Raspberry Pi 3 External Antenna

Description

The Raspberry Pi 3 with integrated WiFi and Bluetooth is awesome, right? I got mine on 7 March 2016. Upon close inspection, one can't help but notice the little spot on the underside labelled J13 - close to Pin 1 (3.3Vdc) on the GPIO header. It looks like the footprint of a Hirose U.FL connector...

Details

UPDATE 19 MARCH 2016

Got my U.FL to RP-SMA pigtails with antennas. I have a few nice black cases by OneNineDesign that came with Rapsberry Pi 2 kits by CanaKit. I modified one for the Pi3 plus pigtail & external antenna.

I cut a little notch in the plastic for the wire to come up from underside the board, hollowed the Pi2 LED holes to pass the cable thru, then drilled a hole above the power connector to mount the SMA connector.

Then finally I mis-measured & ended up with a terrible hole for the Pi3 LEDs to shine thru. :P

See additional link to Google Photos album called Case Modification.

-KJ

ORIGINAL:

With my Fluke multimeter I checked continuity from the radio antenna output thru the two tiny zero-ohm resistors, all the way to the metallic looking parts of the onboard antenna chip. I got beeps all the way.

I checked continuity from the radio antenna output to the little gold square where the U.FL center pin contact might go - nada, open.

Alright, time to potentially ruin my brand new Pi 3!

I imaged an SD card with Raspbian Jessie Lite, setup everything to my preferences, and installed wavemon. After each step of abusing my Pi 3's circuit board, I let it cool, inserted the SD card & powered up, SSH'd in, checked wavemon, then took photos.

I have linked to my Google Photos album so you can see all the pics I took. For the pics I've uploaded to this project, I used Skitch to screenshot & markup with the arrows and text.

There is ground plane on the opposite side of the exposed J13 rectangular pad, so I scraped off some solder mask, then I tinned up all three spots.

I took a wifi module out of a junk laptop then with my heat gun and tweezers I lifted both U.FL connectors from it.

Heat gun and tweezers again, I placed the U.FL connector on J13.

I snapped on an antenna lead I pulled out of the same junk laptop - oops, when it swivels it will short the Pi3's ground plane to GPIO pin 1 - 3.3Vdc. I mixed up a little bit of non-conductive epoxy and put a blob over that pin to insulate it - problem solved.

I put a tiny piece of solder at the radio's antenna output & the dot where the U.FL square pad trace comes up, melted it with the heat gun. Check continuity again with the meter - YAY! Got continuity with both the onboard antenna chip and the U.FL center pin.

I booted it up and ran wavemon to check signal strengths with & without the laptop antenna lead connected, not much difference.

So now everything still works, time to go all in! I fired up the heat gun again, with a needle pick I flicked away the zero ohm resistors (I have no clue where they went, so tiny!) that run along the little J-shaped trace thru the via to the onboard antenna.

I checked continuity again - onboard antenna nada, U.FL center pin game on!

Finally I booted up without the laptop antenna lead. I was able to SSH in and run wavemon, my signal strength to the AP 10 feet away was -66 dBm, and my neighbors didn't even show up on F3-scan. I snapped on the laptop antenna lead, and BLAM! My wifi was -29 dBm, and the neighbors showed up in wavemon as I expected.

With this modification a Pi3 can easily mount inside a metal enclosure. My omni antennas with U.FL to RP-SMA pigtails will arrive tomorrow. =)

Components

1 × Raspberry Pi 3

1 × Donor laptop wifi module

Discussions

offtherails2010 wrote 01/03/2020 at 13:46

AWESOME Article !!!
Thank you SOOOO MUCH !!!!

This is what hackaday is all about, sharing good knowledge and great ingenuity from the general public helping others to get their existing tech made better - well done Sir !!!

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Wojciech wrote 12/14/2019 at 15:58

Dear Chris, this external antenna will work only for WiFi connections or for Bluetooth too? Please reply.

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Sven Anders wrote 05/17/2019 at 10:45

Hi!

Thanks for you hardware hack.

Is is necessary to remove both 0-Ohm resistors or will the first be enough?

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Jakub Krzaczek wrote 03/07/2019 at 19:33

Have you tried anything similar with RPI3 A+?

It doesn't seem to have that footpad and the only helpful image I found was from the FCC studies:

https://fccid.io/png.php?id=3777895&page=4

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harvey.gordon wrote 11/13/2016 at 14:23

I did the same thing using spares from an old set to box. It is a small coax cable with on one end a U.FL connector and on the other end a little piece of printed board that play the role of antenna and that you can stick in the box. But I do not get much improvement. Could you give me the references of the connector and of the external antenna you use.?

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mvguran wrote 03/23/2016 at 02:29

hi, could you please help me?? i just broke the black silver thing, called L8 i think, right next to C241 in the picture, which jacksonliam uploaded. My wifi stop working at all :( Can you please tell me what it is, and where i can find it. Thanks so much in advance. Maybe later i can think about getting an ext antenna :)

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Gabriel Chira wrote 01/31/2019 at 07:54

it's an inductor, a passive component for the wi-fi chip, apparently.

you could look at the schematic and find a replacement smd inductor of the RIGHT value, since this is RF dark arts and magic smoke territory

best of luck my friend

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Ward wrote 03/15/2016 at 17:49

Nice work! I was wondering if the solder blob method would do the trick. Here's my writeup of a couple of different methods of adding an external antenna.

http://www.dorkbotpdx.org/blog/wramsdell/external_antenna_modifications_for_the_raspberry_pi_3

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Kris Jacobs wrote 03/19/2016 at 15:05

Aha! I found & read that just hours after I published this Ward - great article, I love the spectral analysis!

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jacksonliam wrote 03/14/2016 at 21:50

Thanks for this, useful info! My image of this unmodified pi might help make things a little clearer:

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Kris Jacobs wrote 03/19/2016 at 15:05

Wow great photo Jackson! Thank you!

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Austin Fraley wrote 03/11/2016 at 12:16

The real question is how do you plan stave off all the women throwing themselves at you?

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Raspberry Pi 3 External Antenna

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