https://devzone.nordicsemi.com/f/nordic-q-a/64602/antenna-trace-keepout-area-on-internal-layersHello, i have a question about keepout area under antenna trace in multilayer pcb. I have a 4-layer pcb, but substrate height between top layer and first mid layer isn&#39;t enough for good 50-ohm trace design, so i decide to make cutout in first mid layeren-USTelligent Community 13Fri, 07 Aug 2020 11:53:11 GMThttps://devzone.nordicsemi.com/thread/263593?ContentTypeID=1Fri, 07 Aug 2020 11:53:11 GMT137ad170-7792-4731-bb38-c0d22fbe4515:2eb6f6c6-30bf-4c36-950f-8dd77b520d6cAndrei<p>Thanks for your answer!</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/263587?ContentTypeID=1Fri, 07 Aug 2020 11:41:32 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d45e57b1-3ec9-4759-a97f-0780925ae11fAndreas<p>Hi,</p> <p>&nbsp;</p> <p>There is not one correct answer to this, but in general wider is better. If more narrow than the top layer opening then the middle layer board will disrupt how the electromagnetic field is distributed from the center conductor, and thus change the impedance. Infinitely wide does not mean infinitely good though, so no need to make it very much wider than the top layer opening, you typically want as large ground planes as possible too.</p> <p>&nbsp;</p> <p>Best regards,</p> <p>Andreas</p><div style="clear:both;"></div>