Behaviour of Orthogonal Wave Functions and Their Application to the Correction of Antenna Measurements
Authors: S F Gregson, A C Newell, G E Hindman
Mathematical Absorber Reflection Suppression (MARS) is a well-established, widely used measurement and postprocessing mode orthogonalization and filtering technique [1, 2] that has been extensively used to locate and then supress measurement errors arising from scattered fields when antenna testing is performed in echoic environments. Furthermore, it has been shown that this form of processing has reduced those uncertainties associated with bias leakage error, second order truncation effects, and mutual coupling (i.e. multiple reflections between the test antenna and the probe) leading to a worthwhile reduction in the overall range uncertainty budget. The success of MARS, and other mode orthogonalization and filtering strategies , is dependent upon the behaviour of the orthogonal vector wave functions (that are used to expand the electromagnetic fields) under an isometric translation of co-ordinate systems. This translation of origins is applied as part of the digital post-processing with the resulting mode orthogonalization being observed irrespective of whether plane, cylindrical, or spherical elemental vector mode bases are used. Within this paper and presentation, simulated and measured data will be used to demonstrate the power and flexibility of this technique when correcting measured data highlighting the specific behaviour of the various commonly used vector wave functions.