Phase-Shift Transmission Line Method for Permittivity Measurement and Its Potential in Sensor Applications

Abstract

This chapter offers a detailed insight into a dielectric characterization of the materials based on the phase-shift measurements of the transmission signal. The chapter will provide in-depth theoretical background of the phase-shift transmission line measurement in the microstrip architecture and determination of dielectric permittivity of design under test for several measurement configurations. Potential of the phase-shift method will be demonstrated through applications in the characterization of an unknown dielectric constant in multilayered structure, realization of the soil moisture sensor, and sensor for determination of the dielectric constant of a fluid in microfluidic channel. Moreover, specific techniques for increasing the phase shift based on the electromagnetic bandgap structure, the aperture in the ground plane and the left-handed effect will be presented. In the end, the realization of simple in-field detection device for determination of permittivity based on the phase-shift measurement will be demonstrated.

Novel Cost-Effective Microfluidic Chip Based on Hybrid Fabrication and Its Comprehensive Characterization

“…The effective permittivity of the proposed multi-layered configuration has been determined using a phase shift method, i.e., measurement of the phase delay of the sinusoidal signal that propagate along the transmission line [38,39]. For this purpose, the microstrip line was placed on the multi-layered substrate made of the combination of Ceram Tape and foil, as depicted in Figure 3.…”

“…The conductive layers, namely microstrip line and ground layer, have been realized using sticky aluminum tape. Based on the four set of measurements of two lines with different lengths and two thicknesses of the foil, the effective permittivity of the combination of the inhomogeneous dielectric substrate has been calculated using an equation for effective dielectric permittivity of the multi-layered substrate [38]. The phase and amplitude characteristics of the microstrip line has been determined using Agilent VNA E5071C in the frequency range between 500 MHz and 8.5 GHz.…”

An Ultrahigh Sensitive Microwave Microfluidic System for Fast and Continuous Measurements of Liquid Solution Concentrations

“…The relation between and can be illustrated using the so-called detection/sensing curve of the system. The phase shift introduced by the test channel ( ) is proportional (to an additive constant) to the length and the wavenumber of the microstrip line, as described below [ 25 ]: where is the frequency of microwave signals used in the system, is the length of the transmission line, and and are the effective permittivity and permeability of the medium in this transmission line, respectively. Any variation in the concentration of solution inside the microfluidic channel produces a change of and .…”

Microfluidic Sensor Based on Composite Left-Right Handed Transmission Line

“…The propagation constant and phase characteristics of the CLRH depend on the characteristics of the microstrip substrate (i.e., its dimensions and dielectric constant). Therefore, the change of the fluid in the microfluidic reservoir will influence the effective permittivity of the substrate and consequently the phase response [27]. For that reason, the central resonance of the LH band slightly shifts (Figure 6a), while the slope of the phase characteristics changes intensely (Figure 6b) when the properties of the fluid that flows through the microfluidic channel change.…”