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RF, Antenna and Satellite DistributionWritten by Administrator
4/1/2010RF distribution refers to the availability of antenna, CATV, satellite and local modulated video content in various rooms and areas throughout the house. RF distribution takes place on coaxial cable. RG-6U is best, though RG-59U is acceptable. The primary difference between the two is the high frequency attenuation, as related to the length of the run, and the quality of the shielding. A good quad-shield RG-6U is the very best choice for RF distribution.
There are two ways to handle a simple MATV or CATV distribution system - tapped or home run. Tapped systems have a single trunk line with 75-ohm drops used for each antenna feed location. Taps have a feed-through port and a drop that costs about 3.5 decibels of signal strength (in this case the signal is voltage dependent and not power dependent - in voltage dependent systems the total voltage is halved when the signal drops 6dB). Taps are easy to install and will service most simple antenna needs.
Home run systems require that a coaxial cable be run from each antenna location to the equipment closet. This can be a more flexible system in that IR controls, satellite IF and other signals can be "piggy backed" on the RF signal. Also, specific sources can be modulated and delivered to only certain locations. The disadvantages of a home run are the additional wiring and labor costs - as well as the need for distribution amplification. The use of RF amplification is a subject fit for an article in and of itself and is a topic we will explore in a future column.
DBS distribution is a bit trickier as it requires sweep-tested components capable of passing a full 3GHz bandwidth - with bidirectional capability. If you plan on installing a DBS satellite dish make sure you run a MINIMUM of two coaxial cables to the dish location from the equipment closet. In this way you can utilize a dual-feed LNB system with a phased array reflector for reception of signals from multiple satellite orbital locations. This is critical to getting the full measure of local-into-local or HDTV broadcast programming. Please feel free to contact us if you need more info!
