UCLA

A proliferation of large active electronically-scanned arrays (AESA) is enabling precise beam steering in wireless communication links at millimeter wave carrier frequencies. In addition to radiated power, linear and nonlinear distortion from the transceivers and array elements must also be examined to discern their relative effects on received signal quality in the far field. For digital signals, error vector magnitude (EVM) represents a complete measure of the amplitude and phase distortion in a wireless channel. This work focuses on the analysis, simulation, and measurement of the EVM resulting from transmission by millimeter-wave antennas and phased arrays. An ultra-wideband (UWB) model of antenna transmission based on the vector effective length is presented and applied to EVM simulation of over-the-air (OTA) links for a microstrip patch and conical horn antenna at two different 5G FR2 bands. The EVM for the conical horn link is measured using a multi-port vector network analyzer (VNA) and compact antenna test range (CATR) provided by Keysight Technologies in Santa Rosa, CA. The same simulation and measurement techniques are then applied to analysis of phased array transmission to understand the effects of beam squint and embedded element frequency response. The EVM of individual active array element channels and the fully-active 8x8 phased array are measured as a function of RF carrier power, far field observation angles, beam scan angles, and modulation rates using MATLAB instrument control scripts. The feasibility of estimating the EVM of far field antenna links from the planar near fields (PNF) is also investigated. A theoretical framework for calculating EVM from wideband far fields derived through PNF transformations and results from PNF simulations and measurements of a Ka-band conical horn and 8x8 phased array are presented. Finally, the effective range of a vehicle-to-infrastructure antenna link at 5.9 GHz is estimated by calculating received power along a linear highway using the Friis free space transmission equation and full-wave simulations of base station and vehicular antenna arrays.