Millimeter-Wave Ultra-Wideband Circularly Polarized OMD Antenna Array Based on Dual-Mode Sequential Rotated Feeding

In this article, a novel ultra-wideband circularly polarized (CP) orthogonal magnetic dipole (OMD) antenna array with a dual-mode sequential rotation feeding (SRF) networks is proposed for the millimeter-wave (mm-wave) applications. Above all, a novel OMD concept model is proposed. Subsequently, based on the conceptual model, a planar CP OMD antenna element is designed and analyzed, and its axial ratio (AR) bandwidth is enhanced by using parasitic patches. To further achieve a wider AR bandwidth and a higher gain, a dual-mode SRF network is proposed and designed to form a $4\times4$ CP antenna array. Finally, the antenna array is fabricated and measured to verify the design. The measurement results of the proposed $4\times4$ CP array show a -10-dB impedance bandwidth of 88.3% (18.15-46.85 GHz) and a 3-dB AR bandwidth of 61.0% (20.5-38.5 GHz) with a peak gain of 16.8 dBic. The proposed antenna array boasts several advantages, such as wide impedance and AR bandwidths and ease of integration, making it suitable for a wide range of applications in fifth-generation (5G) mm-wave communication systems.