Optimization of reflector antennas in radio telescopes

Abstract

We present an analysis on the performance of Cassegrain reflector antennas. In our study, we have adopted the design parameters for the Cassegrain configuration used in the Atacama Large Millimeter Array (ALMA) project. We have adjusted the focal-length-to-diameter ratio f/D of the primary reflector to investigate the optimum performance of the antenna. In our study, signal frequency at the high edge of ALMA band 1, i.e. 45 GHz has been selected. The results obtained from the physical optics simulation show that the aperture efficiency of the antenna is at its optimum (i.e. 80.36%) when f/D ranges from 0.5 to 0.6. The radiation characteristics at this range of ratio are found to be similar. The radius of the secondary reflector and edge taper Te which correspond to the optimum aperture efficiencies ranges from 371 mm to 372 mm and 10.64 dB to 10.75 dB, respectively.