X-Band phase- and amplitude distribution network for phased array antenna measurements

The design and the performance of an X-Band mixed signal PCB with adjustable phases and amplitudes for phased array antenna measurements with up to 32 antenna elements is presented. The implementation of the 6 Bit RF phase- shifters and 5 Bit attenuators within a feeding network will be shown and the digital control functions of FPGA will be explained. The phase- and amplitude calibration of the distribution network was calibrated with by a vector network analyzer and has shown an excellent phase accuracy of ± 1.25° and adequate amplitude accuracy of ± 0.25dB. The proper function of the device was verified at RWTH Aachen compact range. In order to perform these compact range verification tests an X-Band patch antenna array with 32 rectangular elements as AUT (antenna under test) was developed, simulated and built. Finally the compact range measurements are compared to simulations from CST Microwave Studios (CST MWS).