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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Dipole Antenna with a Quarter-Wave Coaxial Balun

An antenna balun blocks undesirable currents on the outside of a cable. A quarter-wave coaxial balun (1:1) is one of the easiest designs: it works as a transformer and makes the input impedance from the inner conductor to the outer conductor infinite. This model simulates an antenna prototype including a SMA Receptacle, an ABS enclosure and a quarter-wave coaxial balun. The frequency is tuned to ...

Dielectric Resonator Antenna

A dielectric resonator placed near a radiating element can be used to increase directivity and gain. Here, a block of quartz dielectric, with additional passive metallic antenna elements, is placed above a slot antenna. The fields in and around the antenna are solved for. The far field pattern and impedance is computed and improved performance is seen.

Antenna Decoupling Using An Electromagnetic Band Gap Meta-Material

An Electromagnetic Band Gap (EBG) structure can be used to increase the isolation between antennas close to each other. The decoupling effect is not only a function of frequency but also polarization and coupling-plane configuration. When designing an EBG structure, one needs to make sure to not apply an incorrect frequency and polarization, since this would increase the coupling between ...

Defining a Mapped Dielectric Distribution of a Metamaterial Lens

This example demonstrates how to set up a spatially varying dielectric distribution, such as might be engineered with a metamaterial. 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 ...

Log-Periodic Antenna for EMI/EMC Testing

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 ...

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.

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 ...

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.

TM Mode Microwave Plasma

This model shows how to simulate a TM mode microwave plasma by using the Doppler broadening parameter to smooth out the resonance zone, which occurs on the contour of critical electron density. A detailed explanation of the underlying physics of this model can be found in the blog entry "Application Note on Microwave Discharges".

Hexagonal Grating (RF)

A plane wave is incident on a reflecting hexagonal grating. The grating cell consists of a protruding semisphere. The scattering coefficients for the different diffraction orders are calculated for a few different wavelengths.