Near field investigation of coupling between two horns

Multiple horn clusters used in satellite feeds exhibit interaction effects resulting in distorted far-field patterns and mutual coupling at the ports of the antenna structure. Known published work concentrates attention on the mutual impedance problem or on the far-field effects, while experimental results are sparse and the near-field effects have received little attention. This paper reports on an experimental study of the nearfield structure of two interacting horns and the results demonstrate the difference between a simulated simple superposition case and the actual field of two interacting horns. The effect of a non-energized horn in the presence of an active one is also presented. The results indicate a substantial resonance effect due to adjacent horn edges, acting as line radiators, when spaced half a wavelength apart.