonic suppression, and broad operating band without size increasing, which satisfies the increasing demand of the integration of multifunctional devices. An optimized prototype is fabricated and measured. The measurements indicate a relative impedance bandwidth of 9.4% with a center frequency (f(0)) of 3.5 GHz and two nulls of 2.78 and 3.9 GHz. High cross-polarization ratio of >20 dB and an upper stopband of up to 2.7f(0) are obtained. To demonstrate the antenna performance in practice application, an array of the proposed antenna is also simulated and discussed.