Distributed Antenna System (DAS)

The concept of a Distributed Antenna System, DAS has many advantages in some applications. A Distributed antenna system, DAS is a network of antennas spaced apart from each other, but connected to a common source. In this way the DAS is able to provide wireless or radio coverage within a given area.

The idea of a distributed antenna system is being adopted increasingly as it enables a number of advantages to be gained. However this is at the cost of a larger more complicated system. Nevertheless, distributed antenna systems are being used in a variety of areas to enable the right coverage to be gained for several applications.

Although the concept of distributed antenna systems has been known about for many years, it is with the increased deployment of wireless systems within buildings and other difficult coverage areas that the idea of distributed antenna systems has come to the fore.

Advantages of using a distributed antenna system

• Better defined coverage
• Fewer coverage holes
• Same coverage using a lower overall power
• Lowers health risk as a result of using lower overall power levels
• Individual antennas do not need to be as high as a single antenna for the equivalent coverage

Disadvantages of using a distributed antenna system

• Higher cost as a result of additional infrastructure required
• Possible greater visual impact in some applications as a result of greater number of antennas, although they are likely to be much lower in height.

Basic concept of a distributed antenna system

The basic idea behind the distributed antenna system is to utilise several different antennas over the required coverage area. Using this approach the overall power required is less because these more localised antennas can be placed more effectively for a small area, rather than having a single, larger antenna that is a compromise for the wider coverage needed. By adopting a distributed antenna system approach, this helps overcome the shadowing and penetration losses because a line of sight link is available more frequently. As a result the levels of absorption are lower and this means the overall power levels can be reduced.

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