grounding with electrical circuit module in RF module

Please login with a confirmed email address before reporting spam

Hello everyone,

I have a problem with defining the lumped port and PEC boundary condition. In the attachment, the outer surface of the test object (not the sphere that is defined as air) is grounded using a defined lumped port and electrical circuit module. But the software gives an error mentioning that PEC is needed. How can I solve this error without any change to my model? I attached my model. I would highly appreciate it if you give me some advice.


6 Replies Last Post 2024年6月13日 GMT+2 18:14
Edgar J. Kaiser Certified Consultant

Please login with a confirmed email address before reporting spam

Posted: 3 months ago 2024年6月5日 GMT+2 19:14

Hamed,

a lumped port must connect two PEC or Impedance Boundaries. All your port definitions are pretty cumbersome and it is unclear what you want to achieve. Check examples and the documentation to learn about ports.

Cheers Edgar

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Hamed, a lumped port must connect two PEC or Impedance Boundaries. All your port definitions are pretty cumbersome and it is unclear what you want to achieve. Check examples and the documentation to learn about ports. Cheers Edgar

Please login with a confirmed email address before reporting spam

Posted: 3 months ago 2024年6月5日 GMT+2 19:53

Hello Edgar

I understand your point. I have just two lumped ports. One of them is to create an EM pulse, which is defined as a uniform. This port doesn't have any problem. My problem is the other one that is described as uniform. For that, COMSOL gives an error. This section (assigning a lumped port to the outer surface of the test object) is entirely correct based on the papers. I am looking for a way to fix the PEC error.

Hello Edgar I understand your point. I have just two lumped ports. One of them is to create an EM pulse, which is defined as a uniform. This port doesn't have any problem. My problem is the other one that is described as uniform. For that, COMSOL gives an error. This section (assigning a lumped port to the outer surface of the test object) is entirely correct based on the papers. I am looking for a way to fix the PEC error.

Dave Greve Certified Consultant

Please login with a confirmed email address before reporting spam

Posted: 3 months ago 2024年6月5日 GMT+2 20:33

I think you need to explain what you are trying to do.

As noted a lumped port must bebetweenconductive boundaries. You have selected for your lumped port conductive boundaries but they are all connected to each other. So there is no "between".

Physically a lumped port is appropriate when the electric field is expected to be roughly uniform between two conductors. In that case the voltage can be defined (by integrating along a line) and a current can be determined, again by integration. This is the case for the stripline image shown when you select a lumped port.

By the way, in order to be well-defined all emw and temw problems must have outer boundaries defined in some appropriate way. If you do not define a boundary as a conductor it must be either a port (a proper port, allowable because it is between conductors), a scattering boundary condition, or a PML boundary condition.

I think you need to explain what you are trying to do. As noted a lumped port must be *between* conductive boundaries. You have selected for your lumped port conductive boundaries but they are all connected to each other. So there is no "between". Physically a lumped port is appropriate when the electric field is expected to be roughly uniform between two conductors. In that case the voltage can be defined (by integrating along a line) and a current can be determined, again by integration. This is the case for the stripline image shown when you select a lumped port. By the way, in order to be well-defined all emw and temw problems must have outer boundaries defined in some appropriate way. If you do not define a boundary as a conductor it must be either a port (a proper port, allowable because it is between conductors), a scattering boundary condition, or a PML boundary condition.

Edgar J. Kaiser Certified Consultant

Please login with a confirmed email address before reporting spam

Posted: 3 months ago 2024年6月5日 GMT+2 23:08

I understand your point.

I don't think you understand the point. Your ports are not going to work. They are fundamentally wrong. You can see a lumped port like the two conductors of a coaxial cable, the shield and the center conductor. They need to be connected to two conductors in the RF device. E.g. the housing (shield) and some hot conductor in the device. COMSOL requires those conductors to be PEC or Impedance boundaries.

-------------------
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
>I understand your point. > I don't think you understand the point. Your ports are not going to work. They are fundamentally wrong. You can see a lumped port like the two conductors of a coaxial cable, the shield and the center conductor. They need to be connected to two conductors in the RF device. E.g. the housing (shield) and some hot conductor in the device. COMSOL requires those conductors to be PEC or Impedance boundaries.

Please login with a confirmed email address before reporting spam

Posted: 3 months ago 2024年6月12日 GMT+2 17:57
Updated: 3 months ago 2024年6月13日 GMT+2 17:24

I fixed the previous issue but I have another problem with defining lumped port and PEC boundary condition in COMSOL, saying that: Errors when compiling equations. The DAE is structurally inconsistent. How can I fix the problem?

I fixed the previous issue but I have another problem with defining lumped port and PEC boundary condition in COMSOL, saying that: Errors when compiling equations. The DAE is structurally inconsistent. How can I fix the problem?

Dave Greve Certified Consultant

Please login with a confirmed email address before reporting spam

Posted: 3 months ago 2024年6月13日 GMT+2 18:14

Apparently Comsol doesn't have a problem with your second port although I can't figure out why and I can't figure out what it would measure.

About inconsistent DAE- that happens usually when a circuit is impossible to solve for some reason. Usually it can be diagnosed by drawing the complete circuit and labeling all the nodes. However it is probably advisable to make sure the EM field calculation makes sense first by terminating the port in a resistor and checking whether the voltage across the resistor makes sense.

Apparently Comsol doesn't have a problem with your second port although I can't figure out why and I can't figure out what it would measure. About inconsistent DAE- that happens usually when a circuit is impossible to solve for some reason. Usually it can be diagnosed by drawing the complete circuit and labeling all the nodes. However it is probably advisable to make sure the EM field calculation makes sense first by terminating the port in a resistor and checking whether the voltage across the resistor makes sense.

Reply

Please read thediscussion forum rulesbefore posting.

Pleaselog into post a reply.

Note that while COMSOL employees may participate in the discussion forum, COMSOL®software users who are on-subscription should submit their questions via theSupport Centerfor a more comprehensive response from the Technical Support team.

Baidu
map