Simulation of the Frequency Characteristics of the Waveguide Structure of a Heterodyne Receiver with Separate Sidebands for the Range 211–275 GHz

The microwave properties of the components of the waveguide structure of a heterodyne receiver in the range 211–275 GHz with sideband separation based on a pair of superconductor–insulator–superconductor (SIS) tunnel junctions are described. The following elements of the waveguide structure have been studied: a hybrid four-port splitter, a directional coupler, a T-shaped splitter, and a waveguide absorber. S parameters for all elements are calculated. For the hybrid divider, the phase balance is additionally shown, which has deviations of less than 0.4 deg, and the amplitude balance is within 1 dB. The expected level of quality of band separation in a receiver with band separation when using the studied waveguide elements is analyzed, its value is more than –25 dB. Waveguide elements are designed taking into account that the block will be manufactured by precision milling; the minimum dimensions of the waveguide structure are limited by the diameter of the cutter used; in our case, 100 µm was chosen. All numerical calculations were performed by the finite interval method in the HFSS package.