A High-Efficiency SISL-Based Slot Antenna Array for Wireless Power Transmission Application

A high-efficiency slot antenna array based on substrate integrated suspended line (SISL) technology operating at 24 GHz is presented for wireless power transmission (WPT) application. Because of the feature of self-shielding and low loss of SISL technology, double-side SISL (DSISL) is used to further reduce substrate and conductor loss in antenna design. Besides, four radiating slots are etched on the top ground layer of DSISL and serially fed as a subarray without any extra feeding network. By utilizing DSISL and avoiding network loss, a high efficiency subarray is realized with simulated efficiency of up to 89% at 24 GHz. In addition, the subarray is fabricated and measured. The measured results of subarray show that the 10 dB impedance bandwidth is from 23.75 to 24.1 GHz, which covers the WPT band (24 GHz ± 100 MHz). The measured gain of 13.1 dBi and radiation efficiency of 83.5% is achieved at 24 GHz. Besides, the width of air cavities can be further reduced to 0.384λ
₀
(λ
₀
is the free space wavelength at 24 GHz), benefiting from the basic mode tangential electromagnetic (TEM) mode of DSISL, which is good for wide scanning phased array design. Based on the subarray, a 1×8 phased array is designed and fabricated. The measured results show that |S
₁₁
| of −32 dB, isolation of 19 dB, and gain of 19.5 dBi is obtained at 24 GHz, while a wide scanning range of ±50°with gain drop less than 3.3 dB is achieved also at 24 GHz.