High-Gain Filtering DDPA With Metal Cylinders

In this letter, a high-gain filtering dense dielectric patch (DDP) antenna (DDPA) with metal cylinders is proposed, which consists of DDP and double-layered printed circuit boards (PCBs). The
TE
₁₂
mode and
TE
_1+
δ
2
mode of DDP are excited by using a slot feed structure, and form a passband. The proposed filtering DDPA itself has a radiation null at the edge of high-frequency passband. Four metal cylinders inside the upper PCB and DDP introduce another radiation null at the edge of low-frequency passband. When the structure of DDP changes from square to rectangle, multiple high-order harmonics are suppressed or shifted towards high frequency. The high-frequency stopband is widened. By diminishing the upper PCB from large square to small rectangle, the impedance matching and filtering response are improved. A prototype is fabricated and measured for demonstration. The measured results are basically consistent with the simulated ones. The designed filtering DDPA has merits of high realized gain and wide harmonic suppression.