scholarly journals Electromagnetic Topology Analysis to Coupling Wires Enclosed in Cavities with Apertures

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Ying Li ◽  
Jianshu Luo ◽  
Guyan Ni ◽  
Jiyuan Shi
Keyword(s):  
Analytic Solutions ◽  
Numerical Results ◽  
Coupling Theory ◽  
Cavity Model ◽  
Frequency Range ◽  
Topology Analysis ◽  
Resonant Frequencies ◽  
Load Response ◽  
Aperture Coupling ◽  
Coupling Current

We use both electromagnetic topology (EMT) and the Baum-Liu-Tesche (BLT) equation to analyze a cavity model with an aperture. More precisely, we combine the aperture coupling theory and EMT to study the issues of the electromagnetic field penetration through apertures into a cavity and the coupling to a two-wire transmission line in it. We employ the equivalence principle to establish the equivalent source on the aperture. Then, we obtain the semi analytic solutions of the load response of the two-wire line in the cavity based on the Baum-Liu-Tesche (BLT) equation. In addition, based on the Agrawal model, we give the coupling current distribution at two loads for a two-wire line in the cavity. Finally, we present some numerical results to demonstrate the semi-analytic approach of this paper. In fact, these numerical results on the electric field shielding (EFS) of a rectangular cavity with an aperture agree well with the experimental results in the literature. Furthermore, for a two-wire line in the cavity with an aperture the induced current peaks at loads are observed in the frequency range, some of which are associated with the resonance of the aperture, and others correspond to the resonant frequencies of the cavity.

scholarly journals A Weighted-Least-Squares Meshless Model for Non-Hydrostatic Shallow Water Waves

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3195
Author(s):  
Nan-Jing Wu ◽  
Yin-Ming Su ◽  
Shih-Chun Hsiao ◽  
Shin-Jye Liang ◽  
Tai-Wen Hsu
Keyword(s):  
Least Squares ◽  
Shallow Water ◽  
Water Waves ◽  
Dynamic Pressure ◽  
Weighted Least Squares ◽  
Shallow Water Equation ◽  
Analytic Solutions ◽  
Numerical Results ◽  
Benchmark Problems ◽  
Time Marching

In this paper, an explicit time marching procedure for solving the non-hydrostatic shallow water equation (SWE) problems is developed. The procedure includes a process of prediction and several iterations of correction. In these processes, it is essential to accurately calculate the spatial derives of the physical quantities such as the temporal water depth, the average velocities in the horizontal and vertical directions, and the dynamic pressure at the bottom. The weighted-least-squares (WLS) meshless method is employed to calculate these spatial derivatives. Though the non-hydrostatic shallow water equations are two dimensional, on the focus of presenting this new time marching approach, we just use one dimensional benchmark problems to validate and demonstrate the stability and accuracy of the present model. Good agreements are found in the comparing the present numerical results with analytic solutions, experiment data, or other numerical results.

Analysis of a circular microstrip antenna on isotropic or uniaxially anisotropic substrate using neurospectral approach

2013 ◽  
Vol 33 (1/2) ◽  
pp. 567-580 ◽  
Author(s):  
Sami Bedra ◽  
Siham Benkouda ◽  
Tarek Fortaki
Keyword(s):  
Resonant Frequency ◽  
Quality Factor ◽  
Microstrip Antenna ◽  
Numerical Results ◽  
Spectral Domain ◽  
Quality Factors ◽  
Resonant Frequencies ◽  
Content Type ◽  
Anisotropic Substrate ◽  
Circular Microstrip Antenna

Purpose – The paper aims to propose an artificial neural network (ANN) in conjunction with spectral domain formulation for fast and accurate determination of the resonant frequency and quality factor of circular microstrip antenna printed on isotropic or anisotropic substrate. This neurospectral approach reduces the problem complexity. Design/methodology/approach – The moment method implemented in the spectral domain provides good accuracy but its computational cost is high due to the evaluation of the slowly decaying integrals and the iterative nature of the solution process. The paper introduces the electromagnetic knowledge combined with ANN in the analysis of circular microstrip antenna on isotropic or uniaxially anisotropic substrate to reduce the complexity of the spectral approach and to minimize the CPU time necessary to obtain the numerical results. Findings – The resonant frequency results obtained from the neural model are in very good agreement with the experimental and theoretical results available in the literature. Finally, numerical results for the substrate anisotropy effect on the resonant frequency, quality factor and radiation pattern are also presented. Originality/value – The paper develops fast and accurate model based on ANN technique to calculate the resonant frequencies and quality factors of circular microstrip antennas. ANN is used to model the relationship between the parameters of the microstrip antenna and the resonant frequencies and quality factors obtained from the spectral domain approach. This relatively simple model allows designers to predict accurately the resonant frequencies and quality factors for a given design without having to develop or run the spectral method codes themselves. The main advantages of the method are: less computing time than the spectral model, results with accuracy equivalent to that of full-wave models and cost effectiveness, since the client can use a simple PC for implementation. Another advantage of the proposed ANN model is that it takes into account the uniaxial anisotropy in the substrate without increasing the network size. This is done by combining ANN with electromagnetic knowledge.

