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I am building a PCB business card with an NFC chip and a WS2812B LED display (powered by a USB-C port, NFC is not connected to the LEDs). Right now I have a ground plane on the side of the antenna (not connected to either the NFC chip nor the antenna), and a +5V plane on the opposite side of the antenna (also not connected to the NFC circuit). Here are screenshots from both sides:

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Would the planes interfere with the antenna in any significant way? And should I change the grid pattern to a normal plane? (The grid was a cosmetic choice) I am using this chip for NFC, and the antenna is the same as the antenna from this tutorial.

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  • \$\begingroup\$ I think the LEDs may be okay, but that ground fill is likely to hurt your signal. This antenna is primarily inductive; the fill around it creates a parallel loop, which turns this into a transformer (with short-circuited output). Try to keep your traces perpendicular to the antenna tracea, and at least break up the fill so it will not conduct in a loop. \$\endgroup\$ – mbedded Jul 25 '20 at 4:53
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I recommend checking it in some finite element electromagnetic simulator, like Microwave Studio or openEMS, but it may be faster to actually make the PCB and test.

It is hard to say right off the bat if your ground and power planes are going to act as shielding or reflectors. My guess is that they are actually going to act more like reflectors.

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  • \$\begingroup\$ Thanks, I'll be sure to try using the tools you described. \$\endgroup\$ – Yonatan Avhar Jul 25 '20 at 6:45
  • \$\begingroup\$ I just looked at both of the tools that you mentioned, and Microwave Studio is a paid software that requires me to contact the developer just to try it (which I assume would be quite expensive), and openEMS is an addon for a MATLAB, which also isn't cheap. Do you know any program that won't cost me an arm and a leg? \$\endgroup\$ – Yonatan Avhar Jul 25 '20 at 8:35
  • \$\begingroup\$ @YonatanAvhar: You might look at 4nec2. \$\endgroup\$ – JRE Jul 25 '20 at 10:18
  • \$\begingroup\$ @YonatanAvhar openEMS works also with Octave which is free and open source. Though 4nec2 that JRE suggested may work. I will check it out myself because it looks interesting. \$\endgroup\$ – Kristoffer_S Jul 26 '20 at 1:45

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