Mathematical gain models of large-aperture Earth station antennas for Space Research Service

Compatibility studies between Space Research Service (SRS) earth stations and high-density fixed systems are being conducted in the 31.8-32.3 GHz and 37-38 GHz bands. One of the key parameters in determining the level of interference that may occur at SRS earth stations is the antenna pattern to be used in the calculations. There are a number of antenna pattern models proposed in the literature and in various International Telecommunication Union (ITU) recommendations. In this paper, we propose and present a new gain model representing a peak envelope of the class of large aperture antennas currently in use at the SRS earth stations. This model takes into account the effect of surface tolerance on gain distribution in the main beam and at side-lobes. It includes aperture efficiency in away affecting both the peak and the side-lobe regions. It is demonstrated to have properties superior to the existing models in many respects. We also propose the use of the integrated average gain value as a validity check in evaluating the general accuracy of any model compared to an actual antenna pattern. An "average gain" model is also proposed to allow more accurate estimation of aggregate interference of a large number of distributed interfering sources. Many examples and plots are provided to clarify the concepts and compare and validate the proposed models.