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Antenna for raspberry pi

Posted: Fri Dec 25, 2020 9:31 pm
by itay
Using my RTL-SDR & a raspberry pi I've manager to record & replay a signal thats open our parking gate from my apartment window.

I used the RTL-SDR v3 from my laptop just to record and then I played the recorded signal directly from a raspberry pi using rpitx and multiple jumper cables.

While it works pretty nice I need to adjust the antenna a little bit in order to make it work, and I suspect that the problem is the antenna: Although it is in the correct length, I used multiple jumper cables connect one to each other and I suspect it doesn't give the best result.

I've seen some tutorials on the blog about multiple types of antenna, but didn't understand which one would do the best for me, can you give me some suggestions for that?
I creating a 433 mhz signal using my pi toward the parking gates which is probably ~15M away from my window.
any suggestions?

Re: Antenna for raspberry pi

Posted: Sat Jan 02, 2021 2:36 am
by Aussie Susan
How are you using the RPi to generate the 433MHz signal?
As for the antenna, in general the lead between the Tx device and the antenna can be just about anything and any length (up to a point) AS LONG AS it has the right impedance. For example, if you are using a Tx device that expects a 50Ohm load then there are lots of coax cables out there that could be used. The antenna itself must also match impedance and therefore must will depend on what impedance it was designed to have.
If the impedances are NOT matched then you will get reflections from the points of mis-match and that all means signal that is lost to the antenna. There are ways to get around this (baluns etc. to match different impedances) but you will need to tell us a lot more about the system you are using.