Information on PORTS

[kumararunpb]

Hi
I need info on ports (wave and lumped ports)
I am planning to go with hfss for connector modeling and analysis .
I need info on which port to use and how to use the same.

Thanks in advance

[Jason]

Hi,

For a connector you basically have two options. One is to use short lead-in and lead-out traces going to and from the connector. You could then use wave ports at the other end of the trace. If you want to then remove the influence of the trace you could use wave port de-embedding.

The second option is to use a lumped ports. I am not sure of your particular pin assignment and signal configuration, but you could use the lumped port placed signal endedly between signal and ground on both sides of the connector. Keep in mind, that it all comes down to how the connector will be used in your application; a lumped port connected to a neighboring ground will give a different answer then a wave port excited with lead-in/lead-out traces, for example, due to differences in the return current distribution.

For general info on wave ports and lumped ports I would recommend Dan Swanson's book "Microwave Circuit Modeling using Electromagnetic Field Simulation" or Chapter 2 of Novak-Miller's book "Frequency-Domain Characterization of Power Distribution Networks".

Thanks
Jason

[kumararunpb]

Hi Jason,
Thank you very much for your reply ,it was quite useful.
I am planning to model a mated connector assembly with cable assembly on both sides.So how to give the port assignment .
Since I am not using Connector soldered to PCB trace out is not possible.
Can you suggest me the best method to get accurate results.


Regrds,
Arun

[Jason]

Not sure what kind of cable you are using but if it is coax, I would consider using a wave port on the coax some distance away from the mated connector such that the discontinuity (i.e., the connector) is not too close to the port. Coaxes permit a very nice wave port launch due to the symmetric ground configuration around the center conductor. You can then use wave port de-embedding to move the measurement point to the connector.

Jason

[kumararunpb]

Dear Jason,
I am using coax with 4 conductors, on both sides of mated connectors.I have the total length as 1m in which mated connector comes in middle.This length I guess can be achived by deembedding.
My doubt is if its a coax cable with 4 conductors how to go about assigning wave port.
And also I am planning to make spice model from this ,so should any other extra consideration must be taken for that?
How good hfss is making spice models from S parameters?
I am new to hfss and this field so I am a bit shaky with the port,boundary assignment etc.
Please can you help me if you have any experience in spice modeling of connectors and analysis.

Thanking you

Arun

[kumararunpb]

Hi Jason ,
I also had doubt in models.Intersection
Since I am using connectors ,I get a lot of intersection errors.I tried to make it ok with object misalignment but was of no use .Then I tried subracting it then the whole geometry got deleted .Then I subtract with clone option ,then the error was gone.Just wanted to know if this is the right procedure to avoid intersection problems.

Regards,
Arun

[sjapollo]

The best way to avoid intersection problems is a feature that was introduced in HFSS v11. Go to HFSS / Set Material Override. This basically tells HFSS that all metal object will override conductors which will eliminate the need for any subtractions.