In this paper, we present an analysis on the performance of the three most commonly used paraboloidal reflector antennas in radio telescopes – i.e. the prime focus, Cassegrain, and Gregorian antennas. In our study, we have adopted the design parameters for the Cassegrain configuration used in the Atacama Large Millimeter Array (ALMA) project. The parameters are subsequently re-calculated so as to meet the design requirement of the Gregorian and prime focus configurations. The simulation results obtained from GRASP reveal that the prime focus configuration produces the lowest side lobes and the highest main lobe level. Such configuration, however, has the disadvantage of being highly susceptible to thermal ground noise radiation. The radiation characteristics produced by both the Cassegrain and Gregorian configurations are very close to each other. Indeed, the results show that there is no significant advantage between the two designs. Hence, we can conclude that both configurations are comparable in the application of radio telescopes.
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