Holographic measurements of the NASA-JPL Deep Space Network antennas

Microwave holography, as applied to reflector antennas, is a technique which utilizes the Fourier Transform relation between the complex far-field radiation pattern of an antenna and the complex aperture distribution. Resulting aperture phase and amplitude distribution data are used to precisely characterize various crucial performance parameters, including panel alignment, subreflector position, antenna aperture illumination, directivity at various frequencies, and gravity deformation effects. The holography technique provides a methodology for analysis, evaluation, and RF performance improvement of large reflector and beam waveguide antennas. Strong CW signals obtained from geostationary sources are used as far-field sources. Microwave holography has been one of the most economical techniques for increasing the performance of the large DSN antennas in terms of cost-to-performance ratio. This paper describes the application of the holography technique as applied at the NASA-JPL Deep Space Network (DSN) antennas with an emphasis on the 34-m beamwaveguide (BWG) subnet, successfully preparing them for operation at Ka-band (32 GHz). A table summarizing the holography historical data is also included. Recent results in which we aligned the panels of the three 34-m BWG antennas (DSS-24, DSS-25 and DSS-26) to an rms surface precision of 0.25 mm is described. The precision of these antennas (diameter/rms) is 1.36×10⁵ and their gain limit is at 95 GHz