# 案例集锦

COMSOL Multiphysics 案例库模型来自广泛的应用领域，包括电气、机械、流体和化工等行业。您可以下载现成即可使用的模型，以及详细的建模步骤说明，作为您建模工作的起点。请使用“快速搜索”查找与您的专业领域相关的模型，并登录或创建一个与有效的 COMSOL 许可证相关联的 COMSOL Access 帐户，下载模型文件。

### Impedance Matching of a Lossy Ferrite 3-port Circulator

A lossy ferrite circulator at 3GHz is modeled. Geometrical design parameters are varied to match the impedance for minimal reflection of the fundamental TE10 rectangular waveguide mode.

### Frequency Selective Surface, Periodic Complementary Split Ring Resonators

Frequency selective surfaces (FSS) are periodic structures with a bandpass or a bandstop frequency response. This model shows that only signals around the center frequency can pass through the periodic complimentary split ring resonator layer.

### Modeling of an RF Coil

RF coils are important in numerous applications ranging from wireless technology to MRI scanning equipment. This introductory tutorial model demonstrates how to find the fundamental resonance frequency of an RF coil as well as how to perform a frequency sweep to extract the coil's Q-factor.

### Computing Q-Factors and Resonant Frequencies of Cavity Resonators

A classic benchmark example in computational electromagnetics is to find the resonant frequency and Q-factor of a cavity with lossy walls. Here, models of rectangular, cylindrical, and spherical cavities are shown to be in agreement with analytic solutions.

### Optical Scattering off of a Gold Nanosphere

This model demonstrates the calculation of the scattering of a plane wave of light off of a gold nanosphere. The scattering is computed for the optical frequency range, over which gold can be modeled as a material with negative complex-valued permittivity. The far-field pattern and the losses are computed.

### Modeling a Dipole Antenna

The dipole antenna is one of the most straightforward antenna configurations. It can be realized with two thin metallic rods that have a sinusoidal voltage difference applied between them. The length of the rods is chosen such that they are quarter wavelength elements at the operating frequency. Such an antenna has a well known torus-like radiation pattern.

### Absorbed Radiation (SAR) in the Human Brain

Scientists use the SAR (specific absorption rate) to determine the amount of radiation that human tissue absorbs. This measurement is especially important for mobile telephones, which radiate close to the brain. The model studies how a human head absorbs a radiated wave from an antenna and the temperature increase that the absorbed radiation causes. The increasing use of wireless equipment has ...

### Microstrip Patch Antenna

The microstrip patch antenna is used in a wide range of applications since it is easy to design and fabricate. The antenna is attractive due to its low-profile conformal design, relatively low cost and very narrow bandwidth. It is known that the antenna impedance will be higher than an accepted value if fed from the edge, and lower if fed from the center. Therefore, an optimum feed point ...

### Plasmonic Wire Grating

A plane wave is incident on a wire grating on a dielectric substrate. Coefficients for refraction, specular reflection, and first order diffraction are all computed as functions of the angle of incidence. The model is set up for one unit cell of the grating, flanked by Floquet boundary conditions describing the periodicity. As applied, this condition states that the solution on one side of the ...

### Coaxial to Waveguide Coupling

Feeding a waveguide from a coaxial cable is a straightforward way to achieve electromagnetic waves inside a waveguide. Due to its small size and circular shape, the cable contributes significantly to the overall size of the problem. It is therefore necessary to keep the cable as short as possible. This model shows how to use pairs and the Port boundary conditions to feed a rectangular ...

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