Reflection coefficient method for antenna radiation pattern measurements

The paper presents developments of reflection coefficient method for antenna radiation pattern retrieval. The reflection coefficient of the antenna under test (AUT) is measured with multitude of known reflective loads in front of the antenna aperture. The reflection coefficient depends on how the field reflected from the load couples to the antenna aperture field. The field propagation from the AUT to the load and correspondingly from the load to the AUT can be modeled with Fourier techniques. Antenna aperture field can be retrieved from the measured reflection coefficients with iterative methods. However, the used algorithms do not model multiple reflections between the AUT and reflective load. In this paper, we study the multiple reflections with simulated results of a pyramidal horn antenna at 30 GHz and discuss briefly the mitigation of their effects. Also, a comparison of two cost function in the optimization procedure and effects of noise in radiation pattern retrieval are presented.