Multifrequency system model for multiport time-modulated scatterers

TL;DR

This paper introduces an advanced multiport S-parameters-based model for accurately predicting the multifrequency scattering behavior of time-modulated structures, including mutual coupling and structural scattering effects, validated through experiments.

Contribution

It extends existing models to account for multifrequency operation, structural scattering, and non-periodic configurations in time-modulated multiport structures.

Findings

Model accurately predicts multifrequency scattering behavior.

Validation confirms the model's practical applicability.

Enables improved design of reconfigurable and space-time modulated systems.

Abstract

Utilizing scatterers in communication engineering, such as reconfigurable intelligent surfaces (RISs) and backscatter systems, requires physically consistent models for accurate performance prediction. A multiport model, which also accounts for structural scattering, has been developed for non-periodic scatterers. However, many emerging systems operate at multiple frequencies or generate intermodulation harmonics, particularly when incorporating space-time modulation (STM) or dynamic load control. These functionalities demand advanced modeling approaches capable of capturing scattering behavior across several frequencies and directions simultaneously. This article extends a multiport S-parameters-based model for predicting the scattering properties of multifrequency operating structures. The model extends the applicability of convenient S-matrix models to time-modulated multiport structures. Unlike known approaches, this model incorporates structural scattering, mutual coupling, the possibility of non-digital modulation, and non-periodic configurations, enabling precise analysis and optimization for a broad range of communication and sensing systems. Validation against experimental results for a space-time modulated scattering structure demonstrates the accuracy and practical applicability of the proposed model.