need recommendation for WiFi antenna

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mzimmers
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need recommendation for WiFi antenna

Postby mzimmers » Wed May 23, 2018 9:07 pm

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.

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mzimmers
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Joined: Wed Mar 07, 2018 11:54 pm
Location: USA

Re: need recommendation for WiFi antenna

Postby mzimmers » Wed May 30, 2018 6:36 pm

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...

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loboris
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Re: need recommendation for WiFi antenna

Postby loboris » Wed May 30, 2018 7:35 pm

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

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mzimmers
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Re: need recommendation for WiFi antenna

Postby mzimmers » Wed May 30, 2018 8:18 pm

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
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Re: need recommendation for WiFi antenna

Postby Deouss » Thu May 31, 2018 12:49 pm

buy antenna tester

chrismerck
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Re: need recommendation for WiFi antenna

Postby chrismerck » Thu May 31, 2018 3:35 pm

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.

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mzimmers
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Re: need recommendation for WiFi antenna

Postby mzimmers » Fri Jun 01, 2018 3:24 pm

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
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Re: need recommendation for WiFi antenna

Postby Archibald » Fri Jun 01, 2018 7:21 pm

mzimmers wrote: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
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Re: need recommendation for WiFi antenna

Postby chrismerck » Wed Jun 06, 2018 2:29 pm

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.

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