Simulating the radiation loss of superconducting submillimeter wave filters and transmission lines using Sonnet EM

TL;DR

This paper presents a stratification method for Sonnet EM that accurately simulates radiation loss in superconducting millimeter-submillimeter wave circuits, validated by measurements at 374.6 GHz.

Contribution

The authors develop a stratification approach in Sonnet EM to model radiation loss in superconducting circuits, enabling accurate simulations of radiative resonant behavior.

Findings

Sonnet EM simulation agrees well with measurements at 374.6 GHz.

Artificial lossy layers effectively absorb radiation in simulations.

The method allows modeling of radiation loss in superconducting millimeter-wave circuits.

Abstract

Superconducting resonators and transmission lines are fundamental building blocks of integrated circuits for millimeter-submillimeter astronomy. Accurate simulation of radiation loss from the circuit is crucial for the design of these circuits because radiation loss increases with frequency, and can thereby deteriorate the system performance. Here we show a stratification for a 2.5-dimensional method-of-moment simulator Sonnet EM that enables accurate simulations of the radiative resonant behavior of submillimeter-wave coplanar resonators and straight coplanar waveguides (CPWs). The Sonnet simulation agrees well with the measurement of the transmission through a coplanar resonant filter at 374.6 GHz. Our Sonnet stratification utilizes artificial lossy layers below the lossless substrate to absorb the radiation, and we use co-calibrated internal ports for de-embedding. With this type of stratification, Sonnet can be used to model superconducting millimeter-submillimeter wave circuits even when radiation loss is a potential concern.