The development of the next-generation 5G wireless networks depends critically on the engineering of optimized high-frequency devices, employing dielectric materials. This work presents a comprehensive broadband dielectric characterization of polymers, ceramics and glasses from 5 GHz until 115 GHz.Various measurement techniques including split-post, split cavity, open resonator and free-space transmission are utilized to obtain wideband spectra. The frequency-dependent permittivity and losstangent are analyzed to identify suitable candidate materials exhibiting minimal dispersion and loss in the 5G millimeter-wave bands. The characterization reveals almost constant permittivity and a loss tangent that increases linearly with the frequency

Lanagan, Michael

Perini, Steven

Rodriguez-Cano, Rocio

English

    Aalborg UniversitetDielectric Characterization of Materials at 5G mm-Wave FrequenciesRodriguez-Cano, Rocio; Perini, Steven; Lanagan, MichaelPublished in:18th edition of the European Conference on Antennas and Propagation (EuCAP)Creative Commons LicenseUnspecifiedPublication date:2024Document VersionEarly version, also known as pre-printLink to publication from Aalborg UniversityCitation for published version (APA):Rodriguez-Cano, R., Perini, S., & Lanagan, M. (in press). Dielectric Characterization of Materials at 5G mm-Wave Frequencies. In 18th edition of the European Conference on Antennas and Propagation (EuCAP) IEEE.General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            - Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            - You may not further distribute the material or use it for any profit-making activity or commercial gain            - You may freely distribute the URL identifying the publication in the public portal -Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Downloaded from vbn.aau.dk on: January 23, 2024Dielectric Characterization of Materials at 5Gmm-Wave FrequenciesRocio Rodriguez-Cano∗†, Steven Perini†, Michael T. Lanagan†∗Dept. of Electronic Systems, Aalborg University, Aalborg, Denmark, rrc@es.aau.dk†Dept. of Material Science and Engineering, Penn State University, State College, PA, USAAbstract—The development of the next-generation 5G wirelessnetworks depends critically on the engineering of optimized high-frequency devices, employing dielectric materials. This workpresents a comprehensive broadband dielectric characterizationof polymers, ceramics and glasses from 5 GHz until 115 GHz.Various measurement techniques including split-post, split cavity,open resonator and free-space transmission are utilized to obtainwideband spectra. The frequency-dependent permittivity and losstangent are analyzed to identify suitable candidate materialsexhibiting minimal dispersion and loss in the 5G millimeter-wavebands. The characterization reveals almost constant permittivityand a loss tangent that increases linearly with the frequency.Index Terms—characterization, ceramic, dielectric, glass, loss,material, measurements, substrate, 5G, 6G.I. INTRODUCTIONThe implementation of 5G millimeter-wave (mm-wave)wireless networks has required the redesign of RF front-endcomponents like antennas, filters, and amplifiers so they canoperate at higher frequencies than previous generations [1].These devices are usually fabricated using dielectric substratematerials and metal conductors, which need to be characterizedat the new frequency bands is essential.Materials with both low dielectric constants and low lossare desirable for 5G applications [2]. Lower dielectric con-stants enable faster signal propagation through the substrate,allowing for higher data rates and lower latency. Additionally,low loss tangents help compensate for the intrinsically higherattenuation present at mm-wave frequencies, ensuring accept-able propagation loss through devices [3], [4].However, the dielectric properties of materials exhibit fre-quency dependence arising from intrinsic relaxation mecha-nisms. These atomic-scale processes cause resonance peaksand dispersion effects that span the electromagnetic spectrum.In solid materials, dipolar relaxation of molecular dipoles tendsto occur in the MHz frequencies, while vibrational