Fundamentals of a 3-D "snowball" model for surface roughness power losses

Huray, Paul G.; Hall, S.; Pytel, S.G.; Oluwafemi, Femi; Meilitz, Richard; Hua, D.; Ye, Peng

doi:10.1109/memc.2020.9133247

Cited by 12 publications

(12 citation statements)

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“…Figure 10 showed that, regardless of RMS surface roughness of the transmission line and the operating frequency, if the modified roughness coefficient was less than or equal to 2.58, the electrical performance of the CPW transmission line degraded. Compared with the correlation factor proposed in [ 8 , 9 , 10 , 11 , 12 ], the modified roughness coefficient proposed in this paper could be a critical value to determine the effect of surface roughness and work frequency on the S parameters of the transmission line.…”

Section: Resultsmentioning

confidence: 99%

“…In 1949, Samuel Morgan researched the effect of surface roughness on conductor losses using a 2D surface distortion model [ 4 ]. Subsequently, several dedicated geometry models were proposed to describe the surface roughness of the conductor, such as the rectangular shape [ 5 ], triangular shape [ 4 , 6 ], hexagonal pyramid [ 7 ], hemisphere [ 8 , 9 ], stacked snowball [ 10 , 11 , 12 ], semi-cylindrical [ 13 ], certain arrangements of spheres [ 14 ], infinite periodic structures [ 15 ], and fractal geometries [ 16 , 17 , 18 , 19 , 20 ]. Although these geometry surface roughness models were easy to understand and simple, they were only suitable for some specific structures.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, analytical models were also used to study the surface roughness of the conductors, such as the gradient model [ 29 , 30 , 31 , 32 , 33 , 34 , 35 ], state-space formulation [ 33 ], Green’s function [ 36 , 37 , 38 ], fast Fourier transformation (FFT) [ 39 ], method of momentum (MoM) [ 40 ], small perturbation method [ 24 ], and Gaussian function from Campbell’s theorem [ 27 , 28 ]. Some other researchers added correction factors to change the smooth surface models to rough surface models [ 11 , 41 ]. This was a fast way to determine the surface roughness effect on high frequency devices.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Surface Roughness on the Electrical Performances of CPW Transmission Lines Used in Future Ultra-High Frequency Applications

Chen

Tian

2022

Micromachines

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The development of integrated circuits and packaging technology has led to smaller and smaller transmission line sizes and higher and higher operating frequencies up to nearly 100 GHz. However, the skinning depth of transmission lines due to eddy currents becomes smaller and smaller as the operating frequency of coplanar wave guide (CPW) transmission lines becomes higher and higher, while the reduction of device size makes the skinning depth consistent with the surface roughness of the device. In this paper, the concept of modified roughness coefficient was proposed based on the existing correlation factor. The concept of threshold modified roughness coefficient was proposed with a 20 dB reflection coefficient as the threshold value. The effect of surface roughness on transmission line transmission performance at frequencies above 100 GHz up to 1000 GHz was investigated. It was found that when the operating frequency of the signal was greater than the threshold roughness coefficient, the effect of surface roughness on the transmission line reflection coefficient should be considered. The modified roughness coefficient in this paper could quickly determine the effect of surface roughness on transmission line performance at different frequencies.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Surface Roughness on the Electrical Performances of CPW Transmission Lines Used in Future Ultra-High Frequency Applications

Chen

Tian

2022

Micromachines

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“…A conductor with a rough surface has additional losses, due to localized EM wave scattering from and power dissipation within microscopic surface defects [74]. Both become more significant at higher frequencies, as the dimensions of these defects become more significant when compared to the wavelength and classical skin depth, respectively.…”

