Compensation of Free-Space Signal Propagation Errors

摘要

A methodology for minimizing the deleterious scattering effects of absorber cones in an anechoic chamber was modeled and simulated. The concept involved the use of an absorber block which is placed between the source antenna and the antenna undertest (AUT) in the anechoic chamber. A calibration run is made that measures and stores the scattered r.f.. in the chamber with direct propagation to the AUT blocked. The absorber block is removed and the measurement repeated. The data from the calibration run is vectorially subtracted from the second data run yielding the equivalent freespace characteristics of the AUT. The simulation process involved modeling all elements of an anechoic chamber. For this study the Benefield Anechoic Facility was modeled. This included the source antenna, every absorber cone, and a monitoring 'screen' for sensing the E-field at any arbitrary site, or array of sites, in the chamber. The 'screen' data was used to calculate the impact on several modeled antennas. These were a 16 element 30 dB Taylor distribution linear array and an interferometer antenna. It was shown that scattered r.f. from absorber cones greatly effects the ability to measure high performance antennas and could compromise the AOA reading of an interferometer antenna.