Efficient Computation of Spatially-Discrete Traveling-Wave Modulated Structures

TL;DR

This paper introduces an efficient simulation method for spatially-discrete traveling-wave modulated structures by deriving an interpath relation that reduces computational complexity significantly.

Contribution

The authors derive a novel interpath relation that allows simulation of traveling-wave modulated structures using a single unit cell, simplifying and accelerating the process.

Findings

The interpath relation accurately predicts fields throughout space from a single unit cell.

The modified solver reduces computational resources by focusing on one time-modulated unit cell.

The method enables efficient simulation of complex and continuous traveling-wave structures.

Abstract

Traveling-wave modulation is a form of space-time modulation which has been shown to enable unique electromagnetic phenomena such as non-reciprocity, beam-steering, frequency conversion, and amplification. In practice, traveling-wave modulation is achieved by applying a staggered time-modulation signal to a spatially-discrete array of unit cells. Therefore, the capability to accurately simulate spatially-discrete traveling-wave modulated structures is critical to design. However, simulating these structures is challenging due to the complex space-time dependence of the constituent unit cells. In this paper, a field relation (referred to as the interpath relation) is derived for spatially-discrete traveling-wave modulated structures. The interpath relation reveals that the field within a single time-modulated unit cell (rather than an entire spatial period) is sufficient to determine the field solution throughout space. It will be shown that the interpath relation can be incorporated into existing periodic method of moments solvers simply by modifying the source basis functions. As a result, the computational domain is reduced from an entire spatial period to a single time-modulated unit cell, dramatically reducing the number of unknowns. In the context of traveling-wave modulation, this enables researchers to efficiently simulate both complex structures with patterned unit cells in addition to continuous structures with infinitesimal unit cells.