I have been playing with simple transmission and reception of a 12 byte ASCII message between two arduino nanos. I have been using a 433 MHz receiver/transmitter pair with the VirtualWire library, with some success.
I chose the 433 MHz units for their simplicity and their low price tag. My research before purchasing them, was that these modules would be able to provide line of sight range of 500m. The simplest recommended antenna length is ~17.3 cm of any smallish wire. I soldered (to both TX and RX ) and cut to length a bit of solid wire separated from some CAT5 cable I had.
I created a simple transmitter sketch to repeatedly send the same message. I have the receiver constantly listening and blinking the onboard led each time a message via VirtualWire is received. Everything works well and quite reliably in my home office.
I took both units outside for some line of sight range testing. I placed the transmitter on a small outdoor table about 2 ft tall. I carried the receiver (taking care to hold it away from my body as much as possible) away from the transmitter watching the LED blink. The LED consistently stops blinking about 120ft/~38m from the transmitter.
This was quite disappointing. I'm constructing a moxon antenna for directional use, but I am concerned there is something more basic I'm missing here.
There are numerous results on google and youtube of people getting 100, 200, or 300m with a simple length of antenna wire.
I've tried increasing the voltage to the transmitter from 5v to 8v with no change in range. I've raised and lowered the VirtualWire bitrate from 300bps to 2000bps with no change. I've swapped completely different branded RX and TX modules with no improvement.
I love the low price and simple nature of these modules, but clearly I could use some expert advice.
Thanks for any help you can provide.