Long range radio systems using 900MHz including the Frsky R9M and TBS Crossfire typically use a single dipole antenna on the receiver. The optimal antenna positioning can be different from traditional 2.4GHz systems with diversity monopole antennas on the receivers.
You might wonder, “isn’t Crossfire faster than SBUS? Why would you still want to use it?” Well yes, you should use CRSFÂ over SBUS whenever possible. Crossfire requires both RX and TX pins of a UART while SBUS only needs the RX pin. When you don’t have a spare UART that then your next option would be using SBUS.