Basic Rules for Indoor Anechoic Chamber Design

E very year, many requests for proposals for an anechoic chamber are generated by companies and institutions that perform antenna measurements. The task of adequately specifying performance for an indoor anechoic chamber without driving unnecessary costs or specifying contradictory requirements requires insight that is not always available to the author of the specification. Although there are some articles and books that address anechoic chamber design [1]–[3], a concise compendium of reference information and rules of thumb on the subject of specifying ranges would be useful. This article intends to be a helpful tool in that regard. It starts by recommending the proper type of range for different antenna types and frequencies of operation. Rules of thumb are provided to select the best approach for the required test or antenna type. Information is provided on the derivations needed for other ranges, such as compact ranges and near-field test facilities. Simple approximations are used for absorber performance to generate a series of charts that can be used as a guide to specify anechoic chamber performance and size. Company and institution facilities can then define the appropriate square footage necessary to house the required antenna range. This article intends to avoid some of the common contradictory requirements. Some of these contradictory requirements are not enough real estate to accommodate a chamber operating at low frequencies or levels that are not possible given available absorber technology.