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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:

back

front

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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 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 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 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 at 3:56
  • That’s not what I asked. I already know about the length requirements and am considering either a half our whole length. The reason my original question asked about twisting the wire on the coil was because I wanted to test the two lengths to see which was sufficient for my needs. The held length on the transmitter gives me a little trouble with an outlet on the porch but otherwise covers the whole house. Perhaps I should have explained that more fully in the question as to not necessitate these follow ups. But I assumed the coil part of my Q would elicit an answer that addressed it. – hepcat72 Jan 22 at 12:43

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