  A superconducting microstrip half-wavelength resonator is proposed as a
suitable band-pass filter for broadband moderate spectral resolution
spectroscopy for terahertz (THz) astronomy. The proposed filter geometry has a
free spectral range of an octave of bandwidth without introducing spurious
resonances, reaches a high coupling efficiency in the pass-band and shows very
high rejection in the stop-band to minimize reflections and cross-talk with
other filters. A spectrally sparse prototype filter-bank in the band 300-400
GHz has been developed employing these filters as well as an equivalent circuit
model to anticipate systematic errors. The fabricated chip has been
characterized in terms of frequency response, reporting an average peak
coupling efficiency of 27% with an average spectral resolution of 940.
