Low-Cost Broadband and High-Gain Millimeter-Wave Phased Array Based on High-Order-Mode Back-Cavity Slot Antenna

In this communication, a millimeter-wave high-order-mode 1-D phased array with advantages of wide bandwidth, high gain and low cost is proposed for 5G communication. Theoretical analysis proves that the $\textit {TE}_{m10}$ -type high-order-mode back-cavity slot antenna (HOM-BSA) can be utilized to design low-grating-lobe 1-D phased array. Furthermore, through multimode mixing, impedance bandwidth of the HOM-BSA element is extended, and the simulated results can reach 36.73% (27.03–39.19 GHz). For the proof of concept, a 1-D symmetrically arranged phased array composed of the $\textit {TE}_{310}$ HOM-BSA element is demonstrated. The measured −10 dB impedance bandwidth of the prototype array is 35.5% (27.5–39.37 GHz), and the scanning range of less than 3-dB gain variation in the full impedance bandwidth is ±42° (±61° at 28 GHz). Within the scanning range at 39 GHz, the measured sidelobe level (SLL) is less than −8.66 dB, and the measured radiation efficiency is 88.85% at beam direction of $\theta = 0^{\circ } $ . The proposed array is constructed with only one dielectric layer which contributes to low complexity and low cost.