Nrf24l01 with router antenna

  • Hardware Contributor

    Hi all, I tried to found a answer to this question, but didn't found it!

    Can a Nrf24l01 with external antenna be used with a 2.4 wifi antena?

    I have one like this around:


    Thank you!

  • @soloam from my experience NRF24L01 PA LNA has SMA connector and typical router antennas have RP-SMA connector. The difference between them is that one of them has center pin on female and other on male side. I had to resolder connector from a spare PCI wi-fi card to connect router antenna. For next gateway I want to try this module with IPX connector you will ned to buy a "pigtail" to connect it to standard antenna, but in my opinion it is more useful if you need to mount antenna outside of some sort of case for better receiving.

  • This post is deleted!

  • Mod

    note that by changing the antenna to higher gain, you will likely need to lower the TX power of the nrf to stay within legal limits (depending on local legislation).

  • Hardware Contributor

    I tried and the results are as different as nigh and day. The coverage as improved drastically! I think that I still have a power issue on the gateway, the power source is not very good, but I ordered a new charger with good ratings, and I assume that this will solve the problem!

    On the subject of the antenna, I have to make a reliable test, but so far the results where more than great...

  • @Soloam , are you using an LNA version of the nRF24L01? did you attach the antenna to the receiver or the sender? could you say a bit more about how your range increased? thanks!

  • Hardware Contributor

    Hello, yes I'm using the LNA version, and at the moment is attached to the gateway.

    According to range, I did not make test, what improved drastically was the reliability! No missed ack, all on the first try. And before I had a lot of problems with ack.

    I don't think that you need something like this, that said, I ordered a new antenna, because I think that I had a bad unit.

    I think that a solution like this might be good to use outside, where range is a must, but some tests have to be done to ensure that it works.

    In my particular case, that the main issue was lost ack, it worked great.

    Thank you

  • @soloam Before the regulations get quoted over power emissions, I suspect you are possibly misinterpreting the results.
    As is too often the case nowadays, what an antenna contributes unfortunately tends to focus on preconceptions of increased power output, rather than the converse effect of increased reception sensitivity. With chip or PCB antennae they are a physical compromise to save space, and by default will never perform as well as a traditional antenna.
    Increasing sensitivity at the Gateway should in principle allow you to dial down power output at the nodes, changing the antennae on the nodes should allow you to dial down power output at both the nodes and the Gateway while still maintaining reliable communication...

  • Hero Member

    I recall reading a calculation which suggested that the LNA+PA version of the nrF24L01+ would not have a huge increase in range for a two-way connection with a regular transceiver; mainly because the receive side would not be much enhanced after SNR was taken into account (apparently the LNA was not that low noise, as the limiting factor for receiving). For one-way transmission from the PA unit or two way between two LNA+PA units, the improvement was much better . Was that post here?

    Anyway, a higher gain antenna should help, as it increases signal strength and SNR in both directions. But is it true that higher gain is (almost??) always at the expense of a narrower emission pattern (kinda like using mirrors and lenses with a flashlight - the same power can be emitted weakly in all directions, or more strongly the smaller the focused beam)? And likewise for receive. For the example antenna in this thread, I believe the gain pattern is sort of toroidal - best at right angles to the antenna, less than unity along the axis. To get 9 db this would need to be a fairly flattened toroid (a stepped-on bagel). So in general, antenna gain is not an unambiguous "win", but rather involves a tradeoff which may or may not be worthwhile for a given system.

    That can work well for a ranch style house which is mostly 2 dimensional, but for a multi story house the low transmit/receive gain along the antenna axis sometimes needs to be taken into account.

  • Mod

    It all depends. You can make a directional antenna to go farther in a specific direction with less power or use a 360° one to have an all around coverage but with shorter range and still need to use higher power. Of course a PA lna and a regular module would not be as good as 2 PA lna, but it still could work better than 2 regular ones.

  • @gohan said in Nrf24l01 with router antenna:

    You can make a directional antenna to go farther in a specific direction with less power.....

    Transmission power input can indeed be reduced with any higher gain antenna, even going from a coiled 1/4 to a Dipole can reduce power input to advantage. However, directional and omni-directional arrangements need not be mutually exclusive.
    In the majority of cases omni-directional antennae are simple to make and quite adequate for most case uses, particularly for sub GHz.
    In the vast majority of arrangements, the gateway will be physically central to the nodes so has to be omni-directional.
    It is at the radial nodes where a directional antenna can provide benefits of larger signal or reduced power input, as it only has one direction to aim at, the Gateway.
    A directional antenna is in simplistic terms an omni-directional antenna with reflectors and directors, but it is the reflector which is crucial. Mounting an omni-directional with a metal reflective surface behind it will squeeze the radiation and receive lobe in the opposite direction, be it the metal siding on a shed, a biscuit tin lid, or a simple trough reflector. Easy enough to make without resorting to higher battery consumption...
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