Antenna-coupled bolometer with a micromachined-beam thermal link

We present the design of a novel bolometer intended for measurement of radiation within a waveguide. The thermal link in the bolometer is a low-thermal conductance micromachined beam. Power is coupled from an antenna to a resistive termination at the center of the beam. The optimization of the design for an astronomical measurement leads to an operating temperature of 0.48 K, accessible with a He-3 refrigerator, Measurements on the antenna absorber in a waveguide show an average absorption of 94% from 33 to 50 GHz. (C) 1997 American Institute of Physics.