2002 - Validation of Semi-Anechoic Chambers with Tuned Halfwave-Dipoles Working over a Wide Frequency Band
Alexander Kriz*, Wolfgang Müllner*, Jochen Riedelsheimer**, Friedrich-Wilhelm Trautnitz** 16th International Wroclaw Symposium and Exhibition on Electromagnetic Compatibility, June 25-28, 2002* ARC Seibersdorf research GmbH** Albatross Projects GmbH
In this paper the latest techniques for validation of anechoic chambers are described. The Short Dipole Site Validation Method (SDSV) is based on the use of the CISPR 16 dipole in an expanded, non-resonant frequency range. The SDSV idea is great as it combines advantages of the Site Reference method (direct comparison of two site attenuations, no antenna factors involved, quasi-swept frequency scan, fast, volumetric) with advantages of the tuned half-wave dipole method (numerically calculable, very accurate). We have compared site validations done according to the Site Reference Method to SDSV results. Thereby we encountered several disadvantages of this new SDSV procedure. Due to the high antenna factors below the resonance frequency a good dynamic range of the test receiver is required. Another problem is the amount of time needed for the measurements. A set of at least three dipole pairs is required to cover the frequency range from 30 MHz to 1 GHz instead of two broadband antennas. The antenna pattern of dipole and broadband antenna are different this leads to different results in the site validation. For chamber validation the performance of the chamber itself should be checked. Therefore the antenna system for the validation procedure must be calibrated under exactly the same setup conditions (including antenna mast, tripod and antenna cables) as used for site validation. In the numerical simulation of the SDSV reference these influences can not be considered. Finally there is no reason to prefer the SDSV method to the site reference method.