Notupus
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Raspberry Pi 4 External Wifi Antenna

Fri Mar 13, 2020 9:27 am

The Raspberry Pi 4 apparently has a transmit power of 31.00 dBm which could be used for long range WiFi using a directional antenna.
So in order to add a connector on the RPi 4 what would I need to buy and do?

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jahboater
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Re: Raspberry Pi 4 External Wifi Antenna

Fri Mar 13, 2020 9:45 am

You could buy a USB Wifi adapter, many of which have an SMA socket so you may choose the antenna.

You can't modify the Pi (it may not even be legal).

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bensimmo
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Re: Raspberry Pi 4 External Wifi Antenna

Fri Mar 13, 2020 11:01 am

They'll not advise you on here (legal reasons), nor will actual methods be discussed a lot.

But if you search for it you'll find how.
It is the same method used on the 3B+ as it has the same layout.

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davidcoton
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Re: Raspberry Pi 4 External Wifi Antenna

Fri Mar 13, 2020 11:31 am

jahboater wrote:
Fri Mar 13, 2020 9:45 am
You could buy a USB Wifi adapter, many of which have an SMA socket so you may choose the antenna.

You can't modify the Pi (it may not even be legal).
Further, modifying the Pi will invalidate CE and FCC approvals, and any remaining warranty. Go the USB adapter route.

EDIT: clarified what is potentially illegal and what is permitted.
Last edited by davidcoton on Fri Mar 13, 2020 10:42 pm, edited 1 time in total.
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wolf.z
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Re: Raspberry Pi 4 External Wifi Antenna

Fri Mar 13, 2020 9:12 pm

Where did you find the spec saying Pi4B has 31dBm transmit power? However,

By modifying any radio device its EU or FCC approval will most likely loose validity. When buying a radio with an antenna connector, you are allowed to change the antenna in effect and will not loose approval.
With a directional antenna you have to reduce the transmit power depending on related limits of the frequency band used. You have to strictly stay below a limit of Equivalent Isotropically Radiated Power EIRP. Equivalent radiated power is not the same as transmit power.
In effect, 31 dBm transmit power of the Raspberry is not the outstaning property targeting a No 1 choice as a long range WIFI device. In case you'd succeed attaching a 20 dB gain higly directional antenna you had to bring down the Pi's transmit power down to 10dBm in order to maintain the EIRP limit of 30dBm for selected 5GHz bands or to even lower 0dBm in the 2.4GHz band.

If you already know what EIRP is and what you are doing with directional antennas, proceed. Despite loosing any approval, you most likely will not radiate something, that's beyond the very scope of any approval - except for too much radiation.
In any other case, spend your time reading about transmit power, equivalent isotropically radiated power, antenna gain first.

doppler
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Re: Raspberry Pi 4 External Wifi Antenna

Sat Mar 14, 2020 5:52 pm

All forgetting one thing. And it's something not generally known. If Notupus is a licensed Amateur radio operator. He could go on channel 1 (2.4GHz) setup a MESH node and transmit 1.5Kw (the max allowed). Possible (yes), Probable (not)

All of the above would require modification of the PI, and he would be responsible for everything being in compliance to license.

I always thought the antenna on PI's since the 3 was inadequate. Diversity antenna systems have always been the norm when you want to hear and be heard. The best way to do it would be to separate the 2.4 and 5GHz as two different paths. Allowing specially tuned antenna's (directional opt).

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davidcoton
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Re: Raspberry Pi 4 External Wifi Antenna

Sat Mar 14, 2020 5:56 pm

doppler wrote:
Sat Mar 14, 2020 5:52 pm
All forgetting one thing. And it's something not generally known. If Notupus is a licensed Amateur radio operator. He could go on channel 1 (2.4GHz) setup a MESH node and transmit 1.5Kw (the max allowed). Possible (yes), Probable (not)

All of the above would require modification of the PI, and he would be responsible for everything being in compliance to license.