resonancesof lattice ions are found in the THz region [5], [6]. Thedielectric behavior in the GHz range relevant for 5G deviceslies in an intermediate region that may be influenced by thetails of the dipolar and ionic relaxations, around MHz and THzfrequencies, respectively. Therefore, accurate broadband char-acterization is crucial to fully capture the frequency variationsof dielectric properties arising from these underlying physicalprocesses. Measuring only the low-frequency response couldprovide an incomplete picture of a material’s suitability for5G applications. However, there are limited published studiescharacterizing the GHz dielectric properties of materials suitedfor 5G applications. While some work has measured insulatingmaterials for printed circuit board (PCB) laminates [7], somematerials until 35 GHz in [8], some representative materialsfrom 20 to 110 GHz in [9], and the characterization of silicatesuntil THz frequencies has been done by the authors [10],[11], comprehensive data on ceramics and polymers in the5G mmWave range is lacking. Bridging this knowledge gapwith broadband dielectric metrology is imperative to facilitatethe development of 5G-enabled technologies.In this paper, we provide the measurement results of manycommercial glasses, fused silica, quartz, some ceramics andpolymers.II. MEASUREMENT TECHNIQUESTo obtain wideband dielectric characterization, a range ofmeasurement techniques spanning different frequency bandsmust be employed. For dielectric characterization from 5 GHzto 115 GHz, the Materials Research Institute at Penn StateUniversity possesses the following measurement techniques,which are shown in Fig. 1:• Split-post dielectric resonator (SPDR) from QWED, op-erating at 5.1 GHz.• Split cavity or resonant mode dielectrometer (RMD-C,GDK Product Inc.), with a single frequency below 20GHz.• Fabry-Perot open resonator (from Damaskos, Inc.) canprovide measurement results between 15-67 GHz.• Material characterization kit (MCK, from SWISSto12)provides measurement results between 70-115 GHz.The resonant techniques (split-post, split cavity, and openresonator) can obtain more accurate loss measurements thanthe free-space transmission techniques (MCK) [12]. However,each technique has its own loss threshold. For this reason, notall frequency points could be measured for all the materials.Further explanation about the measurement techniques can befound in [10].III. RESULTSA wideband frequency characterization of the dielectricproperties of several glasses, fused silicas, crystalline materials(quartz, sapphire, alumina), ceramics and polymers is shownin Fig. 2 and Fig. 3. A flat response of the real part of thepermittivity can be seen in Fig. 2. Polymers are the dielectricswith the lowest permittivity, which goes between 2 and 3.(a) (b)(c) (d)Fig. 1. Characterization techniques employed. (a) Split-post dielectric res-onator (b) Split cavity. (c) Open resonator. (d) MCK from SWISSto12.The measured Rogers ceramics, RO3003 and RO4835, comeafter the polymers, with dielectric constants of 3 and 3.7,respectively. Fused silicas come next, with a permittivity of3.8, followed by quartz. The commercial glasses measuredrange between 4.4 and 8, depending on the percentage ofnetwork modifiers. The materials with higher permittivitymeasured are sapphire and alumina, both crystalline aluminumoxides, but with different crystal structure. Sapphire has ahexagonal crystal structure, while alumina has a cubic one,which leads to different properties.0 20 40 60 80 100Frequency [GHz]246810Dielectric constantSapphireQuartzFS- 518FS- JGS2FS- HFM002.B2FS- 7980BK7Borofloat 33Gorilla GlassAF45OA-10GWindow glassRogers RO3003Rogers RO4835AluminaTeflonHDPELDPEFig. 2. Dielectric constant of different materials as a function of frequency.FS stands for fused silica.The loss tangent is plotted in Fig. 3. The tendency is anincrement of one order of magnitude over 100 GHz. Crys-talline materials exhibit the lowest loss, due to their orderedinternal structure. They reach the minimum loss threshold ofthe measurement techniques available at lower frequencies.The lowest loss measurable by the MCK is 10−3, therefore it isnot possible to measure the crystalline materials at the highestpart of the spectrum. Fused silicas are the materials with lowerloss after crystalline materials, followed by polymers. Glassesare the materials with the highest loss.0 20 40 60 80 100Frequency [GHz]10-510-410-310-210-1Loss tangentSapphireQuartzFS- 518FS- JGS2FS- HFM002.B2FS- 7980BK7Borofloat 33Gorilla GlassAF45OA-10GWindow glassRogers RO3003Rogers RO4835AluminaTeflonHDPELDPEFig. 