Bottom Line: I tested maximum line-of-site range with an NRF24L01+ and a 433 MHz transceiver that I’ll be using from some Arduino and Raspberry Pi projects.

I’m learning some basic home automation stuff with Arduino and Raspberry Pi, and I decided to try out some ways to do things wirelessly. I’ve used the affordable HC05 Bluetooth module for a few small projects, and it worked well, but its range is somewhat limited. Instead, I wanted to try out two even more affordable options that might get me a little extra range: a 433 MHz RF module, and the venerable NRF24L01+. Additionally, I tried adding an antenna to the RF module to see if that would help and a couple different models (e.g. one with an antenna) and settings on the NRF24L01+ to see if that would change things.

For the test, I made a sketch that would continuously send a signal to toggle an LED light on and off once per second on a “client” (an atmega328p on a breadboard). After I made sure they worked well at close range, I took them out to my front yard, where I’m lucky enough to have a fairly long straight road. I set the Arduino in my front yard and carried the “client” with me, watching the LED. I considered the maximum range to be the farthest point with a clear line of sight that I would pretty consistently get 10 / 10 toggles transmitted. Then, I marked the spot on Google Maps on my iPhone, and afterwards I used Google Earth to find the distances.

433 MHZ RF Module

Here’s the RF module I used.

I wanted to make sure that my results were absolutely maximal, so I used 6 brand new batteries to ensure my voltage going to the RF module was not an issue. I measured the input voltage at 9.54V.

Without an antenna, my range was about 47 feet (~14 meters) — not bad for such a cheap device! Then I read a few threads on how to make an 1/4 wavelength antenna and made one out of 22 gauge wire (17.4 cm to the bend where I soldered it in). I was impressed by the results — it improved the range by over 200% to 102 feet (31 meters)!

For anyone interested, here is the code I used for the Arduino. Unfortunately I can’t find where I put the code for the client, but it was something just as simple, almost directly copied from the RC-Switch examples.

    RC-Switch library:

#define RF_DATA_PIN 10
#define LED_PIN 13

#include <RCSwitch.h>
RCSwitch mySwitch = RCSwitch();

void setup() {
    pinMode(LED_PIN, OUTPUT);



void loop() {
    mySwitch.send(1234567890, 24);
    mySwitch.send(0987654321, 24);


For these tests, I was using this excellent RF24 Library as it’s still being maintained and includes Raspberry Pi code as well as Arduino code. In preliminary testing around the house, I’d found that setting radio.setPALevel(RF24_PA_MAX) and radio.setDataRate(RF24_250KBPS) made a tremendous difference in the range — the results I’m presenting below are with these settings.

For the NRF24L01+, I started out with this basic model, because it is so incredibly cheap, and it has its pinout printed right on the board. With the right settings, I was blown away by its range! I got a full 384 ft (117 meters).

Next, I tried this model, which is a little more expensive but has an antenna and advertises a very long range. Note that I only use one of these antenna-bearing models for this test. This was in part because I didn’t want to buy two without knowing how well they worked, and in part because I plan on only having one for my home automation “server” and using the smaller, cheaper antenna-less modules for various clients around the house. Using the model with the antenna, I was surprised to get a full 826 feet (251 meters) of range with good reliability, and up to 921 feet (280 meters) with at least half of the toggles transmitting properly.

Here’s the code I used for the NRF24L01+ tests, which is directly taken from the RF24 examples. For the “client,” I think I just had to change the bool radioNumber = 1 and bool role = 1; to ``.

#define LEDPIN 3
#include <SPI.h>
#include "RF24.h"
#include <printf.h>

/****************** User Config ***************************/
/***      Set this radio as radio number 0 or 1         ***/
bool radioNumber = 1;

/* Hardware configuration: Set up nRF24L01 radio on SPI bus plus pins 7 & 8 */
RF24 radio(7,8);

byte addresses[][6] = {"1Node","2Node"};

// Used to control whether this node is sending or receiving
bool role = 1;

void setup() {

    pinMode(LEDPIN, OUTPUT);

    Serial.println(F("*** PRESS 'T' to begin transmitting to the other node"));



    // Open a writing and reading pipe on each radio, with opposite addresses

    // Start the radio listening for data

void loop() {

/****************** Ping Out Role ***************************/
if (role == 1)  {


    Serial.println(F("Now sending"));

    unsigned long time = micros();
        if (!radio.write( &time, sizeof(unsigned long) )){

    radio.startListening();                                    // Now, continue listening

    unsigned long started_waiting_at = micros();               // Set up a timeout period, get the current microseconds
    boolean timeout = false;                                   // Set up a variable to indicate if a response was received or not

    while ( ! radio.available() ){                             // While nothing is received
        if (micros() - started_waiting_at > 200000 ){            // If waited longer than 200ms, indicate timeout and exit while loop
            timeout = true;

    if ( timeout ){                                             // Describe the results
        Serial.println(F("Failed, response timed out."));
        unsigned long got_time;                                 // Grab the response, compare, and send to debugging spew &got_time, sizeof(unsigned long) );
        unsigned long time = micros();

        // Spew it
        Serial.print(F("Sent "));
        Serial.print(F(", Got response "));
        Serial.print(F(", Round-trip delay "));
        Serial.println(F(" microseconds"));

        digitalWrite(LEDPIN, HIGH);
        digitalWrite(LEDPIN, LOW);


    // Try again 1s later

/****************** Pong Back Role ***************************/

    if ( role == 0 )
    unsigned long got_time;

    if( radio.available()){
                                                                    // Variable for the received timestamp
        while (radio.available()) {                                   // While there is data ready &got_time, sizeof(unsigned long) );             // Get the payload

        radio.stopListening();                                        // First, stop listening so we can talk
        radio.write( &got_time, sizeof(unsigned long) );              // Send the final one back.
        radio.startListening();                                       // Now, resume listening so we catch the next packets.
        Serial.print(F("Sent response "));

} // Loop

So in summary, here were my results:

Module Range without antenna Range with antenna
433 MHz RF 47 ft 102 ft
NRF24L01+ 384 ft 826 ft