Im working on a DIY project to build a door alarm security system. For this I would be using pro mini’s to trasmit data from door sensors over RF to a Uno acting like a hub. I am using the regular 433Mhz transmitter and receiver.
On breadboard test, I am getting a range of max 20ft. I have soldered a thin copper wire of 17cm as an antenna on both receiver and transmitter. On doing some googling, people claim they get a range of 30-50 meters with a 17cm antenna. And Im struggling to get 20ft at line of sight without interference. In my living room the range dropped to 10ft. I kept the antenna straight up on both receiver and transmitter. My transmitter circuit is using 9v battery and receiver is hooked up to the laptop.
My house is two stories. I want to keep the Uno hub on second floor and all door sensors at first floor. I think if i get 50-60ft range through walls, I would be good to go. How to increase the range? What kind of antenna will help?
Heard 433s doesnt do a good job penitrating walls, but I did get signal through the wall. I am ok using some other RF circuits too like bluetooth/wifi etc. But it should have a good range and should penitrate through walls.
have soldered a thin copper wire of 17cm as an antenna on both receiver and transmitter.
Try placing a conducting sheet, metal foil, or PCB material under the unit. Connect this electrically to the ground of your circuit and do not let it short out any of your circuit.
This is known as a ground plane and it improves a single wire antenna by reflecting the signal and forming a dipole antenna.
no. helical antennas are about more antenna in less space. this requires a compromise away from the direction of more signal strength
433 mhz is also a ham band. it is also known as the 70 CM band. the first step to take is to look up a DIY quarter wave dipole & a half wave dipole.. the simplest practical designs that exist.
but after you upgrade to a pair of HC-12 transceivers. it sounds like you have an RF-433 transmitter & receiver pair, which is one step lower than I would bother with.
They are very directional so the antennas need to be pointing at each other.
They produce circular polarisation radio signals. Where as what you have produces vertical polarisation, so you can't mix them with anything else. Well you can, but if you do you loose half the signal.
A balanced dipole works extremely well, as shown in the following. I get 300 meters range line of sight with this setup. Dipole is about 33 cm from tip to tip, with one inner conductor connected to ANT, the other to GND.
The little spring type helicals are very inefficient and are only useful if you are short of space .
Also, the receiver you are using is a superegen type and these are the worst possible type you could pick as they have the worst sensitivity and the worst immunity to interferance .
If you want to use these cheap OOK radios, at least use the superhet type , which can be identified by having a crystal on the PCB .
these are the worst possible type you could pick as they have the worst sensitivity and the worst immunity to interferance
The superregenerative receiver used in the setup shown in reply #11 works very well, indeed far beyond expectations, and is more than adequate for the job.
Despite the shape those are not actually helical antennas. They are end loaded whips, or simply a quarter wave dipole, like you had with the straight wire. The spring acts as an inductor allowing the resonant frequency to be lower than it otherwise would be for that length of antenna.
@jremington: Cool. Did u test the range indoors? Does it penitrate through walls? I am fine with having a 33cm dipole antenna for the receiver, but I want my transmitter to be compact. Is there a way I can use a hybrid antennas?
