I put a (C-L-C) Pi Filter in series with my antenna trace on a new design, like so:
The reason you put one of these circuits in, as I understand it, is just in case, during compliance testing (i.e. FCC / CE) you have an issue with your antenna matching causing a failure, you have a decent chance of fixing it by populating appropriately sized inductor and capacitors.
So what is usually done to initially populate the board in that case, before you take it in for testing / certification?
- DNP the capacitors and populate a 0-ohm resistor in place of the inductor?
- DNP the capacitors and populate a 100-ohm resistor in place of the inductor?
- Guess at the value of and populate the inductor, and DNP the capacitors?
- Guess at the values of both the inductor and capacitors and populate both?
- Something else?
Feel free to rank these in preference order, and/or comment on the pros and cons of each. Thanks in advance for any demystification you can offer.