The design of a facility to achieve the highest level of field uniformity in the test volume

The most important parameter of any anechoic-shielded chamber used for radiated HIRF testing is field uniformity that can be achieved in the test zone when the System Under Test (SUT) is not present. One of the major difficulties is that it is almost impossible to avoid the presence of large metal structures, such as turntable and hoist, in test volume when large and heavy SUTs are tested. There are so many parameters that affect the degree of field uniformity that in most cases it is impossible to take all of them into account; however it is important to point out that anechoic material does not impact field uniformity to great extent. It becomes important to find out the right trade off among the most important test range parameters, which include (but are limited to): type and size of test antenna, its height above the chamber floor, its distance from the test volume, electric field polarization, size of the test volume and frequency range. The outcome of the simulation or experimental trial is binary (presence or absence of field uniformity) and therefore cannot be easily associated with a numerical scale. Logistic regressions, which is the right method to take into account that type of result, is the optimization tool proposed in this document to design the HIRF test range.