QOSM - Quasi Optical System Modelling

Description

QOSM (Quasi Optical System Modelling) is a simulation module developed at IMT Atlantique for modelling quasi-optical systems. This project is part of research conducted within the Microwave Department and the Lab-STICC laboratory.

Main Objective

The QOSM module was designed to simulate and model quasi-optical benches for material characterisation in millimetre and sub-millimetre frequency ranges. It enables the analysis of dielectric properties of materials through free-space measurements.

Key Features

Gaussian Beam Modelling

The system uses Gaussian beam expansion and tracking analysis combined with modal analysis. This approach enables modelling of electromagnetic wave propagation in quasi-optical systems.

S-Parameter Analysis

The module allows comparison of simulated reflection and transmission S-parameters with those measured using a 4-port vector network analyser. This functionality is essential for validating theoretical models against experimental measurements.

TRL Calibration

A Thru-Reflect-Line calibration is implemented to de-embed the simulated S-parameters of a dielectric slab located between two lens antennas, enabling precise extraction of material properties.

Project Architecture

The QOSM project is centralised in a single GitLab repository:

• qosm: Main project repository (https://gitlab.imt-atlantique.fr/quasi-optical-system-modelling/qosm)

The project groups all quasi-optical modelling functionalities in a unified structure.

Technologies Used

Based on research, the project likely uses:

• Gaussian beam propagation algorithms
• Modal analysis methods
• Scientific computing tools for electromagnetic simulation

Scientific Context

What is Quasi-Optics?

Quasi-optical systems are used in a domain where beam and component dimensions are several multiples of the wavelength. For example, at 263 GHz, the wavelength is 1.14 mm, and using a 12.7 mm aperture represents a factor 11 times larger than the wavelength.

Installation and Usage

Installation via PyPI

QOSM is available as a Python package on PyPI and can be easily installed using pip:

pip install qosm

Basic Usage

Graphical User Interface

Launch the QOSM GUI application:

python -m qosm

Python API

import qosm

# Example usage will depend on the specific API
# Please refer to the repository documentation for detailed examples

Note: For detailed usage examples and API documentation, please refer to the project repository or contact the development team at IMT Atlantique.

Associated Publications

Work on QOSM has led to scientific publications, notably in the International Journal of Microwave and Wireless Technologies in 2025, on "quasi-optical modelling of a millimetre- and submillimetre-wave free-space characterisation bench".

Development Team

The project is developed within:

• IMT Atlantique - Microwave Department
• Lab-STICC - PIM Team (Propagation and Microwave Imaging)

Main Contributors

• Gregory Gaudin
• Clément Henry
• Daniel Bourreau
• Alain Peden

Licence and Access

The project is hosted on IMT Atlantique's public GitLab instance:

• Main repository: https://gitlab.imt-atlantique.fr/quasi-optical-system-modelling/qosm
• Organisation: "Quasi Optical System Modelling" group on GitLab IMT Atlantique

The project is publicly accessible, allowing consultation of source code and documentation.