Design guidelines for terahertz mixers and detectors

Twin-slot antennas and coplanar waveguide (CPW) are a popular choice for coupling signals to state of the art mixers and detectors at terahertz (THz) frequencies. Although these sensors show promising performance in terms of noise temperature, they usually also show a considerable downward shift in the centre frequency of their spectral response, especially when compared with calculations obtained with commonly used simplified models. In this paper, we describe an accurate and complete electromagnetic model of these detectors which represents a significant improvement over other published approaches. We present the procedure used to obtain a very good agreement between measurements and calculations at THz frequencies both in terms of centre frequency and bandwidth. The wide variety of measured and calculated data also demonstrates the effectiveness and reliability of the electromagnetic model in all the investigated frequency bands.