This is the AT86RF212 900 MHz radio peripheral v1.1 for the FreakLabs WSN rapid prototyping MCU boards. It supports the license-free 915 MHz North American band, 868 MHz European band, and the 780 MHz Chinese band. It's supported by the Chibi software stack and the default band can be set in the stack.
900 MHz radios are often preferable to 2.4 GHz radios because there is less crowding in the frequency band and lower frequencies suffer less path loss and attenuation. Hence the range will be greater for the same amount of power between a 900 MHz radio and 2.4 GHz radio.
This board has a FreakLabs universal serial connector that can connect to any FreakLabs MCU board and also comes with either an RP-SMA external antenna connector or a 868/915 MHz SMD antenna. For the 780 MHz band, you'll have to choose the RP-SMA connector and provide your own antenna. Since that band is quite new, supplies are very limited at the moment and I haven't found a good supplier yet.
The antenna options should be found below. The default option is the external RP-SMA antenna since this offers the most flexibility. If no antenna is plugged in, you can still transmit and receive between nodes a fair distance due to the RF leakage and the receiver sensitivity of the chips.
Its also possible to mount an additional 916 (North America) or 868 (Europe) MHz antenna along with the RP-SMA connector. If both antenna options are installed, you'll need to select the default antenna in the drop-down box below. This lets me know where to install the option capacitor/resistor.
A very important thing to note is that this device has an internal power amplifier which can boost the transmit power output up to 10 mW (10 dBm). This is 3-5x the typical 2.4 GHz radio and at 10 mW, the range is quite significant. Although range depends on the surrounding topology, most people are very surprised at how well these radios perform and the distances they can get out of them.
FL-AT86RF212-DEV v1.1 User Guide