In-Building Distributed Antenna System (DAS)

Aug. 13, 2013 - PRLog -- In-Building DAS or In-Building Distributed Antenna Systems refers to a complete system to be utilized inside buildings or facilities where cellular coverage is weak or non-existent due to building construction but where there is a usable cellular signal on the rooftop. Typically a DAS is specific to a multiple server antenna application necessary due to overall size or scope of the building(s). For the most part, there are 3 different types of DAS: a passive or coaxial based system, an active or fiber based system, or a hybrid system that is a combination of both.

Passive DAS

A passive or coaxial based DAS utilizes a donor fed BDA to redistribute signal to multiple server antennas within an infrastructure. Typically this infrastructure does not exceed 125,000 sq ft and does not have an exorbitant amount of internal concrete, mason, or metal walls that can potentially block signal. The server antennas on this type of system will typically daisy chain from the BDA through the utilization of directional couplers, taps, and/or splitters that will allow for proper balancing of signal. More than one passive DAS within an infrastructure is not recommended as that particular situation can cause interference both within the system and/or within the macro-environment. The passive DAS is typically the least costly of the three mentioned types.

Active DAS

An active or fiber based DAS utilizes donor fed BDAs to provide signal into head end equipment that will convert the RF into light for distribution over fiber to different Remote locations that will house equipment to convert the light back to RF for distribution of signal over coax to server antenna locations. Typically, for a neutral host DAS, a separate BDA is necessary for each specific carrier requested. The Remote locations are typically home run to the head end (some instances will have a slave remote that will be fed directly from the main remote). The server antennas will also be a combination of being daisy chained through the utilization of directional couplers, taps, and/or splitters and home run to the Remote.

Hybrid DAS

A hybrid DAS is a combination of both types of systems. A coaxial based, BDA fed portion of the system will daisy chain out of the MDF with the fiber based, BDA fed portion of the system home running to the different IDFs where remotes are housed.

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