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.

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Transmission Line Butler Matrix Beamforming Network

A Butler matrix is a passive beamforming feed network. It is a cost-effective feed network for phased array antennas because the circuit can be fabricated in the form of microstrip lines and is a viable solution for performing beam scanning without deploying expensive active devices. This example shows how to design such a circuit using the *Transmission Line* interface. The results show the ...

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 ...

Characteristic Parameters of a Coaxial Cable

Electrical cables, also called transmission lines, are used everywhere in the modern world to transmit both power and data. These cables carry electromagnetic energy, but instead of dealing with the full complexity of the electromagnetic fields, they are more commonly classified according to parameters such as capacitance, inductance, and impedance. In this model of a coaxial cable, we ...

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 ...

Biconical Antenna

A Biconical antenna is a type of wideband antenna with omni-directional radiation pattern in the H-plane similar to a dipole antenna. A coaxial feed is connected to the radiators using two 90 degree bent arms. The model shows that the biconical antenna works well in applications requiring an omnidirectional radiation pattern and wide bandwidth.

Radome with Double-layered Dielectric Lens

A radome minimizes losses and improves radiation characteristics of an antenna through its design. The structure can be optimized to minimize the transmission loss and also designed to improve radiation characteristics including antenna directivity and side lobes. Shown in the model is the surface current density on the patch antenna, the magnitude of the electric potential on the antenna's ...

Tunable Evanescent Mode Cavity Filter Using a Piezo Actuator

An evanescent mode cavity filter can be realized by adding a structure inside of the cavity. This structure changes the resonant frequency lower than the dominant mode of the unfilled cavity. A piezo actuator is used to control the size of a small air gap which provides the tunability of the resonant frequency.

Rat-Race Coupler

A 180° Ring Hybrid (Rat-Race Coupler) is a four-port network with 180° phase difference between two ports. It is cheaper to manufacture this type of microstrip line component compared to a wave guide 180° hybrid junction, so called magic-T. The objective of this model is to compute the S-parameters and to observe the matching, isolation, and coupling around the operating frequency.

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 ...

Anechoic Chamber Absorbing Electromagnetic Waves

An anechoic chamber is used to measure antenna characterization, electromagnetic interference (EMI), and electromagnetic compatibility (EMC). Within the chamber are absorbers that are configured with an array of pyramidal objects that steer the propagating incident field onto their neighboring absorbers. By absorbing electromagnetic waves inside the chamber and blocking incoming signals from ...