A beam splitter is used to split a beam of light in two. One way of making a splitter is to deposit a thin layer of metal between two glass prisms. The beam is slightly attenuated within the layer, and split into two paths. In this example, the thin metal layer is modeled using a transition boundary condition which reduces the memory requirements. Losses in the metal layer are also computed.
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".
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.
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.
It is possible to realize a narrowband bandpass filter using cascaded microstrip coupled lines. In this example, a design composed of cascaded microstrip lines, each approximately a half wave length in size at the resonant frequency, is analyzed. The model is solved for the S-parameters and a very narrow bandwidth is observed.
Low frequency devices can be designed using lumped element features if both the operating frequency of the device and the insertion loss are low. In this model, a 5-element maximally low-pass filter is simulated. The resulting S-parameter show the cutoff at the intended frequency.
A bird-cage coil is used in Magnetic Resonance Imaging (MRI) applications as a receiving antenna. This particular coil would sit around limbs and be used to scan a leg or arm. The COMSOL Multiphysics with RF Module model illustrates how thin sheets of metal can be modeled using impedance boundary conditions. It also illustrates the use of lumped ports to design simple RF circuit elements such ...
One way to generate circular polarization from a microstrip patch antenna is to truncate the patch radiator. This model is tuned around the GPS frequency range. The axial ratios are calculated to show the degree of circular polarization.
An evanescent-mode cavity filter is resonant at a frequency lower than its original fundamental mode frequency. Evanescent mode resonance can be realized by creating a discontinuity or reactance inside the cavity. The basic model was modified by the addition of a metal box at either end representing a housing. Inside a dielectric substrate and a microstrip line coupled into the cavity. The ...
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 ...