MULTIBAND CPW-FED SLOT ANTENNA FOR WLAN/WIMAX APPLICATIONS

2015 ◽  
Vol 77 (10) ◽  
Author(s):  
Igbafe Orikumhi ◽  
Mohamad Rijal Hamid ◽  
Ali Nyangwarimam Obadiah
Keyword(s):  
Radiation Pattern ◽  
Return Loss ◽  
Coplanar Waveguide ◽  
Ground Plane ◽  
Slot Antenna ◽  
Frequency Range ◽  
Resonant Frequencies ◽  
Good Agreement

A square slot antenna fed by a coplanar waveguide (CPW) is presented in this paper. The design consist of two pairs of “F” shaped planar strips placed within a square slotted ground. The strips are used to excite multiple resonant frequencies, the strips are connected to the ground plane by means of ideal switches. The proposed antenna has achieved multiple resonant frequencies of 2.4/5.2/5.8 GHz for WLAN and 3.5/5.5 for WiMAX applications. The measured results shows a good agreement with the simulated results in terms of return loss, radiation pattern and gain. The proposed antenna is designed for the frequency range of 2 GHz to 7 GHz which makes it suitable for Bluetooth, WLAN and WiMAX applications. 

Constant Temperature at the Surface of an Initially Uniform Temperature, Variable Conductivity Half Space

1971 ◽  
Vol 93 (1) ◽  
pp. 55-60 ◽  
Author(s):  
Leonard Y. Cooper
Keyword(s):  
Temperature Distribution ◽  
Half Space ◽  
Constant Temperature ◽  
Analytic Solutions ◽  
Numerical Results ◽  
Transient Temperature ◽  
Uniform Temperature ◽  
Transient Temperature Distribution ◽  
Temperature Variable ◽  
Variable Conductivity

The transient temperature distribution resulting from a constant and uniform temperature being imposed on the surface of an initially uniform temperature, variable conductivity half space is studied. Various solution expansion ideas are discussed. These are utilized in the solution of an example problem, and the resulting approximate analytic solutions representations are compared to exact numerical results. One of these approximations is found to be superior to the others, and, in fact, it is shown to yield useful results over a range of variables where the nonlinearities of the problem are significant.

Earthquake Response of Roof Shells

1997 ◽  
Vol 12 (3-4) ◽  
pp. 149-159 ◽  
Author(s):  
Haruo Kunieda
Keyword(s):  
Shear Stress ◽  
Analytic Solutions ◽  
Numerical Results ◽  
Earthquake Response ◽  
Plane Shear ◽  
Kobe Earthquake ◽  
Roof Shells

This paper provides numerical results of the intensity and distribution of response accelerations and stresses of spherical domes and cylindrical roof shells subjected to the Kobe earthquake, using mathematically analytic solutions. It is shown that stresses, especially, in-plane shear stress of cylindrical roof shells, become extremely large when they were subjected to earthquakes of such class as the NS-components of the Kobe earthquake.

scholarly journals Using additive technologies to create broadband antennas with fractal geometry

2021 ◽  
Vol 13 (4) ◽  
pp. 427-434
Author(s):  
Andrey V. Smirnov ◽  
◽  
Alexander S. Fionov ◽  
Ilia A. Gorbachev ◽  
Elizaveta S. Shamsutdinova ◽  
...  
Keyword(s):  
3D Printing ◽  
Frequency Dependence ◽  
Fractal Geometry ◽  
Additive Technologies ◽  
Copper Coating ◽  
Frequency Range ◽  
Resonant Frequencies ◽  
Printing Technology ◽  
Broadband Antennas ◽  
3D Printing Technology

The paper presents the results of a study of the frequency dependence of the S11 parameters of antenna samples with fractal geometry, created using 3D printing technology, followed by the deposition of a conductive copper coating by galvanization. It is shown that changing the dimension of the fractal at different iterations, shifting and dividing the resonant frequencies, it is possible to flexibly form the working bands of antennas in any frequency range and any width. The developed designs can be used to create broadband rectennas.

scholarly journals Эффекты амплитудно-зависимого внутреннего трения в низкочастотном стержневом резонаторе из отожженной поликристаллической меди

2021 ◽  
Vol 91 (9) ◽  
pp. 1305
Author(s):  
В.Е. Назаров ◽  
А.Б. Колпаков
Keyword(s):  
Low Frequency ◽  
Analytical Description ◽  
Copper Sample ◽  
Frequency Range ◽  
Effective Parameters ◽  
Resonant Frequencies ◽  
Longitudinal Modes ◽  
Hysteresis Nonlinearity ◽  
Annealed Copper ◽  
Experimental And Theoretical Studies

