I have a NRF24L01 model with an included screw-on antenna and apparently also an integrated RF amplifier (something like this, image sourced from eBay seller top_electronic1980). I have a lot of interference where I want to use this chip, and therefore my range with this is not more than a few meters, and even less if there are obstacles such as walls.

enter image description here

How are my chances to modify this device to output drastically more power? It does not need to be portable, so power consumption is not an issue. Also, it can use a highly directional antenna as I want to reach a specific receiver device that I know the approximate location of. I know it operates in the 2.4 GHz frequency band, so maybe something like the WiFi cantenna?

Thank you for your help!

  • 1
    \$\begingroup\$ "How are my chances to modify this device to output drastically more power?" - basically zero. \$\endgroup\$ – Andy aka Oct 14 at 13:20
  • \$\begingroup\$ @Andyaka why exactly is this the case? i am not an expert in rf, so i am interested \$\endgroup\$ – Twometer Oct 14 at 13:27
  • \$\begingroup\$ @Andyaka How would it be with an external amplifier and high gain antenna attached to the nrf's output? \$\endgroup\$ – Twometer Oct 14 at 13:28
  • \$\begingroup\$ Your actual issue is almost certainly misuse such as improper settings or misoperation of a T/R switch, unreasonable expectations (some packets will get through, not all), unsuitable power supply, or a defective module, antenna, or cable. \$\endgroup\$ – Chris Stratton Oct 14 at 13:45
  • \$\begingroup\$ @ChrisStratton When used "normally", the chip works fine for me, and has a long range. I also use my lab bench supply, so I think it should have enough power. But when in the required environment, it has to overpower another transmitter sending to the same target device, and this only works on very short distances for me. Does an external amplifier solve this issue? \$\endgroup\$ – Twometer Oct 14 at 14:03

Without more information(competing signal levels, distance to target, etc) I can't really give specifics. But here goes...

I would first try a good directional antenna.
There are plenty of 2.4Ghz Yagi antenna available, I would try something with a 9dBi to 18dBi gain to start with. Then you'll want a GOOD cable to connect it to your board. This means using something like LMR195/200/400(preferably one of the last two) for the coax, with the appropriate connectors for your fittings. This means at least one male SMA fitting and either a male SMA or N connector depending on what your antenna has.

PLEASE NOTE: Unless your antenna is less than a foot from the board, DO NOT get a cable made from something like RG-58 and I would never use RG-174 except for very short lengths, like 2 or 3 inches. You'll end up with so much cable loss that you will have wasted your money. The good cables are not that much more expensive. I can get a high quality 50ft LMR400 cable for $100 with connectors. BTW, the only way I would have a 50 foot run is if I had an amplifier at the mast head.

If for whatever reason this does not work you'll have to go with an external amplifier. I would mount the amplifier at the antenna to avoid power loss in the cable. And depending on the specific amplifier, you may have to reduce your boards transmitting power.

Hope it helps.

  • \$\begingroup\$ Thank you very much! The competing signal is from a phone sending bluetooth data. My transmitter would be 3-8 meters away. I can mount the antenna very close to the board, that is not a problem. I will try this, but if it does not work, what type of amplifier can I use? I have found some amplifier chips that can operate in this frequency range such as "SKY65016-70LF". The datasheet says they can be used with WiFi, so i think they'll work? \$\endgroup\$ – Twometer Oct 14 at 15:50
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    \$\begingroup\$ I would NOT try to make your own amplifier. Unless you've got L band+(meaning higher than 1.2Ghz) RF experience, building, not using, I can almost guarantee you it won't work. This is NOT something you can just tinker toy and expect it to work. And there is no reason to do it, in this day and age you can get a high quality 1-2W(if not more) amp for less than $150. Sure I might be able to make it work, but I've been working on and building RF equipment for over 30 years, everything from 40M(7Mhz) QRP(low power) rigs to 5Ghz preamps. But I'm sorry if you have to ask, the answer is no... \$\endgroup\$ – GB - AE7OO Oct 14 at 16:22
  • \$\begingroup\$ The biggest problem you'll have is matching the freq. BT is a freq hopping protocol with 79 channels, 1Mhz apart starting at 2402Ghz. \$\endgroup\$ – GB - AE7OO Oct 14 at 16:36
  • \$\begingroup\$ Thanks for all this information, I will definietly try this out. Also thanks for warning me so that I won't waste my money on a DIY amplifier. As for the bluetooth, I was able to interrupt a bluetooth transmission from a short distance, without calculating the exact frequency, but to do more than that I would have to recalculate the hopping table, I think this is possible somehow. \$\endgroup\$ – Twometer Oct 14 at 19:01

How are my chances to modify this device to output drastically more power?

The device is a transceiver and the transmit/receive arbitration circuit is inside the chip and therefore you cannot put an amplifier in the antenna feed (unless you are highly skilled and have access to good equipment) because it'll stop reception of the RF signal.

Plus, adding an amplifier (even if you could) will very likely take it beyond its legal power output rating.

  • \$\begingroup\$ The device only needs to transmit, so I don't need the receive portion of the NRF. \$\endgroup\$ – Twometer Oct 14 at 14:06

You did not specify your requirements, but if you need a low speed, you can use the following tips:

  • Use the lowest speed possible
  • Use the maximum power setting
  • Use the external antenna shown in the pic

Than check how many packets are arrive successfully. If this is 0, you are mostly out of luck, but if it is higher than 0, than you can use a protocol (I think it's even inside the nRF but if not create your own) to resent packages which are unsuccessful (by e.g. using a CRC value). So even though there are lots of obstacles, you (eventually) pass the packages across.

  • \$\begingroup\$ Thank you for the tips, but I already use these settings for my current setup. However, this was mostly trial and error. What exactly does the speed setting do to the transmission power? \$\endgroup\$ – Twometer Oct 14 at 15:51
  • \$\begingroup\$ See e.g. lastminuteengineers.com/nrf24l01-arduino-wireless-communication part lower data rate, fragment: The nRF24L01+ offers highest receiver sensitivity at 250Kbps speed which is -94dBm. However at 2MBps data rate, the receiver sensitivity drops to -82dBm. If you speak this language, you know that the receiver at 250Kbps is nearly 10 times more sensitive than at 2Mbps. That means the receiver can decode a signal that is 10 times weak. \$\endgroup\$ – Michel Keijzers Oct 14 at 15:54
  • \$\begingroup\$ That makes sense now i understand thank you very much for the explanation \$\endgroup\$ – Twometer Oct 14 at 15:57
  • \$\begingroup\$ You are welcome! \$\endgroup\$ – Michel Keijzers Oct 14 at 16:05

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