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Topic: nrf24l01+ pa lna having to touch antenna (Read 5591 times) previous topic - next topic


Jan 23, 2018, 02:32 am Last Edit: Jan 23, 2018, 02:35 am by MarkT
Yes, I suspect a mismatched antenna - alas checking matching at microwave frequencies requires specialist
test gear (VSWR meter).

The ground-plane or ground radials have a strong influence on tuning - normally for good
behaviour of a simple quarterwave antenna a set of 1/4 wave radial wires pointing downwards in a cone
works reasonably (quarter wave radials in a plane push the radiation pattern upwards, unlike a theoretical
infinite groundplane).

So experimenting with the ground part of the antenna is worth perservering with.  For repeatable measurements
you really need to be outside well away from obstructions and high above the ground, on in an RF test
chamber.  Also be aware of overloading the receiver by being too close, sometimes there's a minimum
range as well as a maximum, but we're not really in that league with these transceivers I think.

[ Oh, the other thing, at 2.4GHz the attentuation rate in cheap thin coax is very high, you can throw
away all your extra power if driving 3m of random unbranded SMA cable - use only short runs and
only high quality cable if you have to ]
[ I DO NOT respond to personal messages, I WILL delete them unread, use the forum please ]


Jan 23, 2018, 04:42 am Last Edit: Jan 23, 2018, 04:43 am by Grumpy_Mike
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on in an RF test chamber.
My son works at a place where they were having an RF test chamber built. The results were awful causing many head scratching. Eventually it was discovered that the carpet fitter had laid anti static carpet, just like he had done in the rest of the labs. No one had told him any different.  :smiley-red:  


My take on the problem is the amplifier is oscillating because the input is picking up the output. The finger on the antenna stops the feedback. P..s poor design.



Since this forum appears on first page of Google I'll add my two cents.
I follwed this guide https://blog.blackoise.de/2016/02/fixing-your-cheap-nrf24l01-palna-module/ and got it working with the stock antenna.
The two things I did were:
  • cover the module with tinfoil
  • use an external power supply - the Arduino can't provide enough current

Now it works, though I achieved a best of 300m in open line of sight. I didn't experimented with the radio channel, but at least it works.


use an external power supply - the Arduino can't provide enough current
Common blunder is to expect the Arduino to "provide" current.

The problem is it has a regulator - of sorts -  on board and this part of the design suggests to rank novices that you can use the 5 V pin as a source of 5 V for other modules when you power it from "Vin" or the "barrel jack".

In short, you can not!  :smiley-eek:   Simple as that.


Jan 06, 2020, 01:51 am Last Edit: Jan 06, 2020, 02:12 am by alpakturk
Having this exact same problem in 01/2020 and I was thinking that I am the only one. So weird that I need to keep touching the module. I found out that touching only one specific side of the nrf24 is enough. I have no idea why does it happen but I'll try to update when I find someting.

Edit: Removing the antenna indeed working well.


Are you using the + version of the NRF.
How close have you got the units when you do your testing?

Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....


I have the same exact issues with the nRF24L01+PA+LNA boards from Amazon. I purchased from two different vendors and experienced the same issue.

Amazon Link: Longrunner
Amazon Link: MakerFocus

My application is a custom car RC remote with my own circuit board design using an arduino nano schematic. I've got 3.3V power from an HT7333A and the nRF24L01+PA+LNA is sodered directly to my PCB. And yet with all that, I still had the issue with touching the antenna block. Finally, I soldered a 3-4inch long wire from the underside of the SMA block and curled it up into my RC remote housing. And now it seems to work with my prototype car, where the radio is in an anti-static bag with the antenna poking out.

I just wish there was a better way to reliably just purchase a radio with long range that just works without all these blind trial and error experiments...

I was thinking of giving these a try. Anybody have any luck with these 2300m units? 

Amazon Link: MakerFocus 2300m

Also considering these with an IPX antenna.

Amazon Link: MakerFocus 1100m IPX


I spent some time playing with these modules, and the most reliable way i got these (nrf24l01+pa+lna) working was by adding a 10nf ceramic cap in between pins CE and CSN, then attaching a wire to the antenna connector and keeping it connected to my hand. This may seem stupid but after a lot of unskilled testing, this way turned out to work the best.

The problem seems to be only in the transmitting part, receiving works just fine without touching anything, except providing sufficient and stable power of course.

I even made a custom pair of reveiving/transmitting antennas for this purpose.

Tested 7 different modules, 2 + 2 + 3 from different e-bay sellers.

My tests included:

  • Providing 3V3 at 20A max current + different power sources - batteries/dc-dc converters
  • Adding caps on power rails
  • Trying different antennas - stock ones, other pre-made, and also home-made
  • Shielding the module
  • Shielding connection wires
  • Resistors and caps on SPI pins
  • Whole thing in a shielded case
  • Different sketches
  • Changing geographical location
  • Switching WiFi off (why not..)

If it is a bad board design, how could it be improved to fix the issue?

I am not into radio communication, RF stuff or anything specific in that topic, only made a few radio transmitters and receivers including antennas found on the internet.
I can't figure out what is the problem in this case, any ideas would be appreciated, to finally solve the mystery.

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