SMA connector (edge mount, through hole)with microstrip feedline

[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.

 

[jiripolivka]

Please find the specifications for connector users. It gives drawings as well as instruction on how to install through holes. In a double-clad PCB, ground must be perfect for a given frequency.

 

[rizwan183]

My working frequency is 3.5 GHz. as i found from an article ground and signal separation must not be more than a quarter wavelength at the max. frequency. I would appreciate alot if you could suggest me link or guide to such instructions along with drawings. Thank You

 

[Terminator3]

Check this out: https://www.digikey.com/product-detail/en/104631-HMC363S8G/1127-1100-ND/3588494
(click on the PCB photo to see it in bigger size).

I used similar looking but pretty cheap connectors. Just soldered them to 50 Ohm microstrips. No CPWs. Then there was cables to connect oscillator - lna - mixer - antenna - prescaler, all with SMA connectors. There was 4-5 RF cables interconnection and i still was surprised with result, i thought losses will be much bigger. Now i am only using this kind of SMA connector, it does require a through-hole. Only some additional ground on top for soldering.

If you have some measurement devices, just make one big test prototyping board.
Put 5 or maybe 10 microstrip lines (50 Ohm) Lines must be equal in length, and have SMA connectors on both sides. For each line you can use different PCB layout for different SMA connectors, etc.
Then you just measure insertion loss of each line. If you will see acceptable results, then you can continue to next steps of your designs.

You can ever do it without measurement devices! For example, you have some commercial WiFi router or something with SMA-connector for antenna. All you need is pair of SMA-cables and PCB-board i mentioned above. Then you just connect your board between WiFi router and antenna and see if performance degraded. You can see it from receiving range, signal strength indications, etc..

 

[rizwan183]

Hy terminator! could you please send me the link of the SMA you used for your design. the link you post use Edge mount. i am using 0.5mm thick double side board.bottom side is microstrip circuit and Top side is ground on which DRA antenna placed directly. it is not possible for me to place connector on top side. Because it will effect the antenna performance. edge mount is a feasible solution though. but i need to know how the connections are performed.

 

[Terminator3]

I used SMA-KE with 1.2mm gap on 1.0mm PCB. Cable used is RG402.
You can google for SMA-KE or SMA-KHD, and RG402 cable.