Abstract
Requirements of test site for EMI measurement above 1GHz are now under consideration. Only free-space condition comes to an agreement. The users of semi-anechoic chambers currently used below 1GHz take a notice to an applicability to use them above 1GHz. We measured the characteristics of a semi-anechoic chamber, and then investigated the requirements to realize a free-space condition by covering the electromagnetic absorbers on the floor. It was found that when interference measurement is performed for a frequency range from 1 to 3GHz and a distance between transmitting and receiving antennas of 3m, while electromagnetic absorbers for widths greater than the first Fresnel zone are installed on the floor of the current semi-anechoic chamber, free-space conditions are satisfied within a precision level of 2dB for horizontal polarized waves and 2.5dB for vertical polarized waves.
