High-Performance Magnetoinductive Directional Filters

Artem Voronov,Oleksiy Sydoruk,Richard R A Syms

doi:10.3390/electronics11060845

Abstract

Multiport magnetoinductive (MI) devices with directional filter properties are presented. Design equations are developed and solved using wave analysis and dispersion theory, and it is shown that high-performance directional filters can be realised for use both in MI systems with complex, frequency-dependent impedance and in conventional systems with real impedance. Wave analysis is used to reduce the complexity of circuit equations. High-performance MI structures combining directional and infinite rejection filtering are demonstrated, as well as multiple-passband high-rejection filtering. A new method for improving filtering performance through multipath loss compensation is described. Methods for constructing tuneable devices using toroidal ferrite-cored transformers are proposed and demonstrated, and experimental results for tuneable MI directional filters are shown to agree with theoretical models. Limitations are explored, and power handling sufficient for HF RFID applications is demonstrated, despite the use of ferrite materials.

Highlights

Directional filters (DFs) are four-port directional couplers with frequency filtering capability [1–4]
Results and Discussion was developed to allow the demonstration of filter operation and extension to complex filters.we present experimental results for filters constructed for f 0 = 13.56 MHz to remove residual carrier from tag responses in high-frequency radio frequency identification (HF RFID)
Design rules have been established, and methods for calculating scattering parameters when filters are used in MI systems or conventional systems have been clarified

Summary

Introduction

Directional filters (DFs) are four-port directional couplers with frequency filtering capability [1–4]. Work on RF and microwave metamaterials showed that (in addition to other novel properties) periodic arrays of coupled metallic resonators allow the propagation of lattice waves including electroinductive (EI) [30–33] and magnetoinductive (MI) [34,35] waves. The latter have attracted considerably more attention for applications that depend on magnetic rather than electric fields. MI waveguides consist of arrays of magnetically coupled LC resonators They are band-limited and dispersive and have complex frequency-dependent impedance. Quasi-optical devices, such as matching networks, mirrors, resonators splitters, and couplers, can be synthesised [47–49], MI systems are still embryonic, and it is difficult to integrate other functionality, such as filtering

Methods

Results

Conclusion