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Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

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patch antennas RF module strange issue

Posted 2014年7月31日 GMT-4 19:11 RF & Microwave Engineering Version 4.3b 3 Replies

Farrukh Mateen
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Hi

I am following the patch antenna example given in the model library in the 4.3b comsol. I have also looked up other patch antenna example models. But the problem I have is that in all of them the patch antenna is modeled as an infinitely thin layer on top of the substrate. The top surface of the patch and the bottom surface of the substrate are both made PEC. Then through a lumped port the antenna is excited.

1. It works perfectly however I need to ask that the materials of the substrate and the patch are defined to be the same. I don't understand why this needs to be. Since if I need to simulate a copper patch antenna on a silicon (substrate) lets say then this method that has been explained in the model examples doesn't work. And I have tried it as well with everything remaining the same if I try to change the material of the patch the antenna doesn't transmit at all.

2. Also if I try to give the patch antenna a certain thickness (very small though say 0.5microns) and put it on top of the substrate (which is about 5 microns thick) and assign the top and bottom surface of the patch as PEC and the bottom surface of the substrate as PEC then also the antenna doesn't work. I have tried this both with the patch and antenna having the same material and different materials.

I just dont get this. I know it may be something small but would appreciate any help or ideas.

3 Replies Last Post 2014年8月3日 GMT-4 11:36
Farrukh Mateen
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Posted: 1 decade ago 2014年8月1日 GMT-4 10:00
guys would appreciate any response. Thanks
guys would appreciate any response. Thanks
Robert Koslover Certified Consultant
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Posted: 1 decade ago 2014年8月2日 GMT-4 17:43
You should be able to model a finite thickness patch. Instead of modeling the interior of the patch, subtract that volume from the overall problem volume, which will cause its surfaces to default to PEC. Then consider applying an impedance boundary condition to the patch, if you care about resistive losses there.
You should be able to model a finite thickness patch. Instead of modeling the interior of the patch, subtract that volume from the overall problem volume, which will cause its surfaces to default to PEC. Then consider applying an impedance boundary condition to the patch, if you care about resistive losses there.
Farrukh Mateen
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Posted: 1 decade ago 2014年8月3日 GMT-4 11:36
Hi Thanks for your response.

I dont really know how to subtract the volume of the patch from the volume of the whole model could you elaborate it a bit please.

Also in my efforts I managed to simulate the patch antenna "on top" of a substrate by making it as a 2D surface on the 3D substrate. The 2D is a PEC and the bottom of the substrate is a PEC too. Also I can change the material of the 2D patch as well. It seems to be working. Do you think this is a correct way of dealing with this issue.

I am using this model to receive radiation. So I use periodic (floquent) conditions on the four faces of the Air cube that I surround my antenna+substrate with with excitation port and Off port on the other two to have planner waves enter and shine upon my antenna.

Hi Thanks for your response. I dont really know how to subtract the volume of the patch from the volume of the whole model could you elaborate it a bit please. Also in my efforts I managed to simulate the patch antenna "on top" of a substrate by making it as a 2D surface on the 3D substrate. The 2D is a PEC and the bottom of the substrate is a PEC too. Also I can change the material of the 2D patch as well. It seems to be working. Do you think this is a correct way of dealing with this issue. I am using this model to receive radiation. So I use periodic (floquent) conditions on the four faces of the Air cube that I surround my antenna+substrate with with excitation port and Off port on the other two to have planner waves enter and shine upon my antenna.

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