Not on EMI measurement at open field test site-effect of EUT shelter

It was reported previously (see A. Maeda, 1988) that a shelter placed over the ground plane and equipment under test (EUT) causes degradation of the site characteristics. Degradation is not shown by usual site attenuation measurements but is apparently with height pattern slots of site attenuation. Measurements are presented which show that degradation becomes noticeable at frequencies above 200 MHz, and large above 400 MHz, even though the shelter was fabricated with materials and techniques commonly used for randomes. Laterally translating and rotating the measurement axis with respect to the EUT shelter axis solves the problem.<>