A high gain circularly polarised magnetoelectric dipole antenna array with metallic radiating structures for millimetre‐wave applications

Abstract

An antenna array design method of trade‐off between high gain and low profile is proposed. A high‐gain circularly polarised (CP) substrate integrated waveguide (SIW)‐fed magnetoelectric dipole (ME‐dipole) antenna array with metallic radiating structures is presented for millimetre‐wave (MMW) applications. The CP antenna element comprises a set of horizontally and vertically metal plates and a metallic cavity that is excited by an X‐shaped coupling slot etched on the broader side of SIW. The metallic cavity is designed to improve the gain and axial ratio (AR) performances. Utilising this antenna element, a proof‐of‐concept is established through the design of a 2 × 2 subarray and a 4 × 4 array. The fabricated 4 × 4 CP antenna array has a measured impedance bandwidth of 6.1% (36.4–38.7 GHz), with |S₁₁| ≤ −10dB. The measured 3dB AR bandwidth is 5.4% (36.0–38.0 GHz). The measured maximum gain achieved is 19.1 dBic. The height of the proposed array is 0.74λ₀ which is larger than the heights of typical SIW‐based microstrip arrays (0.1–0.4λ₀) and lower than the heights of metallic arrays (larger than 2λ₀).