I have these 433Mhz chips. I already have an antenna on the transmitter chip and it works great. The receiver works too, but you have to be really close to it for it to pick up the signal. I would like to be able to detect state changes from remotes that came with my RF outlets, so I cut a length of wire as an antenna, but the receiver chip doesn’t have an ANT hole like the transmitter does.

Can I twist-tie the antenna to the coil that’s on the chip or else solder it to the chip somewhere? And would doing so give me roughly the same receiving range as the transmitting range I get from the companion transmitters?

Here is a picture of the front and back of one of my receiver chips:



1 Answer 1


Tha small circular solder pad in the lower left corner of your second picture is the antenna connection.

  • Thanks! Is the coil next to that the current antenna?
    – hepcat72
    Jan 21, 2020 at 3:26
  • No, It's for matching the impedance of the antenna to the receiver. It's part of the antenna system, but is not actually an antenna. Search for MX-RM-5V datasheet on Google and you should find more information.
    – SoreHands
    Jan 21, 2020 at 15:39
  • Is there a way to test a length of wire to see if it’s sufficient before I solder it? Like a clip or something so I can make the connection, walk far away with the remote and see if the signal I send gets received? If it doesn’t, I can try a longer wire...
    – hepcat72
    Jan 21, 2020 at 17:38
  • Antennas work best when they are resonant. The simple explanation is they need to be a certain length, or some multiple of that length. The datasheet states the recommended length is 17 cm. Any antenna you connect should be that length or an integer multiple of that length. Random lengths of wire, even if longer may actually work much worse. Also, coiling, bending, or folding the wire will degrade the antenna's performance. Antenna design is a complex and fascinating subject but is rather off-topic this forum so I'm going to refrain from commenting further. Good luck with your project!
    – SoreHands
    Jan 22, 2020 at 3:56
  • 1
    An inferior connection will result in inferior reception. Changing the type of antenna connection changes the operating parameters of the circuit, rendering your test meaningless. For reliable, repeatable results, do it the right way, solder it. It's not like solder is permanent. And if you don't want to solder, you're operating in uncharted territory with unknown parameters and I doubt anyone can predict what results you will see. It may work, it may not. You'll just have to try it and find out.
    – SoreHands
    Jan 23, 2020 at 0:36

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