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Full Version: 433 MHz max range
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Hi guys - what an amazing project you have here. Am pretty keen on building one - and will post a few questions. 

What is the max range of the TX to RX unit. I would plan (in the long term) to set up multiple TXs for soil moisture monitoring in my vineyard, and would need at least 200 to ideally 300m. I can do true line of sight and no other houses in the area. Has anyone achieved this ? , is it possible without changing the radio module ?

Any thoughts appreciated
Hi coupe pete,

Welcome to the forum, and thank you for your words about the WeatherDuino project.

I think that is hard to say what is the maximum range for having a reliable link, there are many factors which can affect the signal. It's better not expect 200 to 300 meters, under very good conditions (line of sight, no concrete walls between, and zones without to much electrical noise) the range can even be greater, however its better not count on it.
There are 433Mhz amplifiers that could be attached directly to the RF output of the transmitter, some are quite powerfull, up to 500mW, but using them may not be legal.
Thanks Werk - sounds like there are solutions that can worked through when the time comes.  First step is to get the basic weather station going so I'll get started on that.
you can use antennas with a little more gain.
Here are some examples:


https://fr.aliexpress.com/item/1-piece-G...0.0.R2Y8aN

https://www.ebay.fr/itm/IMMERSIONRC-433M...2a9a129501

it is much better in terms of range than short antennas. 300m is ambitious with this type of module but not impossible, it depends a lot on the environment.
Hi coupe pete,

and welcome in our forum from me too.

I would not be too afraid of such an impact on the vineyard. I would try to get both antennas, both receiving and transmitting,
to pick up as high as possible above the support devices, so as to minimize disruption the so-called Frennel zone in which the electromagnetic
energy is transmitted:

[Image: 800px-FresnelSVG1.svg.png]

But do not forget that the antenna cable can be the biggest attenuation! I.e so to lift the whole receiving and transmitting unit,
not just the antennas themselves.

Good luck!
[img].https://upload.wikimedia.org/wikipedia/commons/thumb/5/5c/FresnelSVG1.svg/1000px-FresnelSVG1.svg.png[/img]