Eight-Port Feed Radial Line Slot Antenna for Wireless Power Transmission

This article proposes a circular sector subarray to equalize input power to rectifiers and an eight-port radial line slot antenna (RLSA) with the circular sector subarray. Rectifiers are nonlinear components and have the optimum input power. To maximize RF-DC conversion efficiency, the input power to the rectifiers should be the uniform and optimum input power. The circular sector subarray configuration enables uniform power feeding to multiple ports by dividing the circular aperture into circular sector shapes. The eight-port RLSA has eight microstrip lines to divide the circular aperture to eight circular sector subarrays. The design methodology of the eight-port RLSA is detailed and it is fabricated by printed circuit board technology. The fabricated antenna showed good agreement with the simulated characteristics. Transmission between the eight-port RLSA and a one-port RLSA was measured, and 60% transmission with 280-mm separation was confirmed. Transmission to each port has a 1.4 to 3.4-dB deviation because of the circumference deviation of the one-port antenna aperture distribution. This deviation can be improved by enhancing the uniformity of the one-port antenna aperture distribution.