Section: Surface Roughnessmentioning

confidence: 99%

Polymer-Based 3-D Printed 140 to 220 GHz Metal Waveguide Thru Lines, Twist and Filters

et al. 2023

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This paper demonstrates the current state-of-the-art in low-cost, low loss ruggedized polymer-based 3-D printed G-band (140 to 220 GHz) metal-pipe rectangular waveguide (MPRWG) components. From a unique and exhaustive up-to-date literature review, the main limitations for G-band split-block MPRWGs are identified as electromagnetic (EM) radiation leakage, assembly part alignment and manufacturing accuracy. To mitigate against leakage and misalignment, we investigate a 'trough-and-lid' split-block solution. This approach is successfully employed in proof-of-concept thru lines, and in the first polymer-based 3-D printed 90° twist and symmetrical diaphragm inductive iris-coupled bandpass filters (BPFs) operating above 110 GHz. An inexpensive desktop masked stereolithography apparatus 3-D printer and a commercial copper electroplating service are used. Surface roughness losses are calculated and applied to EM (re-)simulations, using two modifications of the Hemispherical model. The 7.4 mm thru line exhibits a measured average dissipative attenuation of only 12.7 dB/m, with rectangular-to-trapezoidal cross-sectional distortion being the main contributor to loss. The 90° twist exhibits commensurate measured performance to its commercial counterpart, despite the much lower manufacturing costs. A detailed time-domain reflectometry analysis of flange quality for the thru lines and 90° twists has also been included. Finally, a new systematic iris corner rounding compensation technique, to correct passband frequency down-shifting is applied to two BPFs. Here, the 175 GHz exemplar exhibits only 0.5% center frequency up-shifting. The trough-and-lid assembly is now a viable solution for new upper-mm-wave MPRWG components. With this technology becoming less expensive and more accurate, higher frequencies and/or more demanding specifications can be implemented.

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“…Since rough surfaces have more reflection spots than smooth surfaces, this effect might result in several diffusely distributed multipath components. [37][38][39][40] For every radiation angle (θ I ), the path length d, reflection angle θ 0 , and the total loss can be determined as 38…”

Section: Losses and Terahertz Channel Capacitymentioning

confidence: 99%

Analysis of path loss and channel capacity in quad element MIMO antenna for terahertz communication systems

Singh

Mahto

Kumar

et al. 2022

Circuit Theory & Apps

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A quad element multiple-input-multiple-output (MIMO) antenna with improved impedance bandwidth of 0.126 THz (0.198-0.324 THz) by using defected ground structure (DGS) is proposed for terahertz applications. The four elements are placed orthogonally to one another to reduce mutual coupling and envelope correlation coefficient (ECC). The maximum isolation of the proposed MIMO antenna is 34 dB at 0.290 THz frequency. The diversity performance characteristics of the proposed antenna are studied in terms of ECC, diversity gain (DG), mean effective gain (MEG), total active reflection coefficient (TARC), and isolation between the ports, and the obtained values are 0.05, 9.9, AE 3, À5, À10, respectively. Each antenna has a peak gain of 4.4 dBi with an average radiation efficiency of 92.5%. The proposed MIMO antenna is designed on a Rogers RO4003 substrate having a dielectric constant of 3.55, and a loss tangent of 0.0027 with a dimension of 700 Â 700 Â 55 μ m 3 .Further analyses of path loss in free space, atmospheric absorption, and roughness factor in indoor surfaces for THz communication are also studied. The designed MIMO antenna is suitable for high-speed short distance communication, video-rate imaging, biomedical imaging, sensing, and security scanning in the THz frequency band.

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Fundamentals of a 3-D "snowball" model for surface roughness power losses

Cited by 12 publications

References 1 publication

Effect of Surface Roughness on the Electrical Performances of CPW Transmission Lines Used in Future Ultra-High Frequency Applications

Effect of Surface Roughness on the Electrical Performances of CPW Transmission Lines Used in Future Ultra-High Frequency Applications

Polymer-Based 3-D Printed 140 to 220 GHz Metal Waveguide Thru Lines, Twist and Filters

Analysis of path loss and channel capacity in quad element MIMO antenna for terahertz communication systems

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