need recommendation for WiFi antenna

[mzimmers]

Hi, all -

My company is looking into building a product based on the ESP32 module. We began with the WROOM, but we're concerned about whether the integrated antenna will give us adequate range. So, we're considering using the WROVER-I and an external antenna. Does anyone have a recommendation for an antenna for use with this module?

Thanks.

[mzimmers]

Hmm...no responses. OK, then let me ask this: is anyone aware of a spec (or guidelines) for the selection of a compatible antenna?

Thanks...

[loboris]

Why selecting an external wifi antenna for WROVER-I would be any different then selecting the antenna for any other wifi device ?

[mzimmers]

It might not be. Some people have told me, though, that there's a certain art to matching antennas to WiFi modules, and I just wanted to know what anyone else had done. My early indications are the antennas I bought to test with aren't doing much, but there's a lot of unknowns at this point.

[Deouss]

buy antenna tester

[chrismerck]

Good question. Yes there's a bit of an art to antenna matching, but the good news is, ESP32 is no different than any other WiFi device.

You need to be concerned with two things: impedance matching, and antenna frequency range. WiFi+BLE frequency range is common world-wide, and the ESP32 uses a 50-ohm impedence on the antenna output, which is also the standard.

So, any 50-ohm antenna with an appropriate connector (such as UFL for WROOM-32U) will work. Example: https://www.digikey.com/product-detail/ ... ND/2267896

Hope that helps.

[mzimmers]

Hi Chris -

Thanks for the information. I've discovered that most of the antennas that meet our size requirements are of very little gain (1-2 dBi) so we'll probably just stick with the integrated antenna. (I tried a couple external antennas, with no noticeable improvement, though I didn't remove the integrated antenna, so that might have messed things up.) I appreciate your feedback.

[Archibald]

I've discovered that most of the antennas that meet our size requirements are of very little gain (1-2 dBi) . . . .

ESP32 modules may not have such a good radiation pattern as omnidirectional aerials.

[chrismerck]

Higher gain means higher directivity. That's only a good thing if you can control the direction the antenna points. You can look at polar plots of the radiation pattern in the specs for an antenna you are considering.

An "ideal" antenna for portable / uncontrolled orientation use would be 0dBi -- also known as "isotropic", that is, radiate evenly in all directions.