A Bluetooth antenna is pretty easy to find and purchase, and many designs (like the Adafruit breakout we'll be using in the simpler version of the core device build) use an antenna printed on the PCB. A 433MHz antenna is even easier, as it is an amateur radio band in addition to being in the ISM band. However, purchasing an antenna is not always the right move, since they can be simple and inexpensive to build.

I plan to try a commercial 1/4 wave monopole, a homemade coil loaded dipole, and possibly other DIY designs for the 433MHz antenna. For the Bluetooth antenna, I'm going to initially try a printed [on the PCB] antenna, but may switch to an external if the range is terrible.