Use of Computational Techniques in Electromagnetics to Enhance the Accuracy and Efficiency of Antenna Pattern Measurements

The objective of this paper is to demonstrate that computational techniques in electromagnetics can be used very effectively to enhance the accuracy and efficiency of antenna pattern measurements. It is illustrated that this is carried out by using a simple dipole antenna used as a single probe to scan over the measurement plane in front of the near field of the antenna. Then using the measured induced voltages at the probe, computational techniques can be sued to find the equivalent currents on a plane in the near field of the antenna encompassing the device under test. Then once the equivalent currents are evaluated using computational techniques then the far field can be obtained using the free space Green's function. This is accomplished by moving a single probe over the measurement plane to generate enhanced accuracy in planar near field to far field transformation than over the classical Fourier based modal expansion methods. In this approach it appears that probe correction which is essential for the classical modal expansions is not required for this methodology. This method can provide accurate results for regions where the conventional modal expansions fail. This shall be illustrated using the planar near field to far field transformation techniques for the case when the source plane and the measurement planes are of equal size and for which it is well known that the conventional modal expansion techniques will fail. It shall be illustrated that instead of moving a single probe one can use an array of probes perhaps etched on a dielectric sheet and so simultaneously one can sample the fields in front of the antenna under test without having any moving components and thus enhancing the efficiency and accuracy of near field measurements. Even when using an array of probes in this methodology no probe correction is necessary. More details can be found in reference [1].