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Published Saturday 04 March 2017
Categories: Raspberry Pi |

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Raspberry Pi Zero W external antenna mod

With the release of the new Raspberry Pi Zero earlier this week we ordered one from The Pi Hut to use with our expansion boards (they all work without any problems) and one from Pimoroni to use with our barcode scanner project.

The new Raspberry Pi Zero W has built in Wi-Fi and so we thought this would be better than the USB dongle which we are using with the barcode scanner.

Upon receiving the new board we noticed that the Raspberry Pi foundation have left a space and jumper pad for a U.FL RF connector to use with an external antenna.

Connector Pads

Connector Pads

We already had a suitable Wi-Fi antenna and so we ordered the U.FL connector and a short coaxial cable assembly from Farnell.

The parts ordered are:

HIROSE(HRS)  U.FL-R-SMT-1(10) and MULTICOMPR-134G7210150CA

On the Raspberry Pi PCB there is a component which appears to be a zero ohm resistor (0201 size 0.6mm x 0.3mm) which links to the pcb antenna or can be turned 45 degrees to link to the U.FL connector bypassing the internal antenna.

Component to rotate

Component to rotate

We carefully removed and rotated the resistor to the U.FL link pad and then soldered the new U.FL connector to the board.

Link rotated and the new U.FL connector fitted.

Link rotated and the new U.FL connector fitted

The connector fitted to the Raspberry Pi Zero W

The connector fitted to the Raspberry Pi Zero W

To test the new external antenna compared to the built in PCB antenna we used the following command to scan for available Wi-Fi networks.

sudo iwlist wlan0 scan

The following table shows a list of networks found and their signal strength and quality readings. Most networks showed an improvement with the new external antenna and our home network had a much greater signal strength.

      Internal Antenna External Antenna
Network Channel Encryption Quality Signal Level (dBm) Quality Signal Level (dBm)
Net1 6 WPA2 26/70 -84 27/70 -83
Home network 13 WPA2 50/70 -60 68/70 -42
Net2 1 WPA2 27/70 -83 37/70 -73
Net3 1 WPA2 27/70 -83 37/70 -73
Net4 6 WPA2 26/70 -84 27/70 -83
Net5 6 off 27/70 -83 30/70 -80
Net6 1 off 31/70 -79 37/70 -73
Net7 11 WPA2 28/70 -82 29/70 -81
Net8 6 WPA2 27/70 -83 26/70 -84
Net9 11 off 28/70 -82 31/70 -79
Net10 1 WPA2 27/70 -83 25/70 -85
Net11 6 off 28/70 -82 23/70 -87
Net12 6 off 26/70 -84 22/70 -88
Net13 6 WPA2 28/70 -82 21/70 -89
Net14 11 WPA2 29/70 -81 32/70 -78
Net15 11 WPA2     14/70 -96
Net16 1 WPA2     30/70 -80
Net17 1 off     30/70 -80


Testing the Raspberry Pi Zero W with the built in antenna

Testing the Raspberry Pi Zero W with the built in antenna

Testing the Raspberry Pi Zero W with the external antenna

Testing the Raspberry Pi Zero W with the external antenna

Please note this will invalidate the FCC certification.

The photo below shows the new modified Pi attached to the Barcode scanner project we are working on. The Raspberry Pi Zero W is mounted between the power supply/controller PCB and the touch screen so the onboard antenna would be shielded by both boards.

Barcode scanner pcb




04 March 2017 at 12:00 am

It's fantastic that they included a place on the board to solder the component. Very thoughtful!


04 March 2017 at 1:00 am

If you look carefully at the pad arrangement, it's more likely that the u.fl jack was there so the onboard resonant antenna could be connected to external test equipment for tuning. Removing the pads in the final board rev would've affected the tuning, so they left it. Using it for this purpose only requires moving the component 90 degrees, and it fits properly across the pads once you've done so. The 45-degree arrangement is clearly not what the pads were designed for, but it serves a purpose that's more useful to the end-user.

Daniel Bull

04 March 2017 at 2:00 am

Its probably more likely that it was there for diagnostics and not removed. Although I do agree its quite useful that they left it there :)


04 March 2017 at 3:00 am

It's actually there as a requirement for certification/regulatory testing. A conducted RF port is needed on the final product.

Daniel Bull

04 March 2017 at 4:00 am

Thats Lotus, thats good info, well worth knowing.


05 March 2017 at 12:00 am

Also in my experience RF stuff is static sensitive, so please be careful!
Maybe someone can figure out how to use the now-redundant internal antenna for triangulation or similar?
On certain chipsets its possible to specify antenna I or II so it might be feasible ?


05 March 2017 at 1:00 am

The link resistor allows you to use the built in antenna or redirect the RF signal to the U.FL socket by turning the resistor 45 degrees


05 March 2017 at 2:00 am

Ah. My bad, sorry. I see that the internal antenna is basically a special cavity inside the board so each unit is "tuned" correctly although the handy feature here would be further fine tuning using a tiny drop of UV set glue for those times you can't quite fit an external antenna in the unit. Protip, this is also handy for patching up damaged USB-micro connectors after resoldering, adding pink LEDs in place of the vanilla green/yellow and other micro-soldering mods.


