Adding Kilometers To A Radio Meant Only For Meters

The NRF 24L01+ radio transceiver can be found in a lot of wireless project builds. But it’s only meant to work at a range of a few meters. [Achu Wilson] found that he could greatly extend the range by as much as 2 kilometers. All he needed to do was build this high-gain antenna.

He already had an idea of what he wanted to use the RF link for, so a directional antenna is no a problem. He chose a biquad setup with a back reflector, then used NEC2 to model the design and tweak it for the best performance possible. It only took him about two hours to complete the build, and manages a 10 dB gain. Not bad for some wire and a scrap of sheet meta.

This is the same transceiver chip used in the SNES wireless mod. If only we had a really powerful set of binoculars we could play the extremely long-distance game of Mario Kart we’ve always dreamed about.

25 thoughts on “Adding Kilometers To A Radio Meant Only For Meters

  1. Gotta be careful with these sorts of projects. Many of the violate FCC regulations here in the USA unless you have the proper licensing. I got busted a few years back for an long distance directional wifi cell I built to allow me to use my own internet connection at my workshop four blocks away. (Still have no clue how the FCC found out and busted me, but I suspect buying the parts in Tijuana and bringing them across the border may have had something to do with it….)

    1. That and a local Ham Radio Operator, or Shotwave listener all of a sudden had a new “hash” generator popup near them.

      The FCC also has “listening Stations”, as well as the American Radio Relay League has “Official Observers” who help out the FCC as well.

      Thank you very much, for mentioning what you did Johnny. Many of us Ham Radio enthusiasts totally support home brew anything. However many of the same of us, are also annoyed when people break rules and end up dramatically impacting things they are unaware of.

      1. Agreed. I admit that in my younger years I did some pretty “crazy” hacks. Oddly, until you commented, I had never even considered ham radio operators. I hope I didn’t mess up somebody’s rig in hindsight.

        As for details: there is really no need. I could tell you it was a stormtrooper raid with lots of dudes in sunglasses, but that would be complete bull. Truth be told, the gal that served me the papers was hot as nine hells though…and in order to avoid paying obscenely high fines, I was forced to voluntarily give up quite a bit of my equipment and close my workshop. (I guess they would call it a hackerspace these days, but it was more of a solo gadget garage.)

      2. Yeah the HAM world is full of the kinds of people you give a little authority to and they will rat you out in two seconds. Mostly middle-aged guys who spent their entire lives loving the state, and probably get checks from it too.


  2. i have manny nrf24s, they are useed in manny cheap rc helis and have a range of around 500 meters. maybe they have little amps on board “i dont know” but they have a fairly good range without mods. but how far would one be able to go omni ?

  3. i have used these biquad antennas before for wifi and xbee weather stuff

    they work great … i use a 1 watt wifi card (with packet injection … $30 on amazin!) with a dual bi quad antenna i stuck up on our flag poll and even with the power out i always pick up a good internet connection from somewhere!
    just careful of the noise!

  4. the bi-quad antenna is a well tested and widespread design, and can be simply and easily scaled to the frequency of interest if you know that

    v = f x lambda

    v = speed of light
    f = frequency
    lambda = the wavelength of the wave at that frequency

    If you can’t be bothered modeling with NEC (which is only going to scale the design anyway from baseline dimensions when it models things) substitute your numbers in the above equation to scale accordingly.

    i.e. if you halve the frequency, the dimensions increase by a factor of two.

  5. :) cool project. I dont think you voilate fcc with a higher gain antenna because the limit is on transmission strength, which is still the same.

    can I build this stuff from scrap meta tags too?

  6. Limit is on EIRP. So the antenna gain would affect the limit. You can not have same power Tx with high gain antenna as you can have without an antenna. Atleast, thats how it is in India and I guess worldwide (on 2.4GHz ISM band)

  7. FCC, an most countries regulations put a limit on the Effective Isotropic Radiated Power (EIRP), not on the total transmission power. Meaning that a high gain directional antenna will probably violate local regulations even at very low power.

    For the US you can check this article: about EIRP regulations.

    In Europe, at least here in Spain, we have more tight EIRP constraints. The power limit can be expanded by adquiring a ham radio licence (I guess that’s also true in the US)

    1. True hams in the US can use more power than the unlicensed users. Beyond that we are protected from interference from the unlicensed users, and they have to accept interference from us. Using more power is expensive so most hams rely on antenna gain whenever they can. Distances up to 35 mi 56 km using off the shelf WiFi can be realized I read with careful path selection and gain antennas. The only down side for hams is if we use WiFi on amateur radio allocations using our call signs we are restricted as to what we use it for, no playing music or watching dirty movies. Ironically if we use that same spectrum as unlicensed users we can use it for that.

  8. @Imbroglio LOL Middle age, that’s me, much better than the alternative I say. Not sure what authority I have been given other than the authority to legally transmit in certain bands. Just like copyrights and patents that limited authority is good as the efforts to protect it. Besides that there are many radio services that can suffer interference. Screw up law enforcement there’s hell to pay, worse yet foul up someone’s TV you’re head for the gallows

    1. This reveals a pattern. Every HAM I knew who ever had their call sign as a car tag, or talked of it, would say that the moment you do that, or get an antenna in your house, the complaints from neigbors start rolling in and here come the inspections. I guess it’s tit for tat. If someone transmits something HAMS will go ratting. So it’s only fair that the moment the TV reception is no good the non-HAMs go ratting too. Lovely system of turn in your neigbor we have here.

      1. Imbroglio…. The US has become a nation of me first for a long time now… They forget that the majority of the technological advances we have had came from times when there were fewer restrictions… I.E. Tesla, Edison, etc…. If the FCC in its current state existed when Tesla was around, I don’t think we’d have the radio or AC current…

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