A review of dipole models for correlating emission measurements made at various EMC test facilities

In this paper we review dipole models for correlating measurements made at various electromagnetic compatibility (EMC) test facilities. We present expressions for the maximum received voltage (at some measurement port) generated by a dipole radiator placed in free-space, an ideal half-space environment, a transmission line, and an over-moded cavity. These different environments correspond to commonly used EMC test facilities, namely, a fully anechoic chamber (FAC), an open area test site (OATS) or a semi-anechoic chamber (SAC), a transverse electromagnetic (TEM) cell or stripline, and a reverberation chamber. These dipole models can then be used as the basis for correlating between emission measurements made at different facility types. Most of these expressions have appeared in previous publications. The purpose of this paper is to present these results in a review having consistent terminology and notation.

1. Introduction

Various types of EMC facilities have been developed over the years to meet a variety of test needs. EMC facilities range from indoor sites to outdoor sites, small volumes to large volumes, and from those possessing precise, well defined fields to those having complex, statistically defined fields. To date, emission standards have been based primarily on the use of the OATS and SAC (e.g., CISPR22, FCC Part 15, Subpart J). However, there is a trend toward additional independent emission and immunity standards that are based on other test facilities. IEC 61000–4-20, covering TEM cell testing, and IEC 61000–4-21, covering reverberation chamber testing, have recently been published. Wark is underway in the IEC to develop an independent standard covering FAC testing. This variety of test methods gives product committees and others the flexibility to choose a test facility that best fits their needs.