# COMSOL Blog

## Intro Model: Studying the Signal Strength of RF Coils

##### Amelia Halliday | May 9, 2014

RF coil technology is ubiquitous throughout the world and serves as a major component of technologies, from medical equipment to wireless connectivity. It is important to ensure that the coils contained within these devices transmit information from a source to its destination properly.

### Computing the Impedance of a Corrugated Waveguide

##### Walter Frei | March 25, 2014

It is well-known that you can use the RF Module to compute the impedance of lossless transmission line structures, such as coaxial cables of uniform cross section. But did you know that you can also compute an effective impedance for waveguides with non-uniform cross section? Let’s find out how!

### Modeling a Branch Line Coupler

##### Fanny Littmarck | March 14, 2014

Branch line couplers, a type of 90-degree or quadrature hybrid coupler, are popular because they are simple to fabricate and easy to design. They are passive devices commonly used in single-antenna transmitter systems and I/Q signal splitters/combiners. Let’s look at the basics of how this type of coupler works and some of its important design aspects.

### Benchmark Model Results Agree with Fresnel Equations

##### Lexi Carver | March 12, 2014

Have you ever wondered why boaters wear polarized sunglasses? It’s because sunlight reflecting off the water is primarily polarized in one direction, and polarized sunglasses will block this component of the reflected light, thus reducing glare. To understand why this is, we can use COMSOL software. This example solves the governing Maxwell’s equations using the RF Module or Wave Optics Module to simulate light incident at an angle upon a dielectric medium, and the solution shows agreement with analytic solutions.

### Modeling Electromagnetic Waves and Periodic Structures

##### Walter Frei | January 17, 2014

We often want to model an electromagnetic wave (light, microwaves) incident upon periodic structures, such as diffraction gratings, metamaterials, or frequency selective surfaces. This can be done using the RF or Wave Optics modules from the COMSOL product suite. Both modules provide Floquet periodic boundary conditions and periodic ports and compute the reflected and transmitted diffraction orders as a function of incident angles and wavelength. This blog post introduces the concepts behind this type of analysis and walks through the […]

### The Linac-MR Project: Tumor Tracking and Treatment

##### Alexandra Foley | December 30, 2013

Not too long ago, my colleague Jennifer wrote a blog post about the Cross Cancer Institute, and the research being conducted there into the design of a new device for treating cancerous tumors. The device, known as the Linac-MR, is revolutionary due to its ability to both image and treat cancer cells simultaneously — a capability that had previously been regarded as near impossible due to the conflicting physics interactions involved. Such a device would allow for extremely precise radiation […]

### Research on Microwave Heating and Chemical Applications

##### Fanny Littmarck | November 8, 2013

There were many interesting posters at this year’s COMSOL Conference in Boston. A couple that caught my eye involved microwave heating and chemical applications. One of them showcases the use of microwave irradiation to speed up chemical reactions. Another — one of the recipients of the Best Poster award — used simulations to optimize their microreactor design with respect to microwave propagation.

### Wilkinson Power Divider Simulation

##### Alexandra Foley | October 11, 2013

A Wilkinson power divider is a common three-port power splitter circuit that is used to split an input signal into two equal output signals, or to combine two signals into one. Unlike resistive or T-junction power dividers, a Wilkinson power divider allows for nearly complete isolation between the two ports and adds no resistive losses to the power split. Because of these characteristics, a Wilkinson divider is widely used in radio communication systems due to its ability to prevent crosstalk […]

### Spiral Resonator Filter Design Analysis

##### Fanny Littmarck | September 30, 2013

Wireless systems are growing increasingly thinner and more advanced. In order to keep this trend going, engineers must consider how to optimize the designs of the components that make up data transmission systems. One such component is the spiral resonator, which allows the system to communicate properly by filtering out unwanted frequencies and letting the appropriate ones through. Spiral resonator filter design can be analyzed and optimized using simulation software, as seen in a recent story from AltaSim Technologies.

### Perfect Imaging, From Theory to Reality via Simulations

##### Valerio Marra | September 27, 2013

Perfect imaging refers to the idea of producing images with details below the diffraction limit, where even the smallest elements can be resolved to unlimited sharpness regardless of the wavelength of light being used. While just a theory 150 years ago, research has brought us closer to reality over the years. Now, by way of simulation, researchers at Cedint Polytechnic University of Madrid in Spain are taking it one step further.