Bandwidth-Enhanced Cavity-Backed Magneto-Electric Dipole Antenna

Abstract

A cavity-backed directional magneto-electric dipole antenna with enhanced impedance and gain bandwidths is presented, which is excited by a coaxial balun. The proposed antenna contains a rectangular parasitic element, a modified metal cavity, as well as a bowtie dipole with bending structures. The enhanced impedance and gain bandwidths are achieved by using the rectangular parasitic element and modified cavity. Two pairs of vertical metal plates with different heights and a horizontal metal plate are applied in the modified cavity. In the low-working frequency band, the combination of the bowtie dipole, the horizontal metal plate, and a pair of vertical metal plates with lower height acts as a magnetic dipole, as well as the rectangular parasitic element located above the bowtie dipole functions as a director. A new magnetic dipole is excited by combining the rectangular parasitic element and the bending structures in the high-working frequency band. The experimental results show that the antenna has an impedance bandwidth of 1.38-3.55 GHz (88%) for S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ≤ -15 dB. In addition, low cross-polarization, high front-to-back ratio, stable radiation patterns, and a boresight gain of 9.05 ± 1.01 dBi are obtained in the whole operating band.