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I have a couple different Bluetooth boards similar to this one I took a photo of. It works fine but I can seem to find any info on if I can hook up an external antenna to it or not?

The documentation doesn't seem to mention it.

I know what the VCC GND TXD AND RXD pins do.

I have successfully used it. Is there a way to hack in an extra antenna?

enter image description here

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  • \$\begingroup\$ Do you have a picture of the other side, I believe the antenna is there.. Perhaps you can rotate and crop the images while you are at it? Optimum width for this site is 630px. \$\endgroup\$
    – jippie
    Sep 22, 2013 at 16:54

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The JY-MCU Blue Tooth module contains a trace antenna on the flip side of the board, the zig-zag trace at the bottom left in this photo:

JY-MCU
(Image source)

While it is conceivable that a skilled person could scrape out the PCB trace leading to the antenna, and solder in an external antenna of just the right wavelength and impedance to work with the radio frequency input/output stage of the device, the odds of any improvement in performance are little to none.

It is also worth noting that integrated Bluetooth devices such as this one are typically not designed with sufficient power headroom in the RF stage to be able to drive a significantly bigger load than the antenna designed into such a board: After all, if the intent of an external antenna is to increase range, that would necessarily translate into either a highly directional signal, or higher radio frequency power.

  • If the project supports investing in a directional antenna, then presumably it will also support a more capable Bluetooth module, for far less money.
  • If the idea is simply to pump more radio power out, that power must come from somewhere, namely the RF output driver, which is unlikely to be capable of this.

It might be a better option to simply choose some other Bluetooth module, one that supports an external antenna out of the box.

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Altering this kind of RF circuit is strictly prohibited by the FCC rules.

The design characteristics are set by the manufacturer to comply with interference reducing regulations for a shared frequency range. unless the manuacturer, under FCC license, supplies an add on antenna kit, any modifications to the power, antenna size, gain, shape, etc, basically anything, is not allowed.

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  • \$\begingroup\$ Im not making a commercial product or some wunderwaffe. It's just modding something to make some new cool stuff. I'll be damned if I am going to let the GOVERNMENT, a group that can't even decided on basic financial needs or commit money toward its own people instead of trillions for bombs, to tell me what I can and can't do in my own house. \$\endgroup\$
    – DotNetRussell
    Sep 23, 2013 at 11:41
  • \$\begingroup\$ i guess, but the air, water, and radio space is not your house. neither the street, the sound level or the internet. all are shared resources and our government steps in to ensure that a single entity doesn't ruin it for everyone. you can have heavy bass music running 24 hours a day, in your house, shaking the walls, if nobody is home next door you're fine. if somebody's bluetooth devices next door just stop working because of the power put out of your antenna, maybe somebody will notice, maybe not. depends on whether your neighbors work for FCC consumer enforcement or not. \$\endgroup\$
    – Andyz Smith
    Sep 23, 2013 at 11:46
  • \$\begingroup\$ While AMRs comment is a little over the top (there are good reasons not to allow people to make 10MW transmitters in their house because it will affect others) I'm not sure this answer is 100% correct either. I live outside the US but if my understanding is correct you can legally alter an antenna system as an an end-user as long as it still falls within FCC limits. \$\endgroup\$
    – PeterJ
    Sep 23, 2013 at 11:52
  • \$\begingroup\$ Guess we'll find out if and when I decide to do work with it. \$\endgroup\$
    – DotNetRussell
    Sep 23, 2013 at 11:53
  • \$\begingroup\$ @PeterJ perhaps, but i'd refer to a recent rulemaking from the FCC regarding consumer level cell phone signal boosters and their accessories The ruling ( part 45. f. ) specifically admonishes consumers from using any other types of accessories ( presumably this includes user enginnered accessories ) that were not specified and tested by the original manufacturer for use in conjunction with a particular product. \$\endgroup\$
    – Andyz Smith
    Sep 23, 2013 at 12:04

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