Test geometry influence on antennas used for MIL-STD-461/462 testing

Investigates the influence of test geometry on the calibration of some antennas used in MIL-STD-461/462 testing. The factors considered are cable placement, antenna position, and antenna alignment. Consistently using the same test geometry can help achieve measurement repeatability. The 1-m separation distance used in MIL-STD testing requires testing in the near field for most antenna types. Because the field varies unpredictably with distance, small changes in the antenna position can have a large effect on the apparent antenna factor. This paper discusses the test geometry and cable placement used by EMCO for 1 m calibrations per ARP-958. This will allow test engineers to duplicate the factory cable placement and thus reduce measurement uncertainty