Wideband Circularly Polarized Magneto-Electric Dipole 1×2 Antenna Array for Millimeter-Wave Applications

A novel wideband circularly polarized (CP) magneto-electric (ME) dipole $1\times 2$ antenna array for millimeter-wave applications is presented in this paper. The magneto-electric dipole of a single radiator is designed by combining a pair of loaded short-circuited metallic patches acting as electric dipole with a bowtie-shape aperture and a pair of vertical metallic posts functioned as a magnetic dipole. The pair of metallic patches is fed by the bowtie-shape aperture etched on the top surface of shorted-end substrate integrated waveguide (SIW). By chamfering and adding perturbation on each rectangular patch, the proposed ME dipole antenna realizes circular polarization radiation. Measured results show that the proposed single radiator has an impedance bandwidth of 27.1% (24.29 to 31.9GHz) for S11<−10dB, an axial-ratio (AR) bandwidth of 9.7% (27.4 to 30.2GHz) for AR<3dB, and a stable gain of 7dBic. In order to extend AR bandwidth, the array antenna is implemented in a $1\times 2$ arrangement and fed by a complementary SIW power distribution phase shifter. The proposed antenna has a simple structure and can be realized by PCB process, which is very convenient for mass production. Measured results demonstrate that the proposed $1\times 2$ antenna array has a wide impedance bandwidth of 25% for S11<−10dB, a stable gain of 10dBic and an axial-ratio bandwidth of 24.7% for AR<3dB, which is 2.4 times higher than the 3-dB AR bandwidth of a single radiator.