Boomerang External Antenna

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Important Notice: Using an external antenna voids the FCC modular certification.
Tmote Sky must be recertified by the FCC for each external antenna configuration.

Tmote Sky has two antenna options—and internal antenna built into the module and an external SMA connector for connecting to external antennas. By default, Tmote Sky is shipped with the internal antenna enabled. If an application requires an external antenna or a different directional pattern than the internal antenna, an SMA connector may be installed and an antenna may be connected directly to Tmote Sky’s SMA female connector.

In order to switch between the internal antenna and the SMA connector, the capacitor at C73 must be moved from the two left pads to the two right pads connecting the radio to the SMA connector. This process may be completed quickly with a heat gun and tweezers by sliding the capacitor over to the adjacent pad once the solder begins to melt.


The newer Tmote Sky modules are FCC certified for use with the internal antenna. Because of FCC regulations, these nodes are shipped with metal shields covering the radio circuit. The procedure outlined above can be performed on the newer modules once the RF shield has been removed. The most effective way of removing the shield is to cut away its top with wire cutters, and then bending the walls back and forth until they break away. Performing this procedure will void the warranty.