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Trying to transmit (and succeeding) in the ISM BWs at 315 and 433 MHz using a 3.3V radio transmitter IC + PCB trace antenna.

Current setup: separate boards for each one of the two ISM BWs; the antenna is adapted by a different set of capacitors to the 315 or 434 MHz BWs respectively, and fed 3.3V through a different value inductor.

Current goal: have just one PCB manufactured instead of two and a way to switch between the two adaptations of the same PCB trace antenna, or any other practical way to have only one PCB for both BWs and some sort of antennas (external ?) that I can quickly solder / thread in, reflash the device and use it in the other BW. Doable ?

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  • \$\begingroup\$ We do this at work so it should definitely be possible, but I don't know the details. But you left a part out: What's your transmitter IC? \$\endgroup\$
    – pipe
    Commented Jan 31, 2023 at 0:47
  • \$\begingroup\$ @pipe this one - mouser.com/datasheet/2/256/MAX41460-1504638.pdf \$\endgroup\$
    – kellogs
    Commented Jan 31, 2023 at 0:49

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There are quite many RF switch ICs. One example is QPC7512 5M-3.3G RF Switch. This chip is for CCTV applications, thus covering your frequency range. If your RF power is small, you can use this.

enter image description here

When choosing such kind of ICs, you need to check whether it's reflective or non-reflective for the off-path. If you're using this kind of chip just between power amp and antenna, it becomes more important.

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  • \$\begingroup\$ Could be the way forward! One thing I do not like about it - 12 pin QFN - not that easy for me to solder correctly each time. Price could be a bit lower too. Main thing is - how do I use it ? the MAX radio transmitter chip has some 500-ish ohm output impedance, i guess I would have to ditch current PCB trace antenna, adapt the output to 50 ohm antennas and have two of those, external, one for each BW ? \$\endgroup\$
    – kellogs
    Commented Jan 31, 2023 at 17:48
  • \$\begingroup\$ If your MAX-xx transmitter chip has ~500 ohms output impedance, it's probably not intended to use with antenna. You may need a power amplifier chip. With this switch chip put amp between RFCommon and Antenna. To get specific help, you would better to post your circuit details. With general question, only general answer can be get. \$\endgroup\$
    – PCBCrew Engineer
    Commented Jan 31, 2023 at 19:29

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