Application of PBG microstrip circuits for enhancing the performance of high‐density substrate patch antennas

We present EM simulation results of a high‐density substrate patch antenna integrated with a microstrip photonic bandgap (PBG) circuit. It is demonstrated that application of such a circuit in an active integrated antenna eliminates undesired high‐order frequency harmonics and patch radiation modes, and improves the return‐loss level at the fundamental‐mode frequency of the patch. Optimization of the PBG periodic element geometry provides harmonics filtering in a wide frequency band. The surface current density on the microstrip PBG circuit integrated antenna has been calculated in illustrating the mechanism of the high‐order radiation harmonics tuning. It is noted that making use of a high‐density dielectric substrate allows easy integration of antenna elements and MMIC circuitry for novel active integrated transmitter front ends.