# Model Gallery

The Model Gallery features COMSOL Multiphysics model files from a wide variety of application areas including the electrical, mechanical, fluid, and chemical disciplines. You can download ready-to-use models and step-by-step instructions for building the model, and use these as a starting point for your own modeling work. Use the Quick Search to find models relevant to your area of expertise, and login or create a COMSOL Access account that is associated with a valid COMSOL license to download the model files.

### 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 ...

### Microwave Cancer Therapy

Electromagnetic heating is ideally suited for modeling in COMSOL Multiphysics. This model shows the area of hyperthermic oncology but the modeling issues and techniques are generally applicable to any problem involving electromagnetic heating. The purpose of this model is to compute the radiation field and the Specific Absorption Rate (SAR) in liver tissue for a thin coaxial slot antenna used in ...

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