# Application Gallery

The Application Gallery features COMSOL Multiphysics® tutorial and demo app files pertinent to the electrical, structural, acoustics, fluid, heat, and chemical disciplines. You can use these examples as a starting point for your own simulation work by downloading the tutorial model or demo app file and its accompanying instructions.

Search for tutorials and apps relevant to your area of expertise via the Quick Search feature. To download the MPH-files, log in or create a COMSOL Access account that is associated with a valid COMSOL license. Note that many of the examples featured here can also be accessed via the Application Libraries that are built into the COMSOL Multiphysics® software and available from the File menu.

### Substrate Integrated Waveguide Leaky Wave Antenna

Substrate Integrated Waveguides (SIW) can be used in antenna applications. Leaky waves from a slot array on the top surface of the SIW in this model generate a beam in a certain direction that can be steered by choosing a different operating frequency.

### Finding the Impedance of a Coaxial Cable

The coaxial cable (coax) is one of the most ubiquitous transmission line structures. It is composed of a central circular conductor, surrounded by an annular dielectric, and shielded by an outer conductor. This model computes the electric and magnetic field distribution inside of the coaxial cable, analyzes the impedance, and compares the result with the analytic solution.

### Second Harmonic Generation of a Gaussian Beam

Laser systems are an important application area in modern electronics. With nonlinear materials it is possible to generate harmonics that are a multiple of the frequency of the laser light. This model shows how a second harmonic generation can be set up as a transient wave simulation, using nonlinear material properties. A YAG (lambda=1.06 microm.) laser beam is focused on a nonlinear crystal, ...

### 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 the Port boundary conditions to feed a rectangular waveguide.

### Computing the Radar Cross Section of a Perfectly Conducting Sphere

A classic benchmark problem in computational electromagnetics is to solve for the radar cross section (RCS) of a sphere in free space illuminated by a plane wave. This model solves for the RCS of a metallic sphere that has a very high conductivity, which can be treated as a material with infinite conductivity. Results are compare to the analytic solution, and agreement is shown.

### MRI Birdcage Coil

Magnetic resonance imaging (MRI) systems generate a magnetic flux density (B-field) to create images. Providing a homogeneous field distribution within a birdcage coil is a key factor for improving the quality of the scanned data. A homogeneous magnetic field can be found through quadrature excitation, in combination with the appropriate number of lumped elements. In this model, the magnetic ...

### Connecting a 3D Electromagnetic Wave Model to an Electrical Circuit

A model built with the RF Module can be connected to an electrical circuit equivalent, if there is some structure outside of the model space that you wish to approximate as a circuit equivalent. In this model, the 3D model of a coaxial cable is connected to a voltage source, in series with a matched impedance, and sees a load, also of matched impedance.

### Notch Filter Using a Split Ring Resonator

A split ring resonator (SRR) has a band-stop frequency response that rejects a certain range of frequency. This type of SRR structure is popularly used as a resonator itself and can be combined periodically to build artificial meta-materials. In this model, a printed SRR on a dielectric substrate is coupled to a microstrip line. The entire circuit behaves as a notch (band-stop) filter, which ...

### Monopole Antenna Array

It is possible to shape the radiation pattern and steer the beam from an antenna array by controlling the relative phases and magnitudes of the input signal. This example shows how to design an active electronically scanned array (AESA) using arithmetic phase progression on each antenna element.

### Parameterized Circulator Geometry

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.

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