ESP32 PCB vs. External Antenna

[Tommmmms]

Hi All,

This is my first post in this forum.

I plan to install an IoT system powered by an ESP32_WROOM_32 module inside a metal material light canopy -- imagine the ESP32 module enclosed in a metal puck.

My concern is that with the ESP32 module completely enclosed in the described metal enclosure, I would then need a way to radiate the RF out of the enclosure. This means, the ESP32_WROOM_32 with the printed PCB antenna would likely be a poor choice.

I imagine the alternative would be to use the ESP32_WROOM_32U instead which replaces the PCB antenna with an U. FL pin.

Questions:
1. What are some of the compatible antennas that could connect to the U. FL pin of the ESP32U modules
2. In order to minimize cost, could I opt for a short bare wire antenna without the finger-diameter sized plastic enclosure like those seen on a router antenna. Based on my research, this would probably not work since those plastic structures enclose copper coils crucial for the "omni-directionality" of the antenna

Any other suggestions that would help to improve RF performance inside metal enclosure would be appreciated.

Cheers,

Thomas

[doooku]

Hi!

Enclosing RF module in a conductive (metal) enclosure is not a good idea in general, as it acts as effective radiation shield for EM waves. It may depend on the physical properties of the metal case. If it's cage (with sparse grid) or it has a lot of holes, it may work (though it will have negative effect on the performance).

Your idea with the ESP32_WROOM_32U module is valid. The best solution would be to use some 2.4 GHz antenna with coaxial cable terminated with U.FL connector (antenna must be positioned outside of the metal case). Antenna should also have 50 ohms characteristic impedance.

Even a simple monopole (wire) antenna has omni-directional radiation pattern (in horizontal plane). However, I would suggest buying antenna, not trying to make it yourselves. You will find radiation pattern in the datasheet for the antenna. Any omni-directional, 2.4 GHz, 50 ohm antenna should be ok.