Feeding Network with Phase Shifters for a Ka-band Antenna Array

Abstract

This work aims at the development of a feeding network with 5-Bit phase shifters for an active phased array at approximately 30 GHz. Due to the short wavelengths, high packaging density is necessary for the feeding network of an antenna operating in Kaband frequencies. This antenna array has a modular assembly, it is composed of single 4x4 subarrays which are arranged side by side to form the whole array. A modular assembly makes easier the manufacturing of the antenna, since the smaller modules can be manufactured individually and in the same way. Additionally, the maintenance is easier since single modules can be replaced when they fail instead of replacing the whole antenna. To control the 16 phase shifters of a 4x4 subarray, 80 control signals and 16 power supplies are required in addition to the radio frequency (RF) circuit. Due to this complexity, it is started to develop a less extensive 2x2 subarray in this work which will be extended to a 4x4 subarray. Two alternative microstrip feeding circuits for a 2x2 subarray were developed. In order to evaluate the performance of the RF circuits including phase shifters, two printed circuit boards were designed, one for each feeding network. The phase shifters on the printed circuit boards (PCB) can be controlled and the output signals can be measured. In the end it is shown how the 2x2 feeding networks can be extended to form the 4x4 subarray and how those can be assembled to form a phased array antenna.