With the speedy increase of mobile data services, LTE networks develop rapidly.  All operators are facing the challenges of multi-band and multi-RAT network as GSM, UMTS, and LTE networks will co-exist for a long period.

    To adapt multi-band and multi-RAT networks, legacy antenna systems must be reconstructed. During the reconstruction process, the antennas, combiners, tower-mounted amplifier (TMA), and remote electrical tilt (RET) antennas will be combined, forming a complex antenna system.