“ Microwave Iiolography of Deep Space Network Rrfi.hctor Antennas

The microwave antenna holography imaging technique has progressed considerably in recent years. This technique has been successfully used for the diagnosis, analysis, and performance improvement of most of the National Aeronautics and Space Administration (NASA)/Jet Propulsion 1,aboratory (JPL) Deep Space Network (DSN) large reflector antennas, especially at the shorter wavelengths, The JPL Microwave Antenna Holography System (MAHST) enables high resolution and high precision antenna imaging with a standard deviation of 100 microns. Panel setting/unbending screw adjustment is provided to an accuracy of 10-20 microns. In May of 1994, the MAHST was applied to the newly constructed 34-meter beamwaveguide (BWG) antenna (11 SS-24) in Goldstonc, California. The application of the MAHST provided the critical RF performance necessary to meet not only the project requirements and goals but to surpass them. A performance increase of 0.35 dB at X-band (8.45 GHz), ancl 4.9 d13 at Ka-band (32 GHz) was achieved relative to the theodolite set surface, resulting in peak efficiencies of 75.25% at Xband and 60.6% at Ka-band from cassegrain focus F1 (reference to the input of the LNA). The main reflector was set in one application to 0.25-nm~ rms, making DSS-24 the highest precision antenna in the NASA JPL-DSN. The precision of the 11 SS-24 antenna (diamcte]/rms) is 1.36x 10s, and its gain limit is at 95 GHz.