# 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.

### Sierpinski Fractal Monopole Antenna

A fractal is a mathematical form showing self-repeating patterns. By virtue of its geometrical properties, a fractal structure can generate multiple resonances in RF applications. This antenna model uses a 3rd order Sierpinski triangle and the calculated S-parameters shows good input matching at the higher order resonances.

### Defining a Mapped Dielectric Distribution of a Material (RF)

This example demonstrates how to set up a spatially varying dielectric distribution. Here, a convex lens shape is defined via a known deformation of a rectangular domain. The dielectric distribution is defined on the undeformed, original rectangular domain and is mapped onto the deformed shape of the lens. Although the lens shape defined here is convex, the dielectric distribution causes the ...

### A Low-Pass Filter Using Lumped Elements

Passive devices can be designed using lumped element features if both the operating frequency of the device and the insertion loss of lumped elements are low. This example simulates two types of lumped element filters that are similar to lumped ports, except that they are strictly passive and there are predefined choices for inductances and capacitance. First, a five-element maximally flat low ...

### Parabolic Reflector Antenna

A large reflector can be modeled easily with the 2D axisymmetric formulation. In this model, the radius of the reflector is greater than 20 wavelengths and the reflector is illuminated by an axial feed circular horn antenna. The simulated far-field shows a high-gain sharp beam pattern

### Log-Periodic Antenna

The shape of a log-periodic antenna resembles that of a Yagi-Uda antenna, but is composed of a coplanar array to achieve a wider bandwidth. It is also known as a wideband or frequency-independent antenna. All metallic parts are modeled using the perfect electric conductor (PEC) boundary conditions. The antenna is excited by a lumped port while a lumped element with a resistor is used to ...

### Branch-Line Coupler

A Branch Line Coupler (Quadrature 90° Hybrid) is a four-port network device with a 90° phase difference between two coupled ports. The device can be used for a single antenna Transmitter/Receiver system or an I/Q signal splitter/combiner. The objective of this model is to compute the S-parameters and to observe the matching, isolation, and coupling around the operating frequency.

### Time-Domain Modeling of Dispersive Drude-Lorentz Media (RF)

This tutorial shows how to solve the full time-dependent wave equation in dispersive media such as plasmas and semiconductors. The 2D TM in-plane wave model solves for the vector potential from the wave equation and for an auxiliary electric polarization density from an ordinary differential equation. The geometry consists of a single dispersive slab with a sub-wavelength slit in it. Periodic ...

### Double-Ridged Horn Antenna

A double-ridged horn antenna is popularly used in anechoic chambers to characterize an antenna under test (AUT), from S-band to Ku-band, due to its reliable performance in a wideband frequency range. This tutorial models a double-ridged horn antenna and computes the voltage standing wave ratio (VSWR), far-field radiation pattern, and antenna directivity. A lumped port is assigned on the ...

### Car Windshield Antenna Effect on a Cable Harness

Modern cars have rear-windshield FM antennas to play FM radio. The radiation emitted from an antenna induces an electric current on the outer surface of any cable harnesses in the car, which can have negative effects. This model uses the RF Module to compute the far-field radiation pattern of the antenna, by enclosing the car in perfectly matched layers separated by an air domain. The electric ...

### Thermal Drift in a Microwave Cavity Filter

Microwave filters are used to eliminate unwanted frequency components in the output from microwave transmitters. They are typically inserted between a power amplifier and an antenna. The amplifiers are nonlinear and produce harmonics that must be eliminated with filters that have a rather narrow passband. Due to high power loads but also possibly from harsh environmental conditions (such as a ...

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