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Using Arduino => General Electronics => Topic started by: batata004 on Feb 25, 2016, 11:54 pm

Title: nrf24l01+ pa lna having to touch antenna
Post by: batata004 on Feb 25, 2016, 11:54 pm
Hi,

I bought a more powerful nrf24l01+ with PA and LNA to get better range but it's much worst than my normal nrf24l01+. After playing around with it I discovered that when I touch the antenna or the header of the pins and keep my finger there the transmitter works really great but if I remove my finger the modules works like crap.

How can I solve this problem?
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: aarg on Feb 26, 2016, 03:06 am
Provide a link to the device please?
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: batata004 on Feb 26, 2016, 07:37 pm
@aarg here: http://produto.mercadolivre.com.br/MLB-696728336-radio-nrf24l01-24ghz-pa-lna-wireless-1000m-arduino-pic-_JM
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: jremington on Feb 26, 2016, 08:52 pm
There are several possibilities, including

1. The antenna is not properly connected, and you are acting as an antenna when you touch the module

2. The high power module is overloading the receiver, and when you touch it you are "shorting" the antenna to ground.

Are the transmitter and receiver modules close together during your tests? If so, move them far apart and test again.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: 6v6gt on Feb 27, 2016, 09:59 am
This reminds me of my ultimately successful attempts to get two of these devices working together. My original prototype with a simple nRF24L01+ module worked fine (apart from the range). When I upgraded to the nRF24L01+PA+LNA - PA-IPX module the one I was using as transmitter exhibited the same problems you have described. Some of the things which helped, but I cannot now say which I finally used:

1. Adding an explicit radio.powerUp() statement before transmitting ( I was using the maniac-bug library - not necessarily a recommendation)
2. Following some of the advice in  http://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo
3. Adding a high value capacitor on the power leads to the module.
4. ditto a low value capacitor
5. If the antenna was bent at 90 degrees, it would perform better.
6. If the radio module was in an antistatic bag with a hole cut for the antenna to protrude out, it had a beneficial effect (although the scientific basis is probably not strong, maybe some mild screening)
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: aarg on Feb 27, 2016, 12:27 pm
Also, what voltage are you running it on, and which Arduino? How is it powered?
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: MarkT on Feb 28, 2016, 01:24 am
Tighten up the aerial, maybe its loose, so that touching makes better contact?
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: aarg on Feb 28, 2016, 01:37 am
I would look closely at the soldering on the SMA connector (well, everywhere if that doesn't turn up anything). Sometimes solder breaks can be nearly invisible, so you can try to reflow it.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: batata004 on Mar 01, 2016, 01:43 am
Thank you all, I did everything you said, added 2 capacitors, made a hole in the antistatic bag... everything you told me. And I still have the same problem. I saw a post on the internet of a guy who used aluminum foil all around the module and IT WORKED! But it's not reliable, sometimes it works sometimes all connections fail.

I have no idea why aluminum foil helped but it's not reliable, maybe I should touch the foil in some specific part of the module? Should I ground the foil?
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: jremington on Mar 01, 2016, 01:58 am
I would throw the modules away and start over.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: batata004 on Mar 02, 2016, 02:36 pm
I discovered someting useful: when I detach the antenna everyting works fine! I dont need to touch the module to make it work but I cant get a good range (10m at top). As soon as I put the antenna I realized I need to touch it's base (right after thte gold connector) to make the module work. Any idea how I can make this work?
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: Watcher on Mar 02, 2016, 06:17 pm
I am also straggling with a couple of similar modules...My project works perfect with the low power - non-amplified versions but as soon as i replace one with the powered nrf24 module, the sketch freezes when it tries to transmit.

Touching the module at various points seems to have some kind of effect but I have never managed to get things working. I have tried to remove the antenna, use an attenuator,  aluminum foil shield, moved the module 30-40cm away from the rest of the circuit.

Nothing worked. Decided to order another pair and try again.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: Grumpy_Mike on Mar 02, 2016, 06:57 pm
Quote
I have no idea why aluminum foil helped
The foil acts as a ground plane for the antenna. The foil must be connected to the ground.

The antenna is reflected electrically in the foil to make it double the size and make it a half wavelength long instead of a quarter.

From:- https://en.wikipedia.org/wiki/Ground_plane (https://en.wikipedia.org/wiki/Ground_plane)
(http://forum.arduino.cc/index.php?action=dlattach;topic=382021.0;attach=157174)
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: alsantour on Jan 22, 2018, 01:47 am
In case someone is still looking at this in 2018 (through google as i was) ... i had the same problem, swapping the high power transmitter with the small one would eliminate the problem.

When the high power trasmitter is connected it would seem like it is not transmitting, but then transmit if i touch the antenna or various spots on the board... Removing the antenna would get it to work but not with a good range...

I am using the power regulator breakout board to connect through that to the arduino , so knew it wasnt a 3.3-5v issue, also do not need to add filter capacitor since they are included on the board.

I thought using an anti-static bag with a hole in it is the most ridiculous idea until i tried it and it worked!! I am baffled.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: Grumpy_Mike on Jan 22, 2018, 09:53 am
Quote
swapping the high power transmitter with the small one would eliminate the problem.
But it was not the drop in power that caused it to work. It was the fact that it was a different transmitter with different output characteristics that was a better match to your antenna.

When there is a mismatch between transmitter and antenna impedance you set up standing waves in the lead and this absorbers the power so you were getting less power out of the antenna on your higher power transmitter than the lower power one.

Having a ground plane changes the impedance of the antenna and not only gives you a better match but also a better antenna.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: MarkT on Jan 23, 2018, 02:32 am
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 ]
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: Grumpy_Mike on Jan 23, 2018, 04:42 am
Code: [Select]
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:  
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: Paul_KD7HB on Jan 23, 2018, 05:01 am
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.

Paul
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: SimoneS93 on Dec 06, 2018, 07:03 pm
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/ (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:


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.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: Paul__B on Dec 06, 2018, 10:11 pm
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.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: alpakturk on Jan 06, 2020, 01:51 am
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.
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: TomGeorge on Jan 07, 2020, 09:11 am
Hi,
Are you using the + version of the NRF.
How close have you got the units when you do your testing?

Tom.. :)
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: bigbangus on Jan 13, 2020, 05:58 pm
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 (https://www.amazon.com/Longruner-Transceiver-Antistatic-Compatible-LKY67/dp/B06WLH4ZG6/ref=sr_1_5?keywords=nrf24l01palna&qid=1578934205&sr=8-5)
Amazon Link: MakerFocus (https://www.amazon.com/MakerFocus-NRF24L01-Transceiver-Antistatic-Compatible/dp/B01IK78PQA/ref=sr_1_7?keywords=nrf24l01palna&qid=1578934205&sr=8-7)

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 (https://www.amazon.com/MakerFocus-NRF24L01-Transceiver-Antistatic-Compatible/dp/B07QC1SXJ8/ref=sr_1_7?keywords=nrf24l01palna&qid=1578934205&sr=8-7&th=1)

Also considering these with an IPX antenna.

Amazon Link: MakerFocus 1100m IPX (https://www.amazon.com/MakerFocus-NRF24L01-Transceiver-Antistatic-Compatible/dp/B07GRMJJY5/ref=sr_1_7?keywords=nrf24l01palna&qid=1578934205&sr=8-7&th=1)
Title: Re: nrf24l01+ pa lna having to touch antenna
Post by: Hackerxd on Jan 27, 2020, 08:53 pm
Hi,
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:



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.