RF - Latest Discussions - COMSOL Forums

A problem in defining polarized current source

Fri, 21 Oct 2011 11:36:36 +0000

Hi,

I should have a line source current (strip) with y polarization (vertical polarization). I am using 2D simulation. I can add a line to my simulation and using boundary definition add a current, let's say 1A, but I do not have any control over the polarization. Can any one solve this issue or suggest a solution?

Thanks,
HN

Optical Fiber_3D Mode Analysis

Tue, 20 Sep 2011 06:23:57 +0000

Hi,

I'm studying the design for the optical waveguides. I wanted to obtain the results of 3D modal analysis of the optical fiber by using COMSOL (Model wizard - 3D - RF Module - EMW). And I selected the frequency domain in the study step. In the Geometry, the optical fiber was drawn, I set up the index of refraction of the core and clad in the Materials.
I made 2 Ports, and set those to the both side of the core of the optical fiber. And after that I formed the Mesh with Free Tetrahedral 1, fixed the frequency range from 3e14 to 4e14(the space is 0.1e14), and compute the Study.
(Referred to the h_bend_waveguide_3d of the model library, I made Parametric Sweep.)

Here, my question is as follows.

1. Why doesn't figure which the electric field shows normally come out properly?
2. The port seems to have to be set up in the optical fiber as the Coaxial,Why is the error generated if it does with the Coaxial? (tarnally, If it does with the Rectangular in the Type of Port, there is no error. Of course,but figure of the electric field came out wrong.)
3. Is the mistake that I selected to choose the frequency domain in the study step? In that case, Do I have to select the Boundary Mode Analysis or other thing?

The COMSOL seems to be so difficult in understanding. Please,a advice is asked I for.
(I attached the mph file which I made in the version 4.0a of the COMSOL)

Calculation of coupling losses

Thu, 11 Aug 2011 15:24:21 +0000

Hello,

I need a help in knowing the coupling losses and mode losses calculation in a hollow core photonic crystal fiber (HC-PCF) fiber when filleld with liquids(ethanol). I have attached the eigenvector solution for a single mode in PCF.

Heating inside microwave oven

Thu, 23 Dec 2010 21:27:09 +0000

Dear Sir
I'm trying to model the electromagnetic field distribution inside microwave oven used to heat a small specimen inside a container. I've survyed your example of heating a potato inside the cavity of microwave oven, but I couldn't understand making the mesh vector cubic, quadratic & linear using geometric multigrid. Also, about free mesh, why setting the maximum element size to 0.049/sqrt(dielectric constant)?
Does changing the location of th waveguide have an effect on the equation of the electric field you used? and if so, how can i formulate the suitable port equation for my model.

Thanks a lot,
Awaiting your kindly reply,
Iman Hassaballa

How to distinguish between inner and outer bounadry conditions.

Tue, 08 Jun 2010 10:24:43 +0000

Hello!

I have created a MATLAB script to set up 2D and 3D RF models.
To assign the correct boundary conditions I would need to be able to distinguish between inner and outer boundaries.

Is there any way to find out which index in fem.appl.bnd.ind corresponds to an inner and which to an outer boundary?

There should be a way, because Comsol in GUI mode is able to distinguish between the boundaries, however, I couldn't find a solution yet.

Thanks alot for your ideas!!!!!

Clemens

Multiple input ports in RF problems

Wed, 23 Sep 2009 06:36:07 +0000

Hello to everyone.

The RF module Users Guide, at page 72, says (Note at the top of the page) that it is possible to have more than an excited inport, with the drawback that S-parameters are not correctly computed.

On the contrary, COMSOL seems to not allow this: I need to excite a microwave cavity with two waveguides at the same time, but the program does not allow me to put a waveguide excitation on both ports.

Any suggestion?

Thnaks,
Roberto