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Interpreting electric field distribution in metallic chamber

Posted 2024年9月29日 GMT-4 08:39 Electromagnetics, RF & Microwave Engineering, Results & Visualization Version 6.2 2 Replies

Sujeong Lee
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Hello. I'm simulating microwave furnace consists of waveguide, 2.45Ghz 3kw magnetron, metallic chamber.

I'm am troubling interpreting the result. According to my waveguide mode analysis, I found that microwave in the rectangular waveguide propagates with TE10 mode.(You can see the picture below)

But when I combined waveguide with metallic chamber, I could see that there are 2 hot spots in the microwave chamber and I don't understand why it happens.

I think that the result should show electric field concentrated on the middle.

  1. If you have any idea why it shows result like the picture I posted, I would appreciate your advice.

  2. If you have no idea why it happens, is there any recommendation for analysis tool that helps me to understand the result?

Thank you a lot.

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2 Replies Last Post 2024年9月29日 GMT-4 13:35
Edgar J. Kaiser Certified Consultant
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Posted: 2 months ago 2024年9月29日 GMT-4 10:57

The wavelength of the 2.45 GHz radiation is approximately 12 cm. The chamber is probably bigger and it has a number of modes with more than one maximum. It is even unlikely to see a mode with just one central maximum.

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
The wavelength of the 2.45 GHz radiation is approximately 12 cm. The chamber is probably bigger and it has a number of modes with more than one maximum. It is even unlikely to see a mode with just one central maximum.
Dave Greve
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Posted: 2 months ago 2024年9月29日 GMT-4 13:35

This is really more of a microwave engineering question.

In the usual microwave oven, the chamber is several wavelengths in size. So one way to think about it is that microwaves reflect from the walls and interfere. If there are enough paths (and maybe the entrance point is chosen carefully) then the energy density will be roughly uniform- often what we want.

In this case the chamber is only a few wavelengths in size. So seeing hot spots is not unexpected, as there are only a few ways that waves can reflect and interfere. If the thing to be heated is small it might make sense to choose a chamber with just ONE mode with energy concentrated in a single location.*

It may be easier to understand what is happening in THIS geometry if you make several plots of different components of the electric field (I think your plot is of the field magnitude).

  • Turns out I recently finished a simulation of heating a small sample in a 2.45 GHz waveguide. In this case the sample was placed roughly in the center and a movable short was adjusted to provide maximum heating.
This is really more of a microwave engineering question. In the usual microwave oven, the chamber is several wavelengths in size. So one way to think about it is that microwaves reflect from the walls and interfere. If there are enough paths (and maybe the entrance point is chosen carefully) then the energy density will be roughly uniform- often what we want. In this case the chamber is only a few wavelengths in size. So seeing hot spots is not unexpected, as there are only a few ways that waves can reflect and interfere. If the thing to be heated is small it might make sense to choose a chamber with just ONE mode with energy concentrated in a single location.* It may be easier to understand what is happening in THIS geometry if you make several plots of different components of the electric field (I think your plot is of the field magnitude). * Turns out I recently finished a simulation of heating a small sample in a 2.45 GHz waveguide. In this case the sample was placed roughly in the center and a movable short was adjusted to provide maximum heating.

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