New Formula for the Reflection Coefficient of an Open-Ended Rectangular Waveguide With or Without an Infinite Flange

Kim, Jong‐Heon; Enkhbayar, Bayanmunkh; Bang, Jaehoon; Ahn, Bierng-Chearl; Cha, and Eun-Jong

doi:10.2528/pierm10033104

Cited by 10 publications

(4 citation statements)

References 16 publications

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“…Another huge advantage is that, similar to a resonant cavity, in the two-port measurement technique, the dielectric properties of the sample can be extracted by simple ‘relative’ measurement between air and sample . This allows us to avoid solving a complicated inverse problem (that is, calculating dielectric properties from the measured admittance) and reduce the requirement of the vector network analyzer and calibration procedure [ 59 , 60 , 61 ]. In other words, we can simply utilize a low-cost scalar network analyzer in extracting complex permittivity, so it is possible to design a miniaturized portable diagnostic system around the resonator.…”

Section: Probe Design and Characterizationmentioning

confidence: 99%

Cervical Tissue Hydration Level Monitoring by a Resonant Microwave Coaxial Probe

Choi

Barker

Abduljabar

et al. 2022

Sensors

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Cervical tissue hydration level is one of the most important parameters to monitor in the early diagnosis of preterm birth. Electrical-impedance-spectroscopy-based techniques are often used, but they suffer from limited accuracy. Open microwave coaxial probes have been widely used as a broadband dielectric characterization technique for human tissue samples due to their versatility, but with limited accuracy due to their nonresonant nature. In this work, a resonant microwave open coaxial probe with multiple harmonic resonances is proposed as a sensing platform for tissue-hydration-level monitoring. The mechanical design was analyzed and verified by finite-element full 3D electromagnetic simulation and experiments. Dominant sources of errors and the ways to mitigate them were discussed. In vitro experiments were carried out on human cervix samples to verify the precision and accuracy by comparing the results to a commercial skin-hydration sensor. The proposed sensor shows mean fractional frequency shift of (3.3 ± 0.3) × 10−4 per unit % over the entire data. This translates into an absolute frequency shift (ΔfN) of 252 ± 23 kHz/%, 455 ± 41 kHz/%, and 647 ± 57 kHz/% at second, fourth, and sixth harmonic resonance, respectively.

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Section: Probe Design and Characterizationmentioning

confidence: 99%

Cervical Tissue Hydration Level Monitoring by a Resonant Microwave Coaxial Probe

Choi

Barker

Abduljabar

et al. 2022

Sensors

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“…In a standard rectangular waveguide ranging from the largest WR2300 (584.2 × 282.1 mm 2 ; 0.32−0.49 GHz) to the smallest WR1(0.254 × 0.127 mm 2 ; 750−1100 GHz), b/a and t/a range from 0.406 to 0.512 and from 0.0081 to 0.467, respectively. The maximum reflection is 0.313 (−10.1 dB) for b/a = 0.406 and 0.225 (−13.0 dB) for b/a = 0.512 [9].…”

Section: Introductionmentioning

confidence: 97%

“…Since the first experiment in 1900 by Flemming [1] and the first scientific theory in 1938 [2], the rectangular waveguide open-end radiator, as one of the canonical radiating elements, has been used in a wide range of applications, including near-field antenna measurement [3][4][5][6][7][8][9], dielectric material characterization [10,11], electric field measurement [12,13], array antennas [14][15][16], electric field probe calibration [17], feeding a reflector antenna [18], non-destructive testing [19][20][21], imaging sensors [22] and the excitation of various radiating elements [23][24][25][26]. A comprehensive review of various open-ended waveguides has been presented in [27].…”

Section: Introductionmentioning

confidence: 99%

A New Technique for Broadband Matching of Open-Ended Rectangular Waveguide Radiator

Heo,

Xu,

Altanzaya

et al. 2023

Sensors

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The maximum reflection at an open end of a standard rectangular waveguide is about −10 dB in its operating frequency range. It is often used without matching. For critical applications, it is desirable to further reduce the reflection coefficient. In this paper, a new technique is presented for the broadband impedance matching of an open-ended rectangular waveguide. The proposed technique employs three thin capacitive matching elements placed at proper intervals via a low-loss dielectric material. The capacitance of, and distance between, the matching elements are optimized for broadband impedance matching using a simulation tool. Based on the proposed technique, two design examples are presented for the matching of a WR75 waveguide radiator. A reflection coefficient of less than −16 dB and −20 dB has been achieved over a ratio bandwidth of 2.13:1 and 1.62:1, respectively.

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“…Then, the measured S 11a_sample was converted to normalized admittance, Y/ Y o parameter by a formula: Y/Y o =( 1− S 11a_sample )/(1 + S 11a_sample ). The SOO calibration techniques were validated by comparing normalized admittance, Y/Y o with the literature data [15][16][17][18][19][20][21][22] as shown in Figure 14. The real part, Re(Y/Y o ), and the imaginary part, Im(Y/Y o ), of admittance results were found to be in good agreement with literature data over the operational range of frequencies.…”

Section: Short-offset-offset Short (Soo) Standard Calibrationsmentioning

confidence: 99%

Materials Characterization Using Microwave Waveguide System

You¹

2017

Microwave Systems and Applications

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This chapter reviews the application and characterization of material that uses the microwave waveguide systems. For macroscopic characterization, three properties of the material are often tested: complex permittivity, complex permeability and conductivity. Based on the experimental setup and sub-principle of measurements, microwave measurement techniques can be categorized into either resonant technique or nonresonant technique. In this chapter, calibration procedures for non-resonant technique are described.The aperture of open-ended coaxial waveguide has been calibrated using Open-Short-Load procedures. On the other hand, the apertures of rectangular waveguides have been calibrated by using Short-Offset-Offset Short procedures and Through-ReflectLine calibration kits. Besides, the extraction process of complex permittivity and complex permeability of the material which use the waveguide systems is discussed. For one-port measurement, direct and inverse solutions have been utilized to derive complex permittivity and complex permeability from measured reflection coefficient. For two-port measurement, in general, the material filled in the waveguide has been conventional practice to measure the reflection coefficient and the transmission coefficient by using NicholsonRoss-Weir (NRW) routines and convert these measurements to relative permittivity, ε r and relative permeability, μ r . In addition, this chapter also presents the calculation of dielectric properties based on the difference in the phase shifts for the measured transmission coefficients between the air and the material.

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New Formula for the Reflection Coefficient of an Open-Ended Rectangular Waveguide With or Without an Infinite Flange

Cited by 10 publications

References 16 publications

Cervical Tissue Hydration Level Monitoring by a Resonant Microwave Coaxial Probe

Cervical Tissue Hydration Level Monitoring by a Resonant Microwave Coaxial Probe

A New Technique for Broadband Matching of Open-Ended Rectangular Waveguide Radiator

Materials Characterization Using Microwave Waveguide System

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