BigRedBee worked with our long time partner Gotek7 to create a very small, very thin 433 Mhz FM RF beacon. The goal was to build a transmitter small enough to fit inside a Rolex watch in place of its movement. We chose a flexible film PCB instead of traditional FR4, and a chip antenna to minimize size. We also included a low voltage battery management circuit with hysteresis that shuts down when the battery falls below a specified level, and resumes operation when the battery is fully charged.
Device diameter is 30mm and maximum thickness is 2mm. RF output power can be set to either 0 or +10 dBm. Transmit parameters are user selectable using a custom programming jig with pogo pins that mate to test pads on the back of the board. We chose +0 to further conserve on power. Range was greater than 800m using the very sensitive Compact Pro UHF receiver.