PCB antenna not scannable

[Wade Brainerd]

Hi, I put a PCB antenna on my nRF52832 board, designed in KiCad as closely to the reference spec as I could, and manufactured on 4 layer by JLCPCB.

With the prototype in hand, and with the example Zephyr BLE code, nRFConnect for Android scan is unfortunately not finding the device. All SPI devices are working as well as console output via RTT, just not the BLE part.

Could I have made some mistake the PCB design? Is the chip not using my crystal for some reason? I followed the reference as closely as I could in KiCad.

The schematic and PCB layout of the hardware I am testing is at this commit (some tweaks were made later but haven't been manufactured): https://github.com/wadetb/tire-sensor/commit/e5b9437c4010035f12b5f04c34cb8954465011a6

Can anyone see what I've done wrong here? And for my next revision, should I stick with this PCB antenna or is there some similar footprint prefab option that would give better performance?

Thanks for any and all advice.

[Turbo J]

Layout looks like there is a ground plane below the PCB antenna? That won't work - usually. Most PCB antenna designs require that no metal is anywhere near them AFAIK.

NRF chips are very sensitive for the main crystal as these are constantly turned off and on. If you did not use one of the few specified parts, it probably won't work.

[Wade Brainerd]

Reading https://devzone.nordicsemi.com/guides/hardware-design-test-and-measuring/b/nrf5x/posts/general-pcb-design-guidelines-for-nrf52-series, it indicates that there is supposed to be a ground plane under this kind of antenna:

Monopole quarter wave, printed PCB antenna: This antenna is easy to make and easy to tune, and it only needs one shunt components for impedance matching in addition to the antenna length. Space: About 23 mm long and needs a minimum of 5 mm clearance to the ground plane.
See the white paper on monopole quarter wave antenna.