06 March 2017 at 11:59 am

Nice! However you should also probably change your Wifi network to not use ch13 (Google wifi channels for more info).

Till O'Rrly

06 March 2017 at 12:59 pm

Only in the USA. There you can use it to hide you WiFi :)


06 March 2017 at 1:59 pm

I cant find anything that says that i cant use channel 13 in the UK, seems only the USA dont allow it?

Mike Petonic

07 March 2017 at 12:00 am

Nice find! Thanks for sharing... This could come in very handy for some of those iOT applications in remote parts of the house that the W is going to fit into.

Colin Russell Conway

08 March 2017 at 10:59 am

Shouldnt be too difficult to sort out a spdt switch, like on the redbear labs IoTpHAT https://redbear.cc/product/ Although I'm not sure about any that would fit directly instead of the 0 ohm resistor I'm not sure if longer traces might have a negative effect.

Steve Mann

08 March 2017 at 11:59 am

The zero-ohm resistor is common in mass-produced boards where machines do 99% of the assembly. in through-hole assembly we would have used a simple jumper.


01 April 2017 at 8:59 am

Excellent Tutorial, and nice photos.


12 July 2017 at 9:59 am

Nice mod. I have a question. Do you think that the bluetooth module also uses this antenna and thus would get its range increased as well?


12 July 2017 at 10:59 am

I think the bluetooth module must use the same antenna and so its range would also increase.


21 August 2017 at 8:59 am

Thanks for excellent tutorial. You're not breaking against any regulations if you for example create a packet sniffer. Then there is no Tx so you can add a 30dBi antenna if you want. For transmission, I also doubt the radio chipset that sits there at the moment gives 20dBm. It's very common in for example phones that Wi-Fi gives maximum 14-17dBm in Tx mode (compare with up to 2W for cellular radios, but those use power adjustments while the Wi-Fi Tx power is on a constant level). Question: is it possible to squeeze an SMA connector on to that pad rather than a UFL? Don't like UFLs. They come off easily.


21 August 2017 at 9:59 am

I dont think a sma would fit on the pad, but you could use a short ufl to sma socket lead and then glue the wire to the board to stop the ufl connector from coming away.


27 October 2017 at 8:59 am

This really is a great idea and should be a factory-feature. I am going to be mounting my Pi Zero in a fully sealed aluminum enclosure, and I need a coax connector at the outside for an antenna. This article was VERY useful.


30 November 2017 at 8:59 am

Interesting to see that external antenna does not works "far much better" than the original.
When you tested the external antenna, it was like on the pictures, not up/down like a normal antenna? That may explain small difference?

Steve Mann

08 December 2017 at 9:59 am

Since the Pi-ZW is certified as an FCC Part 15 device (https://fccid.io/2ABCB-RPI0W), any antenna must be an integral part of the device and not user-changeable.

From the Part 15 regulations (47 CFR 15.203 Antenna Requirements)
"... each Part 15 transmitter must be designed to ensure that no type of antenna can be used with it other than the one used to demonstrate compliance with the technical standards. This means that Part 15 transmitters must have permanently attached antennas, or detachable antennas with unique connectors. A "unique connector" is one that is not of a standard type found in electronic supply stores."

Technically- it is an FCC violation to modify the antenna. In the real world, nobody knows if you peed in the pool.


08 March 2018 at 6:08 pm

Hi I have a small question I lost the resistance by desoldering. I wanted to know the value of the resistance to be able to replace it


08 March 2018 at 9:32 pm

It is a zero ohm resistor to link across the pads.

Robert Morgan

02 April 2018 at 9:43 am

@Steve Mann

But, if you're a licensed amateur radio operator, you have license in the 2.4ghz band, and wifi transmitting is then covered under Part 90 rather than Part 15.
Fun to know.


02 April 2018 at 10:41 pm

What about doing in some oter way?....

For not so "precise" soldering:

Removing the "dummy load" resistor and coils near the trapezoidal area, then "bridge" the two connections (pcb antenna and connector for the external).

I think it will make thing easier for thos without microscope. ;)


29 June 2018 at 4:20 am

Since it's just a 0 ohm resistor, do you even really need it? You could just remove it and put a piece of wire to patch over.. Or even leave it and add the wire in as well, I mean, cause is there any harm in having both antenna's attached at the same time? lol


29 June 2018 at 9:43 am

OkinSama, If the resistor was left in place giving two antennas it would cause an rf impedance mismatch on the driver circuit which could damage the WiFi chip.


01 July 2018 at 12:38 pm

I found your article by accident... Had a zero w idling around here and had the opportunity to get all parts for <8€ locally...

I hammered everything together with a 50€ el'cheapo soldering station and a 10x Watchmakers magnifying glass.
All in all, took me less than 15 minutes and my range doubled with a Tp-Link 29cm 8db antenna.

Thanks for the idea :)

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