CHARACTERIZATION OF KA-BAND PHASED ARRAY SYSTEMS: MODELING AND EXPERIMENTAL VERIFICATION

Phased Array Antennas (PAAs), using patch -radiating elements, are projected to transmit data at rates several orders of magnitu de higher than currently offered with reflector -based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA -based links. Short spacing of radiatin g elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2� phase errors can add to Inter - Symbol Interference (ISI), and phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased - array antennas when used in a high data rate modulation link. The system effects created by small increments in the scan angle, as would be experienced during a LEO system passing over a fixed point on the ground, have been simulated in the far field environment and analyzed. Computer simulation of the system under test has also been conducted by creating models using Matlab/Simulink. Variations of the test configuration, including a lower carrier frequency to data rate ratio and various modulation schemes, have been analyzed with these models. The results from the experimentation and simulation will be discussed and the impact for future implementations will be examined.