Experimental and theoretical studies of the effects of amplitude-dependent internal friction in a low-frequency rod resonator made of annealed polycrystalline copper are carried out. The results of measurements of nonlinear losses and the shift of resonant frequencies at the first three longitudinal modes of the resonator in the kilohertz frequency range from 2 to 11 kHz are presented. The analytical description of the observed effects is carried out in the framework of the rheological model and the equation of state of a microhomogeneous medium with saturation of hysteresis losses and relaxation of its visco-elastic defects. From the comparison of experimental and analytical results, the values of the effective parameters of the hysteresis nonlinearity of the annealed copper sample and their dependence on the frequency are determined.

scholarly journals Characteristic Mode Analysis Based X-Band Defected Dodecagonal Patch Antenna

2019 ◽  
Vol 9 (1) ◽  
pp. 3216-3220
Keyword(s):  
Microstrip Antenna ◽  
Return Loss ◽  
Mode Analysis ◽  
Center Frequency ◽  
Frequency Range ◽  
Characteristic Mode ◽  
Resonant Frequencies ◽  
Band Frequency ◽  
X Band ◽  
The Impact

A defected dodecagonal microstrip antenna fed through co-planar waveguide and operating in X-band frequency range(8-12 GHz) is proposed. Characteristic mode analysis is employed in examining the impact of defects on the resonant frequencies and return loss. Contrast in return loss for the suggested antenna with and without defects is dealt through Characteristic mode Analysis. Geometrical aspects of the proposed antenna are 40 mm × 35.5 mm × 0.1 mm. Subtrate material used in design is FR4 with a dielectric constant (εr ) = 4.4 and height (h) = 0.1m. CST Microwave Studio is used to simulate antenna parameters and Characteristic mode analysis. A return loss of -49.5dB at center frequency of 10.12GHz is observed with a fractional bandwidth of 47.6%. Gain of the antenna peaks at 4 dBi in the band of operation.

scholarly journals Dynamical Implications of Diffusive and Convective Cosmic ray Propagation in Galactic Halos

1991 ◽  
Vol 144 ◽  
pp. 373-376
Author(s):  
D. Breitschwerdt ◽  
J.F. Mckenzie ◽  
H.J. Völk
Keyword(s):  
Wave Field ◽  
Strong Coupling ◽  
Thermal Plasma ◽  
Cosmic Ray ◽  
Analytic Solutions ◽  
Present Knowledge ◽  
Numerical Results ◽  
Alfvén Waves ◽  
Galactic Halos ◽  
Galactic Wind

On the basis of our present knowledge about Cosmic Ray (CR) propagation, it is argued that galactic halos should mainly consist of two parts, namely a lower region, extending from the disk-halo interface to a few kpc, in which CR diffusion prevails and an upper region, where convection dominates. The upper part is the possible site of galactic wind formation due to the strong coupling of the CRs to the thermal plasma via (mainly outwards propagating) Alfvén waves as a mediator. In the lower halo and also in the disk, the gas will be effectively static, the wave field will be almost random in its direction (due to stochastic gas motions), and the CRs must diffuse through the gas to escape. We present a model that describes both the upper and the lower halo and briefly discuss simple analytic solutions for the diffusion and numerical results for the convection region.

scholarly journals A Passive Wireless Crack Sensor Based on Patch Antenna with Overlapping Sub-Patch

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4327 ◽  
Author(s):  
Songtao Xue ◽  
Zhuoran Yi ◽  
Liyu Xie ◽  
Guochun Wan ◽  
Tao Ding
Keyword(s):  
Patch Antenna ◽  
High Frequency ◽  
Crack Width ◽  
Patch Antennas ◽  
Cavity Model ◽  
Measuring Range ◽  
Resonant Frequencies ◽  
Frequency Shifts ◽  
Strain Transfer ◽  
High Frequency Structure Simulator

Monolithic patch antennas for deformation measurements are designed to be stressed. To avoid the issues of incomplete strain transfer ratio and insufficient bonding strength of stressed antennas, this paper presents a passive wireless crack sensor based on an unstressed patch antenna. The rectangular radiation patch of the proposed sensor is partially covered by a radiation sub-patch, and the overlapped length between them will induce the resonate frequency shift representing the crack width. First, the cavity model theory is adopted to show how the resonant frequencies of the crack sensor are related to the overlapped length between the patch antenna and the sub-patch. This phenomenon is further verified by numerical simulation using the Ansoft high-frequency structure simulator (HFSS), and results show a sensitivity of 120.24 MHz/mm on average within an effective measuring range of 1.5 mm. One prototype of proposed sensor was fabricated. The experiments validated that the resonant frequency shifts are linearly proportional to the applied crack width, and the resolution is suitable for crack width measuring.

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