The antenna diversity scheme on the ATmega128RFA1 uses two antennas to select the most reliable RF signal path. This is done by the radio transceiver during preamble field search without interaction of the application software. Both antennas should be carefully separated from each other to ensure highly independent receive signals. The radio transceiver of the ATmega128RFA1 can be also used with an external RF front-end to increase the link budget or to control external RF switches. When using an external RF front-end, separate control pins on the ATmega128RFA1 automatically switch the front-end between the receive and transmit states. Again, this works without any interaction with the application software.