Holographic Antenna Validation Measurements

Near-field holographic antenna measurements at millimeter and sub-millimeter wavelengths, at the highest ever frequencies (230, 345 & 682 GHz) have been used to characterize the 6 m antennas of the 8-element Submillimeter Array, the first interferometric aperture synthesis array to operate at submillimeter wavelengths, up to 690 GHz. The surfaces were measured and set to 10 um (best). Near-field measurements at multiple near-field ranges and multiple frequencies and comparison with celestial far-field measurements validate near-field corrections and illumination profiles. Gravitational deformations are characterized through measurements at multiple elevations.  Holographic measurements at 0.68 THz validate the optics design through illumination profile measurements.