Compensation of Free-Space Signal Propagation Errors

A method for minimizing the effects of multipath and other sources of error in anechoic chambers is proposed. The method involves a correction scheme for measuring the vector sum of all sources of undesirable r.f. signals within the anechoic chamber as seen by the antenna under test. This would be done for all angles of concern of the antenna under test (nominally +/-90 degrees). During the initial measurement process, direct radiation from the source antenna to the antenna under test would be absorbed by a specially designed absorber block located between the two antennas. Scattering from the absorber block to the sidewalls of the chamber will be kept to a minimum by the judicious use of absorber material in conjunction with the designed shape of the absorber block. The scattering characteristics of four different absorber block configurations will be modelled as well as the scattering characteristics of all multipath error sources in a typical anechoic chamber. The vector sum of the fields received by the antenna under test with the absorber block in the anechoic chamber and with it removed from the chamber for all angles of concern will be calculated (measured during Phase II). The minimally distorted antenna pattern is calculated by subtracting the first set of data from the second set of data.