Design of a low-profile high-selectivity filtering dense dielectric patch antenna

Abstract

In this paper, a filtering dense dielectric patch (DDP) antenna (DDPA) with low-profile and high-selectivity is proposed with thickness of 0.024λ0. By etching an annular gap in the DDP, not only the TM11 mode and TM12 mode are successfully adjusted to the adjacent frequency, but also the high-order harmonics are suppressed. Consequently, both of the operating bandwidth and stopband bandwidth of the proposed DDPA can be enhanced. To improve the skirt selectivity, an adjustable radiation null (RN) is introduced at the lower edge of the passband by using a cross-shaped microstrip feed structure. Due to the mutual coupling between the cylindrical DDP and annular DDP, another adjustable RN is introduced at the upper edge of the passband. Hence, the proposed DDPA can realize the filtering function without additional filtering circuit. For demonstration, a prototype is fabricated and measured. The measured results prove that the proposed design has a relative impedance bandwidth of 8.6% (3.44–3.75 GHz), a peak gain of 8.1 dBi and a high roll-off rate of 180.8 dB/GHz. The proposed design has great application prospects in modern wireless communication system.