The doublet antenna is dipole antenna with a resonant symmetric feeder line. It can be connected to a symmetric antenna tuner if it is connected to a common transceiver with unbalanced antenna connector. Even though for simple balancing the antenna a 4:1 balun could be used, the impedances will differ in general.
The main concept of this multiband antenna is that the radiating element doesn't have to be resonant at any particular frequency, although there are certain lengths (radiator length AB + feedline length BE) to be avoided.
US Military personnel occasionally use a 'doublet' antenna, especially during dismounted unconventional warfare. A radio operator may choose to bring several doublet antennas for different frequencies, such as an antenna cut to length for the set MEDEVAC (medical evacuation) frequency, NCS (net control station) frequency, and tactical frequency (the frequency used by troops in the field).
This approach may not be acceptable depending on the mission due to the fact that a doublet antenna will not work with the standard SINCGARS radio when using frequency hopping (FH) but is effective for single channel (SC). A doublet antenna is more practical for radios not intended for FH.