Higher Order Mode Absorbers for High Current SRF Applications

Eichhorn, Ralf; Conway, Joseph; Gruber, Terri; He, Yun; Hoffstaetter, Georg; Yu-lin, LI; Liepe, Matthias; O’Connell, Tim; Quigley, Peter; Sears, J.; Shemelin, Valery; Smith, Eric; Tigner, M.

doi:10.18429/jacow-srf2015-thba05

Cited by 1 publication

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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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