How to fix SMA Rosenberger footprint with Microstrip line

[rizwan183]

How to fix this design rule problem in Altium. Why I have problems while connecting signal pin to microstrip. And should i send ground pin footprint on bottom layer. Any Suggestions? attached is a picture. Sorry for such a basic Question.

 

[FvM]

Obviously, the top ground pins must not short the coupler traces and should have some distance to it not to disturb their impedance too much. So the PCB size should be adjusted, or you need to cut the pins manually.

Usually you have pads for the top ground pins, connected to the ground plane by multiple vias in case of a microstrip.

 

[rizwan183]

I want to connect ground pins of sma to bottom ground plane is that ok to shift to bottom layer???and signal pin and coupler are on top layer. when i place signal pin on couple it becomes short. how to solve this issue. top layer does not have any ground plane.i can extend the size.No issues.

 

[volker@muehlhaus]

Use a different connector (flange type). Your design will not work well.

 

[rizwan183]

Volker please share your reasons also if you can comment on my doubts. actually i need feeding circuit made of some couplers to feed antenna on other side. So i can't place connector on other side.
Regards

 

[rizwan183]

Most of my concerns may be solved by assigning names to the nets. But I am not sure how to name in PCB file. Also i am not sure if it is standard procedures for RF PCB design. I have never send pcb to manufacturer till now. I hope many of the people on this forum has gone through these steps many times. I hope from you guys to explain to me on very basic level. I am sure these are very minor issues. I am posting this because none of the forum satisfy me this regards and also I don't have such expertise in my surroundings. I will be very thankful for this.
PS: My frequency of operation is 3.5 GHz.

 

[FvM]

Use a different connector (flange type).

Nothing has been said yet about a case where a flange could be mounted.

Edge mounted SMA gives best RF performance for a bare PCB. As said, it would be better to connect the top ground pins, but without it, connector VSWR can be still acceptable. If you have a throughplated PCB, I don't see why you won't place top ground pads with vias.

Sufficient distance of the ground pins respectively pads to the coupler structure is required anyway.

 

[rizwan183]

Why circuit turn to green. how to solve this issue?
For top ground pads i can add vias with a distance less than quarter wavelength longer line for better VSWR. No issue.
Help me taking a step from theory to practical design.

Best Regards,
Rizwan

 

[volker@muehlhaus]

Volker please share your reasons

Looking at your picture, you build extra length = series inductance in the ground path between SMA coax and PCB line.
This is an example for bad design with too much length:
https://apollo.open-resource.org/_media/lab:mr3020-antenna-rpsmamod.jpg?tok=ef4851

You need a good, very short ground path. If you prefer edge mount connector, it could be like this:
**broken link removed**

 

[ferdem]

You can see the error(s) by right clicking the green place, there should be "Violations" in the right click menu. You can also run DRC(design rule checker under Tools menu) to see errors. Design rule errors can be fixed or they may not be important. You should be careful about whether there is a mistake in your design.

 

[rizwan183]

Thank You guys for your valuable suggestions. My only problem was software understandings. Any ways your valuable suggestions are alot helpful too me. Now I get things as here