Dual-Band Band-Pass Filter with Fixed Low Band and Fluidically-Tunable High Band.

Eiyong Park,Daecheon Lim,Sungjoon Lim

doi:10.3390/s17081884

Abstract

In this work, we present a dual-band band-pass filter with fixed low-band resonant frequency and tunable high-band resonant frequency. The proposed filter consists of two split-ring resonators (SRRs) with a stub and microfluidic channels. The lower resonant frequency is determined by the length of the SRR alone, whereas the higher resonant frequency is determined by the lengths of the SRR and the stub. Using this characteristic, we fix the lower resonant frequency by fixing the SRR length and tune the higher resonant frequency by controlling the stub length by injecting liquid metal in the microfluidic channel. We fabricated the filter on a Duroid substrate. The microfluidic channel was made from polydimethylsiloxane (PDMS), and eutectic gallium–indium (EGaIn) was used as the liquid metal. This filter operates in two states—with, and without, the liquid metal. In the state without the liquid metal, the filter has resonant frequencies at 1.85 GHz and 3.06 GHz, with fractional bandwidths of 4.34% and 2.94%, respectively; and in the state with the liquid metal, it has resonant frequencies at 1.86 GHz and 2.98 GHz, with fractional bandwidths of 4.3% and 2.95%, respectively.

Highlights

The increasing number of multi-standard and multi-application telecommunication systems including cognitive radios [1], modern transceivers [2], anti-jamming communication systems [3], and radar systems [4], has led to the development of new tunable filter topologies [5,6]
The filter with eutectic gallium–indium (EGaIn) has the insertion loss of 2.5 dB at 2.98 GHz and a fractional bandwidth of 2.95%. In this graph, when EGaIn is injected into the microfluidic channel, the even-mode frequency is shifted by 0.11 GHz and the fractional bandwidth is slightly decreased
We proposed a dual-band band-pass filter (BPF) with fixed low-band resonant frequency and fluidically-tunable high-band frequency

Summary

Introduction

The increasing number of multi-standard and multi-application telecommunication systems including cognitive radios [1], modern transceivers [2], anti-jamming communication systems [3], and radar systems [4], has led to the development of new tunable filter topologies [5,6] Such system require microwave circuits and components that can control variety different frequency bands and bandwidths. We propose a dual band tunable bandpass filter using liquid metal. In work, thecan fundamental the filter employed thethis tunable band be used forstructure sensors toof detect liquid materials.is a dual-band band-pass filter (BPF). Performance microfluidic channels used as the paths for the liquid metal were made of polydimethylsiloxane of the proposed BPF is validated from both simulation and measurements. The performance of the proposed BPF is validated from both simulation and measurements

design of theresonant proposed

Simulated

Process

Findings

Conclusions