Showing papers by "Thomas G. Phillips published in 1988"

A broad-band low-noise SIS receiver for submillimeter astronomy

Abstract: A quasi-optical heterodyne receiver using a Pb-alloy superconductor-insulator-superconductor (SIS) tunnel junction as the detector and a planar logarithmic spiral antenna for the RF coupling is described, and its performance is compared with the predicted performance of a theoretical model. Noise measurements were made in the laboratory at frequencies between 115 GHz and 761 GHz, yielding double-sideband noise temperatures ranging from 33 K to 1100 K. The receiver has also been used for astronomical spectroscopy on the Caltech Submillimeter Observatory (Mauna Kea, Hawaii) at 115, 230, 345, and 492 GHz. >

Techniques of Submillimeter Astronomy

Abstract: This review discusses the relative merits of direct and heterodyne techniques for detection in the submillimeter band. A variety of astronomical observing conditions is examined, including those for mountain-top and space telescopes. The spectral resolution (Δν/ν) of the observation is shown to be an important factor in the decision between direct and heterodyne techniques and this is examined for resolutions ranging from 10−1 to 10−7, relevant respectively to measurements on continuum objects and quiescent interstellar clouds. The conclusions reached can be summarized by the approximate statement that direct detection is preferable for resolutions worse than 10−3. Heterodyne detection is preferable for all better resolutions, longward of a wavelength of about 100 μ m. The most effective detection element for heterodyne receivers in the submillimeter band is the superconducting tunnel junction (SIS). The physics of this device is described and reasons given for its suitability. Some recent innovations in terms of materials, microcircuits and radiation coupling schemes are presented.

A broadband low noise SIS receiver for submillimeter astronomy

Abstract: A quasioptical heterodyne receiver is described that uses a PbInAu alloy superconductor-insulator-superconductor (SIS) tunnel junction as the detector and a planar logarithmic spiral antenna for the radiofrequency (RF) coupling. Noise measurements were made at frequencies between 115 GHz and 761 GHz, yielding double-sideband noise temperatures ranging from 33 K to 1100 K. >