High temperature W-band complex permittivity measurements of thermally cycled ceramic-metal composites: AlN:Mo with 0.25 to 4.0 vol% Mo from 25 °C to 1000 °C in air

Cohick, Zane; Schaub, Samuel; Hoff, Brad W.; Dynys, Fred; Baros, Anthony E.; Telmer, Maxwell; Orozco, Haylie; Grudt, Rachael; Hayden, Steven C.; Rittersdorf, I. M.; Savrun, Ender

doi:10.1088/1361-6501/ac2ca6

Cited by 7 publications

(3 citation statements)

References 13 publications

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“…the waveguide method is widely used for broadband measurements of medium/high-loss materials in microwave and millimeter-wave bands due to its non-resonant character, high accuracy, and convenience. Such materials are widely used in vacuum electron tubes [5][6][7][8][9], accelerators [10], and power beaming [11]. Nevertheless, the measurement accuracy will decrease as frequency increases due to the imperfect sample preparation, especially for the materials with a high dielectric constant (real part of the complex permittivity) and loss tangent [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

An improved waveguide method for accurate complex permittivity measurement of medium/high-loss material

Wang,

Jiang,

Yao

et al. 2024

Meas. Sci. Technol.

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In this paper, we propose an improved method for accurately measuring medium/high-loss material permittivity to overcome the air gap problem in the conventional waveguide method.This method improves the sample fixture and has a high tolerance on the wide side air gap, which is a dominant factor affecting the accuracy of the conventional waveguide method.Meanwhile, the proposed method avoids the effects of tilting and displacement during sample assembly. In our study, a typical lossy material commonly used in vacuum tubes has been quantitatively analyzed in Ka-band. The simulation results show that the relative error of εr’ can be reduced from more than 10% to less than 1% compared with the conventional waveguide method with a 0.1mm wide side tolerance. The relative error of tanδ can be reduced from over 20% to below 6%. In addition, different lossy materials are discussed. The accuracy improvement was verified by measuring different BeO-TiO2 samples using conventional and improved methods.

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Section: Introductionmentioning

confidence: 99%

An improved waveguide method for accurate complex permittivity measurement of medium/high-loss material

Wang,

Jiang,

Yao

et al. 2024

Meas. Sci. Technol.

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“…Resonant methods are especially useful for measurements of low-loss materials at one or several discrete frequencies [2,3]. Nonresonant methods, such as coaxial line method, waveguide method, and free space method, can measure electromagnetic properties in a wide band [4,5].…”

Section: Introductionmentioning

confidence: 99%

Anisotropic complex permittivity measurement using a microstrip air line

Li,

2024

Meas. Sci. Technol.

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A microstrip air line system for measuring the complex permittivity of anisotropic materials in the band from 0.3 to 1 GHz is proposed. The multireflect-thru method is used to calibrate the measurement system in the whole band with a single microstrip air line without suffering from the limited space resolution of time-gating technique. During the measurement, the material under test (MUT) is placed both above and below the strip. With this deployment, the TEM mode propagates along the microstrip in the MUT. Therefore, it is possible to measure the anisotropic permittivity. Since a small portion of the electric field is parallel to the ground plane around two edges of the strip, the extracted property is not purely along one direction. To obtain higher accuracy, with the help of linear combination, the properties along two directions are disentangled by two measurements. For validation of the method, an isotropic material and an anisotropic material in the microstrip air line were simulated and their permittivities were extracted from simulation results. An anisotropic material polytetrafluoroethylene (PTFE) and two anisotropic materials, FR4 and honeycomb absorber, were measured. The results of PTFE show that there is a maximum relative error of 1.4% and 2.5% for the permittivity extracted from simulation and measurement, respectively. The validity and the accuracy of the system for measuring anisotropic materials are verified by the simulation and measurement results.

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“…Here, a sample material is placed in an oven with two openings, and the transmitted wave through the sample is used to understand its broadband dielectric properties. This method has been successfully scaled up to the W-band and 1200 °C by others like Hollinger et al [17] and has been further improved upon by Hilario et al [18] and Cohick et al [19]. Conversely, cavity-based methods allow for the employment of closed [13,20] and open cavities [21], but only the former has been successfully employed in the W-band.…”

mentioning

confidence: 99%

A wireless W-band 3D-printed temperature sensor operating beyond 1000 °C

Sánchez-Pastor,

Kadĕra,

Sakaki

et al. 2023

Preprint

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In addressing high-temperature sensing (above 500 °C), there is a gap in available chipless and wireless sensor systems operating near the high end of the microwave frequency range. This study introduces a novel dielectric wireless temperature sensor, leveraging high-Q cavities within a three-dimensional photonic crystal (PhC). To increase the readout range, a flattened Luneburg lens is added on top of the PhC structure. The sensor’s operating principle is based on detecting shifts in resonance frequency due to changes in the dielectric parameters of its conforming material over temperature. The sensor is 3D-printed using Lithography-based Ceramic Manufacturing in Alumina (Al2O3). Our empirical findings reveal that the sensor’s frequency-coded response, represented by two peaks at 83.5 GHz and 85.5 GHz, is clearly distinguishable at a distance of 50 cm and up to 1200 °C, the maximum capability of our furnace. Furthermore, we draw comparisons between the sensor’s performance and existing material characterization methods, particularly in estimating Al2O3’s dielectric permittivity and losses, with the latter showing a good agreement with literature values. Due to the employed materials, the sensor is suitable for millimeter-wave applications in dynamic, cluttered high-temperature scenarios.

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High temperature W-band complex permittivity measurements of thermally cycled ceramic-metal composites: AlN:Mo with 0.25 to 4.0 vol% Mo from 25 °C to 1000 °C in air

Cited by 7 publications

References 13 publications

An improved waveguide method for accurate complex permittivity measurement of medium/high-loss material

An improved waveguide method for accurate complex permittivity measurement of medium/high-loss material

Anisotropic complex permittivity measurement using a microstrip air line

A wireless W-band 3D-printed temperature sensor operating beyond 1000 °C

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