3. Frequency evolution of the loss tangent of different materials.IV. CONCLUSIONIn conclusion, this work has demonstrated broadband di-electric characterization of various materials classes over awide frequency range from 5 GHz to 115 GHz relevant to5G applications. The results revealed that of the materialscharacterized, crystalline substrates provided the lowest losson the order of 10−4, followed by fused silicas and certainpolymers with loss below 10−3. Ceramic materials displayedloss tangents generally less than 10−2, while glasses exhibitedthe highest losses but still below 10−1 at 100 GHz. Meanwhile,the dielectric constant was observed to be relatively constantover the full frequency span for most materials. These insightshighlight the need for broadband metrology and confirm crys-tals, fused silicas, and select polymers as promising candidatesubstrate materials for 5G antennas, packaging, and otherwireless components due to their stable and low-loss dielectricproperties.ACKNOWLEDGMENTThis work was supported in part by the National ScienceFoundation through the Center for Dielectrics and Piezo-electrics under Grant IIP-1841453 and Grant IIP-1841466, andin part by the VILLUM FONDEN under Grant 41389.REFERENCES[1] Y. Chen, L. Tian, and Y. Li, “A reconfigurable compact rf module for5g,” in 2019 International Conference on Microwave and MillimeterWave Technology (ICMMT), pp. 1–3, IEEE, 2019.[2] L. Cai, J. Wu, L. Lamberson, E. Streltsova, C. Daly, A. Zakharian,and N. F. Borrelli, “Glass for 5g applications,” Applied Physics Letters,vol. 119, no. 8, 2021.[3] L. Wang, C. Liu, S. Shen, M. Xu, and X. Liu, “Low dielectric constantpolymers for high speed communication network,” Advanced Industrialand Engineering Polymer Research, vol. 3, no. 4, pp. 138–148, 2020.[4] L. Wang, J. Yang, W. Cheng, J. Zou, and D. Zhao, “Progress on polymercomposites with low dielectric constant and low dielectric loss for high-frequency signal transmission,” Frontiers In Materials, vol. 8, p. 774843,2021.[5] S. O. Kasap, Electronic materials and Devices. McGraw-Hill New York,2006.[6] A. K. Jonscher, Dielectric relaxation in solids. Chelsea Dielectrics PressLtd., 1983.[7] M. Kouzai, T. Ogiwara, A. Nishikata, and K. Fukunaga, “Dielectricproperties of insulating materials for printed circuit boards at mm-waves,” in 2006 IEEE Conference on Electrical Insulation and DielectricPhenomena, pp. 198–201, 2006.[8] A. M. Nasr, A. Y. Nashashibi, and K. Sarabandi, “Ultrawidebandcharacterization of complex dielectric constant of planar materials for 5gapplications,” IEEE Transactions on Instrumentation and Measurement,vol. 70, pp. 1–11, 2021.[9] B. Salski, J. Cuper, T. Karpisz, P. Kopyt, and J. Krupka, “Complexpermittivity of common dielectrics in 20–110 ghz frequency rangemeasured with a fabry–pérot open resonator,” Applied Physics Letters,vol. 119, no. 5, 2021.[10] R. Rodriguez-Cano, S. E. Perini, B. M. Foley, and M. Lanagan,“Broadband characterization of silicate materials for potential 5g/6gapplications,” IEEE Transactions on Instrumentation and Measurement,vol. 72, pp. 1–8, 2023.[11] R. Rodriguez-Cano, M. Lanagan, S. Perini, X. Li, and V. Gopalan,“Broadband dielectric characterization of glasses and other silicates upto the thz frequencies,” in 2023 IEEE International Symposium onAntennas and Propagation and USNC-URSI Radio Science Meeting(USNC-URSI), pp. 287–288, 2023.[12] J. Krupka, “Frequency domain complex permittivity measurements atmicrowave frequencies,” Measurement Science and Technology, vol. 17,no. 6, p. R55, 2006.

Dielectric Characterization of Materials at 5G mm-Wave Frequencies

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Dielectric Characterization of Materials at 5G mm-Wave Frequencies

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