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Help Validating PCB Design

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pigrew:
For the antenna track, it looks short enough that being exactly 50 ohms may not be so important. Find a coplanar waveguide calculator online, and adjust your track width/spacing to match its result. However, I would move the inductor so that its pad rests directly in the middle of the RF line, so you do not have a stub.

I also see a few acute angles on the board that you should get rid of.

sokoloff:

--- Quote from: microcompiler on May 02, 2017, 07:05:15 am ---Regarding the connector on the top of the board I'm trying to stick to the HAT standard as close a possible.  This type of connector has two parts allowing you to stack boards if you by the long pin header.
--- End quote ---
That makes sense, but you still need the female part on the bottom of the board and male pins on the top of the board if I'm thinking about the problem correctly.

theatrus:

--- Quote from: pigrew on May 02, 2017, 03:16:38 pm ---For the antenna track, it looks short enough that being exactly 50 ohms may not be so important. Find a coplanar waveguide calculator online, and adjust your track width/spacing to match its result. However, I would move the inductor so that its pad rests directly in the middle of the RF line, so you do not have a stub.

I also see a few acute angles on the board that you should get rid of.

--- End quote ---

Yeah, agree - the super short length is going to forgive any minor mistakes. For a CPW (grounded) calculation on 2 layer FR-4, a width of about 35mil with a spacing of 8mil gets you to ~53 ohms, which is plenty close enough (as the FR-4 isn't consistent, etc etc). The current design looks more like 10/10 spacing/width which is 82ohms - not great.

Second the stub elimination advice.

h00p:
You have a typo in the UART/ACD/IO silkscreen.

ziggyfish:

--- Quote from: microcompiler on May 02, 2017, 07:33:24 am ---@ziggyfish - I also made the changes to account for an active antenna like this.  However, I'm not so sure I understand your comments about the 50-ohm impedance.  Would I just start with the 10-ohm that the datasheet suggests and then test the impedance once I get my first board and adjust R11.

--- End quote ---

The impedance I am referring too, and many commentators are referring to is the trace impedance.

To calculate the impedance of that trace, use this tool. Microstrip Impedance Calculator

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