We present a novel and compact frequency multiplier design for broad-band s
pectroscopy up to 1.38 THz, The multiplier generates harmonics of a fundame
ntal frequency between 110 and 240 GHz, The key element of the multiplier i
s a newly developed planar Schottky diode. Harmonic power generation is opt
imized with the aid of three tuning elements. The performance of the multip
lier was checked spectroscopically.