I always thought the antenna on PI's since the 3 was inadequate. Diversity antenna systems have always been the norm when you want to hear and be heard. The best way to do it would be to separate the 2.4 and 5GHz as two different paths. Allowing specially tuned antenna's (directional opt).
It would be difficult to make a WiFi transmission comply with a (UK) amateur licence.
Note also that power limits and frequency allocations in Amateur licences vary from country to country.
Location: 345th cell on the right of the 210th row of L2 cache

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bensimmo
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Re: Raspberry Pi 4 External Wifi Antenna

Sat Mar 14, 2020 8:13 pm

doppler wrote:
Sat Mar 14, 2020 5:52 pm
All forgetting one thing. And it's something not generally known. If Notupus is a licensed Amateur radio operator. He could go on channel 1 (2.4GHz) setup a MESH node and transmit 1.5Kw (the max allowed). Possible (yes), Probable (not)

All of the above would require modification of the PI, and he would be responsible for everything being in compliance to license.

I always thought the antenna on PI's since the 3 was inadequate. Diversity antenna systems have always been the norm when you want to hear and be heard. The best way to do it would be to separate the 2.4 and 5GHz as two different paths. Allowing specially tuned antenna's (directional opt).
If it works for most people, then it is adequate.
The Pi3 original one was adequate, just had the problem of being easy* to knock of the white cuboid (Though would still work :-) to an extent)


* I have three of them now with them off. Just general use and storage for kids.

LTolledo
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Re: Raspberry Pi 4 External Wifi Antenna

Sat Mar 14, 2020 10:36 pm

just use USB WiFi adapter with user configurable antenna (that is allowed by the laws in your location)
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

wolf.z
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Re: Raspberry Pi 4 External Wifi Antenna

Fri Mar 20, 2020 9:14 pm

doppler wrote:
Sat Mar 14, 2020 5:52 pm
...If Notupus is a licensed Amateur radio operator. He could go on channel 1 (2.4GHz) setup a MESH node and transmit 1.5Kw (the max allowed). Possible (yes), Probable (not)
So good to know, that there is more room for Radio Amateurs pumping up the electro magnetical spectral power densitiy.
If Notupus was a licensed Amateur radio operator, he would not have asked the questions he asked the way he asked.
Even if he was. As davidcoton stated, It would be difficult to make a WiFi transmission comply with a (UK) amateur licence. Holds true for DE.

However. Establishing a long range WIFI link is not about transmit power primarily. Most importantly you have to keep a so called fresnel zone free of all obstacles around the direct line of sight between both radio link antennas.

Notupus
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Re: Raspberry Pi 4 External Wifi Antenna

Sun May 31, 2020 9:11 am

So a few months have passed and I got an update, I got a SY call sign in Greece, I am not licenced to transmit in some frequencies but not above 440 MHz see 21.1 on Β-1969/2-9-2011. So basically, just use an adapter and it will work. Since the adapter is licenced not me so I don't have to supervise it.
wolf.z wrote: Most importantly you have to keep a so called fresnel zone free of all obstacles around the direct line of sight between both radio link antennas.
I think it will work since I have line of sight that I tested with some binoculars
wolf.z wrote: Where did you find the spec saying Pi4B has 31dBm transmit power?
I found out of the 31.00 dBm on the pi using RaspAp(Wrong method but still I'm not great at linux but improving)

I think it will since I have line of sight that I tested with some binoculars
I've made 2 Yagi antennas for 2.4GHz in other to do this. I will test it sometime in the summer. Once I can safely go there.

jimmont
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Re: Raspberry Pi 4 External Wifi Antenna

Thu Mar 04, 2021 6:21 am

HOWTO and detailed comparisons adding an external antenna to the RPi4
https://www.youtube.com/watch?v=MTwWnZG8wUY

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davidcoton
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Re: Raspberry Pi 4 External Wifi Antenna

Thu Mar 04, 2021 10:09 am

jimmont wrote:
Thu Mar 04, 2021 6:21 am
HOWTO and detailed comparisons adding an external antenna to the RPi4
https://www.youtube.com/watch?v=MTwWnZG8wUY
Be aware that this will invalidate the RPi WiFi type approval, is therefore illegal in many jurisdictions, and could result in a prosecution.
Location: 345th cell on the right of the 210th row of L2 cache

