Technical Note 1969 - 17 Pointing Accuracy of Lincoln Laboratory 28 - Foot Millimeter - Wave Antenna

Three experiments have provided a rough evaluation of the pointing errors of the 28-foot paraboloid and its mount. One examined the errors introduced by the pedestal, including the azimuth bearing, the second evaluated the pointing of an optical telescope attached to the backup structure, and the third showed that the departure between the telescope boresight and the millimeter-wave boresight is not a large fraction of a beamwidth. The experiments yielded estimates of base tilt, structural sag, elevation-axis skew, and collimation error. When allowance is made analytically for these defects, static pointing of the optical telescope at night has RMS errors of about 0.01 deg on each axis; this quantity is one-seventh of a 35-GHz beamwidth. Accepted for the Air Force Franklin C. Hudson Chief, Lincoln Laboratory Office