Caption for Antenna Efficiency Plot

This plot shows calculated aperture efficiencies for the inner 15m of the ATCA (and Mopra) antennas. It assumes that at low frequencies the efficiency is 60%. Two curves are shown, corresponding to 250 and 150 micron rms surfaces. The calculations are based on the well-known Ruze formula.

Holographic measurements at Mopra and the ATCA show the present surfaces to have inaccuracies close to 250 microns rms. The antenna specification leads us to expect that we can obtain 150 micron rms after adjustment. Mopra efficiency measurements at 3mm yield values close to those calculated, giving confidence that the plots are sensible starting points.

Peter Hall, 5 March 1996.

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