A High-Gain Filtering DDPA With a Four-Slot Feed Structure Based on High-Order Modes

Abstract

In this letter, a high-gain filtering dense dielectric patch (DDP) antenna (DDPA) based on high-order modes is proposed. The feed structure is composed of four slots and a U-shaped microstrip line. The $TE_{12} $, $TE_{12+ \delta } $, and ${TE}_{13} $ modes of DDP are successfully excited. Based on three high-order modes, the designed filtering DDPA achieves high-gain. Radiation nulls (Null 1 and Null 2) are generated by etching a parallel four-slot structure on the ground and the nonradiative mode. By etching the rectangular grooves on the DDP, using the inverted L-shaped defect structure and attaching the C-shaped stub to the microstrip line, better impedance matching and stopband suppression levels are obtained. In order to confirm the design, the proposed filtering DDPA is fabricated and measured, and the prototype's profile is only ${\text{0.069}}\lambda _{0}$. Measured results indicate that the bandwidth of relative impedance is 13.2% [(4.6 to 5.25) GHz]. The measured average realized gain and peak gain are 8.66 dBi and 9.85 dBi, respectively. The filtering DDPA has high-gain, wide passband, and good edge selectivity.