Improved Field Uniformity Over Metallic Table in Military Radiated Susceptibility Testing by Adjusting Lengths of Antenna Elements and Test Table

The MIL-STD461G RS103 test is one of the essential radiated susceptibility tests for military equipment. Unlike the pre-calibration method of commercial radiated susceptibility tests such as IEC61000-4-3, the RS103 test requires the placement of an electrical field sensor close to the application region of the Equipment Under Test (EUT) and also requires active-leveling of the field based on the feedback from the sensor without use of a pre-calibrated field, which is called close-loop testing. In most cases, the position of the sensor is not certain in the standard and every laboratory uses their own selection for probe positions which should be close to the application region. In this research, we firstly showed that the metallic test table used in the test significantly affects the field uniformity & level achievement over the table. This problem commonly arises in the range of 30 MHz - 100 MHz in the horizontal polarization and almost impedes proper testing due to very high power requirements & poor field uniformity particularly when a high test level such as 200 V/m is targeted. Moreover, this issue also considerably reduces the reproducibility of test results and consistency between laboratories with its probe-position-dependence. This paper firstly sets out the issue that results from the metallic test table and thereafter proposes a solution to the issue by means of the adjustment of radiating elements' lengths of the transmitting antenna and changing the dimensions of the test table, which alleviates the issue and forms a more comfortable test environment over the metallic test table.