Modeling the frequency characteristics of the waveguide structure of a heterodyne receiver with sideband division for the range 211...275 GHz

The microwave properties of the components of the waveguide structure of a heterodyne receiver in the 211...275 GHz range with sideband separation based on a pair of superconductor–insulator–superconductor (SIS) tunnel junctions are described. The following elements of the waveguide were studied structures: hybrid four-port splitter, directional coupler, T-shaped splitter body and waveguide absorber. S parameters were calculated for all elements. For hybrid divider additionally shows a phase balance with deviations of less than 0.4 degrees, and an amplitude balance within 1 dB. The expected level of quality of band separation in a band separation receiver using the studied waveguide elements is analyzed; its value is more than –25 dB. The waveguide elements are designed taking into account the fact that the block will be manufactured using 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 using the finite interval method in the HFSS package.