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sayhello
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Re: Raspberry Pi 4 External Wifi Antenna

Sun Apr 04, 2021 11:32 am

hello dear fellow pi experts, :)

many thanks for this interesting thread. It is very interesting

i have done some search on the forum for topics like this and found only a few that cover the topic antenna etc.

eg how to improve wifi signal
viewtopic.php?f=63&t=306262&p=1832160&h ... a#p1832160

you all share great ideas and thoughts here- so i am glad that i stumbled here over this thread
many thanks for raising these topics here in this thread


Notupus wrote:
The Raspberry Pi 4 apparently has a transmit power of 31.00 dBm which could be used for long range WiFi using a directional antenna.
So in order to add a connector on the RPi 4 what would I need to buy and do?
interesting. I wonder where you have found the spec saying Pi4B has 31dBm transmit power?

davidcoton wrote:
All forgetting one thing. And it's something not generally known. If Notupus is a licensed Amateur radio operator. He could go on channel 1 (2.4GHz) setup a MESH node and transmit 1.5Kw (the max allowed). Possible (yes), Probable (not)
All of the above would require modification of the PI, and he would be responsible for everything being in compliance to license.
I always thought the antenna on PI's since the 3 was inadequate. Diversity antenna systems have always been the norm when you want to hear and be heard. The best way to do it would be to separate the 2.4 and 5GHz as two different paths. Allowing specially tuned antenna's (directional opt).
agreed - this is a very intersting thread - with relations to pi3 setup and threads and an interesting topic.


many thanks for all your ideas, thoughts and the insights in this topic.


cheers :)
say
Last edited by sayhello on Mon Apr 05, 2021 12:19 am, edited 1 time in total.

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davidcoton
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Re: Raspberry Pi 4 External Wifi Antenna

Sun Apr 04, 2021 3:49 pm

sayhello wrote:
Sun Apr 04, 2021 11:32 am
davidcoton wrote:
All forgetting one thing. And it's something not generally known. If Notupus is a licensed Amateur radio operator. He could go on channel 1 (2.4GHz) setup a MESH node and transmit 1.5Kw (the max allowed). Possible (yes), Probable (not)
All of the above would require modification of the PI, and he would be responsible for everything being in compliance to license.
I always thought the antenna on PI's since the 3 was inadequate. Diversity antenna systems have always been the norm when you want to hear and be heard. The best way to do it would be to separate the 2.4 and 5GHz as two different paths. Allowing specially tuned antenna's (directional opt).
davidcoton said no such thing. I replied to that, saying:
It would be difficult to make a WiFi transmission comply with a (UK) amateur licence.
Note also that power limits and frequency allocations in Amateur licences vary from country to country.
Please take more care about attributing quotes, and heed the warnings already given about the validity of the advice you quote.
Location: 345th cell on the right of the 210th row of L2 cache

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sayhello
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Re: Raspberry Pi 4 External Wifi Antenna

Sun Apr 04, 2021 6:35 pm

hello again

first of all - a big big sorry bout the wrong citation - i do now want to bring anybody into

a. trouble nor want to
b. infringe any board rules nor want to
c. encourage anybody to work against the rules and legal setup of telecommunication


a big big sorry - if i did some mistakes.


above all: i love this thread for the open disscussion of the options we have with raspberry Pi 4

have a great day and blessings

greetings

say hello to all of you :)

emma1997
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Re: Raspberry Pi 4 External Wifi Antenna

Tue Apr 06, 2021 11:34 pm

Yes, 30dbm is silly. Considering the corners cut on Pi's WIFI antenna circuit IMO it would be a miracle to manage one tenth that.

I also agree with davidcoton that even a ham license would not help for WIFI. Modulation, duty cycle, data protocol, etc just do not allow for it in any country I'm familiar with. Definitely not in US.

However it's amazing what can be accomplished by locating Pi in proximity to the proper metal objects or wires.

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Imperf3kt
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Re: Raspberry Pi 4 External Wifi Antenna

Wed Apr 07, 2021 3:22 am

There's always wok-fi, though in my experience the Pi wifi works fine without additional cooking utensils.
55:55:44:44:4C
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