Do I need to use special wire or a proper aerial for these devices. At the moment I am just using some hook up wire and it's working with the rx sitting under my desk on top of the PC case and the tx about 10 m away outside. If I have the tx close to the house, kind of in a corner the reception has been lost a couple of times. In the middle of the garden it seems fine.
433 MHz Tx/Rx
- Thread starter Kiwi Bruv
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Stan is better qualified to answer this than me but ordinary hookup wire should be OK. The critical thing is the length. I don't know the correct length off the top my head but it is related to the module frequency. The spec sheet of the module should tell you the ideal length. It is possible to buy "proper" aerials but they are VERY expensive and don't always work as well as a good home made length of wire anyway.
The piece of wire should be just fine. If you want to get technical, 1/4 wavelength would give you good performance. To get the length, you divide 234/Fmhz. This will give you the length in feet. I dont know the one for metric.
234/433=~6.5 inches (6.484988 inches to be exact). Half wave would be about 13 inches minus a few thousandths. Half wave=better than 1/4 wave. 25.9 inches will give full wave, even better performance, but it's gettin kinda long now.
Unless you have pretty specialized equipment, I wouldn't bother trying to get it exact to what it's supposed to be. Using 6.5, 13, and 26 inches respectively should be close enough.
The other thing is that as radio waves get higher in frequency, they get ALOT more finicky. The US navy communicates with it's submarines using frequencies so low thier wavelengths are measured in tens or hundreds of miles. These penetrate the earth and actually reverberate off the molten core and back out to the subs.
Good luck getting a signal of a few tens of gigaherz to even go through a tree or cloud, let alone a wall. It's all a compromise. 433 mhz isn't too bad, but it can be scattered and blocked depending on things like the material in it's surroundings, any EM fields, etc. placement can be jsut as important as the antenna or output power itself!
--Andy P
234/433=~6.5 inches (6.484988 inches to be exact). Half wave would be about 13 inches minus a few thousandths. Half wave=better than 1/4 wave. 25.9 inches will give full wave, even better performance, but it's gettin kinda long now.
Unless you have pretty specialized equipment, I wouldn't bother trying to get it exact to what it's supposed to be. Using 6.5, 13, and 26 inches respectively should be close enough.
The other thing is that as radio waves get higher in frequency, they get ALOT more finicky. The US navy communicates with it's submarines using frequencies so low thier wavelengths are measured in tens or hundreds of miles. These penetrate the earth and actually reverberate off the molten core and back out to the subs.
Good luck getting a signal of a few tens of gigaherz to even go through a tree or cloud, let alone a wall. It's all a compromise. 433 mhz isn't too bad, but it can be scattered and blocked depending on things like the material in it's surroundings, any EM fields, etc. placement can be jsut as important as the antenna or output power itself!
--Andy P
Guilty as charged. I've indeed been doing a LOT of 434 work recently, with a SiChip article for November(?) shaping up. Which units are you using - those newer Jaycar ones perhaps? The best quickie antenna is a 1/4 wave whip (hence ~170mm), but it's NOT critical. Far more important is a good unobstructed RF takeoff. I've managed ~1km LOS using the <A href='http://www.picaxe.orcon.net.nz/yagi433.jpg ' Target=_Blank>External Web Link</a>"cotanga" design. RECOMMENDED