Real-Time Discrete Fractional Fourier Transform Using Metamaterial Coupled Lines Network

TL;DR

This paper introduces a passive metamaterial coupled lines network (MCLN) that performs real-time discrete fractional Fourier transforms at microwave frequencies, offering a compact and efficient solution for signal processing applications.

Contribution

The paper presents a novel MCLN design capable of performing arbitrary fractional order DFrFT in real-time, with experimental validation at microwave frequencies.

Findings

Successfully designed and implemented a 16x16 MCLN for DFrFT

Demonstrated real-time analog DFrFT performance

Scalable design applicable to millimeter and submillimeter waves

Abstract

Discrete Fractional Fourier Transforms (DFrFT) are universal mathematical tools in signal processing, communications and microwave sensing. Despite the excessive applications of DFrFT, implementation of corresponding fractional orders in the baseband signal often leads to bulky, power-hungry, and high-latency systems. In this paper, we present a passive metamaterial coupled lines network (MCLN) that performs the analog DFrFT in real-time at microwave frequencies. The proposed MCLN consists of M parallel microstrip transmission lines (TLs) in which adjacent TLs are loaded with interdigital capacitors to enhance the coupling level. We show that with proper design of the coupling coefficients between adjacent channels, the MCLN can perform an M-point DFrFT of an arbitrary fractional order that can be designed through the length of the network. In the context of real-time signal processing for realization of DFrFT, we design, model, simulate and implement a 16x16 MCLN and experimentally demonstrate the performance of the proposed structure. The proposed innovative approach is versatile and is capable to be used in various applications where DFrFT is an essential tool. The proposed design scheme based on MCLN is scalable across the frequency spectrum and can be applied to millimeter and submillimeter wave systems.