Use of low loss substrate for developing sub-millimeter-wave mixers

This paper presents the measurement of a sub-harmonic mixer working at 220 GHz built on a cyclic olefin copolymer (COC) substrate compared with the same design fabricated on Rogers Duroid 5880 substrate. Furthermore it is the first time COC substrate is used for sub-millimetre wave mixers implementation. Some of its main properties are the low losses at high frequencies, the direct gold sputtering and the robustness. The measured results show noise temperature values below 1000 K with low local oscillator, LO, power levels; i.e., 2.5 mW. On the contrary, the sub-harmonic mixer fabricated over Rogers substrate presents higher noise temperature values, around 1200 K.