Isolation measurement between uplink and downlink antennas at low earth orbiting satellite ground station

The project “MOST” (Micro variability and Oscillations of Stars) is a Canadian micro satellite space telescope mission. The micro satellite carries a Rumak-Maksutov telescope with an aperture of 15cm. The size of the satellite is 65cm × 65cm × 30cm and the mass is about 65kg. The goals of the mission are to analyze the inner structure of stars, set a lower limit to the age of the universe and to search for Exoplanets. The project MOST consists of a Low Earth Orbiting (LEO) Satellite and three Ground Stations, one of them in Vienna [1]. The satellite link operates on 2GHz band. The separate antennas are used for uplink and downlink in order to achieve better downlink margin. The isolation measurement between uplink and downlink antennas is presented.

1. INTRODUCTION

The typical satellite communication system comprises of a ground segment, control segment and space segment. The link which transmits radio waves from the ground station to the satellite is called uplink. The satellite in turn transmits to the ground station by the downlink. The function of a ground station is to receive or transmit the information to the satellite in the most reliable manner while retaining the desired signal quality. There are two typical concepts of ground stations: single antenna system with the duplexer and double antenna system. At the single antenna concept, the separation of the transmission and reception is achieved by means of duplexer [2].