NRF24L01 antenna needs

  • I will be assembling my auto-watering garden project soon. My gardens are about 250-300' (90m) from my house and over an embankment that drops about 10', so I don't have actual line of site. I am not sure how the signal waves work, or if this causes me any concern. I am using HiLetgo 2pcs NRF24L01+PA+LNA Wireless Transceiver RF Transceiver Module with SMA Antenna 2.4G 1100m for my HA serial gateway and my sensors are using the standard built in antenna for the NRF24L01 radio. I would like to assemble my sensors prior to the install and want to be sure my sensors and controller have solid connectivity. Does this seem workable, in general, or is it possible I need to have long range antennas on the sensors too?

  • Do you have a spare breadboard at hand? If not, a bunch of Dupont wires should be fine aswell. Build a minimal circuit and go to your garden. Try to connect to the network with different NRF24 modules and see which one works best. Ideally, you would also bring a notebook to read the serial output and play with #define MY_RF24_PA_LEVEL and #define MY_RF24_DATARATE.

    It's hard to tell how well a wireless connection will perform in a specific location, there are just way to many factors - shape of the landscape, obstacles, WIFI networks and other signals, the weather, humidity,... . So it's best if you test this personally. I highly doubt though that you will be able to get 1100m range out of those PA LNA modules. I used them earlier and they didn't reach much further than regular NRF24 modules with PCB antenna and no amplifiers. I've switched to cdebyte E01-ML01DP5 for gateway and repeaters.

    Generally, I think you want to have a sender with a high power amplification (PA), if you want to transmit over a large distance. A high receive sensitivity on the target (gateway / repeater) is of no use, if the transmitted signal is so weak, that it can't even remotely reach it. It would get lost in noise.

    Sure, getting ~90m range out of NRF24 is possible, but RFM69 / 95 is better suited for this.

  • Thank you! I will check your recommendation out and run some field tests.

  • @BearWithBeard if I use the radio you recommend, will it simply replace what I have without any change to sketches and wiring?

  • @mrhutchinsonmn Just replace it. It has the same 8-pin interface as the other ones.

    Please be aware that the E01-ML01DP5 aren't magical bullets either. They allowed me to reduce the amount of repeaters in our house from one on every floor to one on every second floor (steel reinforced concrete ceilings), but the advertised 2500m range is unrealistic in real world scenarios. Their biggest plus for me are the improved reliability and stability they provide compared to cheap amplified modules, especially at high PA levels.

    BTW - I just saw that they are selling this module for 2,76 EUR / 2.92 USD in one of their other stores in the upcoming sale event, starting on monday:

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