Millimeter-Wave Broadband Dual-Polarized Shorted Patch-Loaded Magnetoelectric-Dipole Antenna and Its Array

Abstract

A broadband dual-polarized antenna is proposed for millimeter-wave (mmW) application, which is composed of two pairs of magnetoelectric (ME) dipoles and a shorted patch. The ME dipoles are arranged into a square ring shape to enclose the shorted patch to generate multiple resonances, and they are fed through a cross-shaped slot by two orthogonally placed feeding strip lines for dual-polarization. The proposed antenna is fabricated and measured, which achieves an impedance bandwidth of 65.4% (21.3–42 GHz) for dual-polarization, with an in-band gain variation of less than 1 dB. A $1\times 8$ array is further designed and implemented using two substrate-integrated coaxial line (SICL) feeding networks to excite eight uniformly distributed elements. The measured results show that an impedance bandwidth of 58.75% (22.1–40.48 GHz) is achieved for dual-polarization, accompanying a peak gain of 15 dBi and gain fluctuation smaller than 3 dB. To break through the beam scanning limitation over the achieved octave bandwidth, an offset feeding scheme is introduced to the proposed antenna, and a small-scale $1\times 4$ nonuniformly arranged array is proposed and numerically analyzed. The measured results indicate that a beam scanning range of ±30° can be achieved over the entire operating bandwidth, and the sidelobe levels (SLLs) remain below −10.46, −11.5, and −10.16 dB at 22, 30, and 38 GHz, respectively. The proposed antenna and its array have features of broad bandwidth, flat gain, stable radiation pattern, and wide-angle scanning, which are promising for mmW communication systems.