Berkeley Bolometer Group - Research


Posted on Feb 7, 2014

Bolometer systems would be simplified considerably if all components could be made photolithographically on a single substrate. We are developing a design for a single-substrate array with several frequency bands that incorporates a planar antenna for coupling to the telescope, transmission-line filters for separating and defining frequency bands,


Berkeley Bolometer Group - Research
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and lithographed bolometers. Antenna Coupling: Bolometer arrays are usually coupled to telescopes either by horns or by placing the absorbers directly in the focal plane. Another possible method is to use planar antennas. Planar antennas control the solid angle that is visible to the bolometer as with a horn, but are much easier to fabricate in large arrays. Our current design uses a double-slot dipole [filipovic97]. This antenna has many good features for use in bolometer arrays. It has a symmetric beam pattern and an impedance suitable for matching to microstrip transmission line. A dielectric lens in direct contact with the antenna is typically used, and the combination antenna/lens can be matched to the f/# of a telescope by adjusting the parameters of the lens. A dual polarization version of the double-slot dipole has been developed by Chattopadhyay and Zmuidzinas [chattopadhyay98]. Transmission-line Filters and RF Multiplexers: A planar antenna couples radiation from the telescope to a transmission line, for example, microstrip. Transmission-line elements can be used to separate the RF energy into multiple well defined frequency bands. There is a considerable literature on such devices from the electrical engineering community. We are investigating superconducting Nb microstrip resonant stub filters. The stubs are lambda in length and can be modeled as ``LC`` resonators. The in-band transmission of such filters can...




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