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[rizwan183]

Hello everyone, I am developing a double side pcb. one side is ground and other side is microstrip circuitary to feed the antenna. I need to design the footprints of the connector. i don't understand connectors at all. the throughhole connector got all four pins equal in length. i thought middle pin should be smaller than others or vice versa (how is four pin supposed to connect ground on opposite side while middle is supposed to connect microstrip). I don't want to use the option of middle pin with holes which is theoretical same as throughhole. same is true for edge mount, should i use ground around microstrip feeding point and then connect that ground with vias to the other side of pcb like CPW. detailed answer along with samle guide will be alot help.

sorry if i am being too naive. This is my first pcb.

[helix]

Chapter 4 of Eric Holzman's book can help you understand principles and tricks for microwave transitions.

http://www.amazon.com/Essentials-Microwave-Grounding-Artech-Library/dp/1580539416


Izadian's book is similar, but it's much older. It's worth a look as well:

http://www.amazon.com/Microwave-Transition-Design-Library/dp/0890062358

[rizwan183]

Hy helix! thanx for your reply. I have gone through the holzman Ch4. But i got confused. As for edge connector how to decide the separation between signal pad and ground pins pad. Also width of vias. In usual practices of connecting how you guys handle this issue. Thanks

Regards,

[helix]

I think you have 3 options:

1) Simulate the heck out of it with a full wave EM code (e.g., HFSS or CST). You will want to get the CAD models for the internal geometry and dielectric materials from the connector manufacturer... this can sometimes be difficult.
2) Build a lot of prototypes and test them on a VNA (maybe cut/tune with a razor).
3) Follow the connector manufacturer's guidelines as closely as possible with respect to substrate material, thickness, pad layout, and transmission line design and check performance on a VNA.

What frequency are you concerned with?

Even though it is designed for transition to coplanar waveguide, I've used this type of connector with microstrip at many GHz.

https://cinchconnectivity.com/OA_MEDIA/specs/pi-142-0761-861.pdf

[rizwan183]

Thanks alot helix. this pdf document gave me a pretty much good idea what to expect from manufacturer instruction manual. Also my working frequency is not much high. It's 3.5 GHz and board thickness is 0.5 mm (20 mils).

i would appreciate if you could share the sample of your connection of such connectors with microstrip. clear pictures of top and bottom side would be sufficient.