900 MHz trunked radio systems ferrite hybrid combining for closed space transmitters

The use of hybrid transmitter combining for the 900-MHz trunked radio-frequency band is discussed. Hybrid combiner design and construction are discussed. It is pointed out that the 900-MHz trunked frequency range can easily be added to existing 800-MHz and 900-MHz systems by the use of specialized transmitter and receiver combining systems. Ferrite hybrid transmitter combiners are required for the new 900-MHz trunked spectrum because the frequencies are too close for low-loss and high-Q types of cavities. Existing 900-MHz link and paging transmitters can be combined with the new trunked radios, although the higher insertion losses in the ferrite hybrid transmitter combiners require economical and technical tradeoffs