31 July 1998 Multibeam SIS mixer module for a focal plane array receiver
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Abstract
The integration of many receiver units into a receiver array is a common method of improvement of imaging systems. This approach, well known in the mm band for Schottky mixer arrays, has not so far been developed for Superconductor-Insulator- Superconductor (SIS) junction mixers, which give the best sensitivity in the short mm wave range and in the submm range. We demonstrate for the first time a practical low noise multibeam receiver module using SIS mixer technology. The module comprises three identical SIS mixers integrated with a common local oscillator, coupled through a three branch waveguide directional coupler. The multibeam module has been developed for a focal plane array receiver of the 30 meter radio telescope of the Institut de Radioastronomie Millimetrique (IRAM). Three such modules will be used in a 3 X 3 array operating near 230 GHz frequency. We discuss the requirements on the performance of the multibeam receiver module and compare it with a single beam receiver arrangement. After the presentation of a single mixer receiver operation the performance of the three mixer module is described. The basis for the integration of several SIS mixers with a common local oscillator source is given by the saturation of the SIS receiver noise dependence upon local oscillator power. The 1.3 mm SIS mixer block is built with a reduced height waveguide. The individual SIS junction area is 2.2 micrometer2 with a Josephson critical current density of about 3.6 KA/cm2. The minimum SSB receiver noise temperature at 230 GHz in a single beam receiver is as low as 50 K. In the module a common local oscillator power source is connected to the three mixers through a common three branch directional coupler. The performance of the three mixers is nearly identical across the 200 - 250 GHz band. The minimum DSB receiver noise temperature of 37 K is obtained simultaneously in all three channels around 230 GHz.
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Alexandre Karpov, J. Blondel, Matthew Carter, Bernard Lazareff, D. Billon-Pierron, K. H. Gundlach, "Multibeam SIS mixer module for a focal plane array receiver", Proc. SPIE 3357, Advanced Technology MMW, Radio, and Terahertz Telescopes, (31 July 1998); doi: 10.1117/12.317413; https://doi.org/10.1117/12.317413
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KEYWORDS
Receivers

Oscillators

Radio telescopes

Single sideband modulation

Double sideband modulation

Staring arrays

Waveguides

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