Single BDA vs. Multiple BDAs
Generally, an individual BDA can cover only a single public safety band. However, usually that is all that's required for most AHJs. In this example the police, fire department, and emergency medical services use UHF radios. Therefore the building only requires a UHF BDA.
An exception is that both the 700 MHz and 800 MHz bands can be covered with a single BDA. In this example, police and EMS use 800 MHz radios while the fire department uses 700 MHz radios. The building requires just one 700/800 BDA.
If required, multiple frequency bands can be covered by using multiple BDAs, one per frequency band, and combining them on a single DAS (Distributed Antenna System). Also, a UHF BDA can cover up to two UHF sub-bands. In this example, police and EMS use UHF radios and the fire department uses VHF radios. The example shows a building set up with multiple BDAs sharing the DAS. In this case, two donor antennas are needed.