We study the direct response of a superconducting Nb hot-electron bolometer
mixer centered at 2.5 THz that incorporates an Au/SiO2/Al microstrip trans
mission line. The direct response is studied using a Fourier transform spec
trometer. We find a peak response at a frequency of 2.1 THz, which is 20% l
ower than predicted based on a model that neglects the inductance effect in
the microbridge. (C) 2001 American Institute of Physics.