Simulation of radiated emission

Dear Sirs,
i am hardware designer and i'm having a problem with radiated emission from multilayer PCB. Can i use CST or Mentor tools for simulate and resolve this kind of EMC problem? In the past i used these software for microwave circuits design, but never for PCB with microcontroller on board.

Regards

Hello
I have proposal of other approach to your problem. Did you try to find source of problems using near field probe connected to spectrum analyzer?

I am just asking because building a model of your PCB may take a big amount of time (I am not familiar with CST - so I am not sure that you may import your design to CST). Additionally simulation time may be long too.

Best regards

Hi,
simulations in EMC are in best cases 60dB away from any measurement, which make them useful to only get a sense of which trace could match a wavelength.
I have used an EMC analyzer to locate the source.
Step1: after receiving the EMC test report, look at the frequencies above the limits.
Step2: with the EMC analyzer try to locate the source. get a reference measurement before you make any changes.
Step3: potential explanation:
--> not enough decoupling cap (use PDN tool from Altera website to select the right number of capacitors). It is very good tool and it is not specific to altera devices.
--> Look at the grounding approach at system level and try to identify the DC current return path (the AC return path is under the PCB trace in the neighboring plane). if the return is on the chassis then it will generate common mode current and carry the noise and generate EMI.
--> Try shielding and reduce the edges where possible.

Remember maxwell equation, the Gauss law (integral form), you are testing the E field in the EMC chamber.
Good luck

Thanks to everybody.

The PCB "aggressor" is a parts of a system; the cable emission was measured with a capacitive clamp. One measure over the limit is @50MHZ (about 50dBpW). This is even one of foundamental frequencies on board. I want make some correction of terminantion at the ports, and try to get a measure of radiation with a near field probe.

It seems like coorect?? Where i can find a good documents for make a near field probe???

Hello
Below there is a link to probe manufacturer.
http://www.hameg.com/330.0.html?L=0
The cost should be less than 900 Euro.
If you want to made near field probe you may use semi rigid coaxial cable like below.
**broken link removed**

If I find some articles about making near field probes I will send you an information.
Best regards

Hello
Please find in attachment and link below some pictures of near field probe.

http://www.conformity.com/artman/publish/printer_168.shtml

Best regards

This is a relevant information for you.

**broken link removed**