The history of the SAM head phantom

SAM - the Standard Anthropomorphic Model - is a head shell phantom intended primarily for use in the measurement of exposure from mobile phones (or other hand-held transmitters), but also eminently suitable for radio radiation pattern testing.

SAM was defined as standard phantom allowing a conservative measure of the radio exposure of people of all origins and all ages. The ear region was been defined with reference points and planes to facilitate reproducible positioning of telecommunications devices.

SAM was originally developed as part of project SARSYS, a European Collaborative Research Programme under the EUREKA scheme. The SARSYS consortium members were MCL, SPEAG and the University of Gent.

To guide the specification of a realistic shape phantom, the anatomical shape and size were obtained from the data of a large anthropometric study of men and women of various ethnic origins, aged over 20 years, randomly selected among US Army personnel. The study was carried out in the late 1980s; its findings are considered to be still representative today's society. The dimensions of a 90th percentile male head were selected for the phantom.

The lines, arcs and circumferences that determine the shape of the SAM head were applied to a clay sculpture of a head and shoulder model. The sculpture was then used to produce a lightweight, fibreglass shell which was digitised and the three dimensional data stored as a CAD file. An outer shape was generated, incorporating a well defined shell thickness and outer ear in accordance with the shape of the model. The CAD file was translated to a physical model an accuracy of 0.1 mm using a computerised stereolithographic procedure.

CENELEC, IEC and IEEE have developed standard procedures for assessing exposures from mobile phones which specify the use of a SAM phantom. The Cellular Telecommunications & Internet Association (CTIA) has specified a phantom head, based on the SAM dataset, for the measurement of radiated RF Power and receiver performance.

MCL-T has now produced the next generation of SAM heads - solid heads that match the electrical properties of tissue over a wide frequency range and do not need to be filled with tissue-equivalent liquid.