Telex 38109-977 manual Installation, Coaxial Cable Loss Chart

Table 7.1 Coaxial Cable Loss Chart

Attenuation (dB per 100 feet) at the frequency given

	220 MHz	450MHz	700MHz	900MHz
Times LMR-400	1.8	2.7	3.4	3.9
RG-8/U	2.9	4.5	5.8	6.7
RG-213/U	3.5	5.2	6.7	8.0
Times LMR-240	3.7	5.3	6.6	7.6
RG-8/X	6.0	8.6	10.7	12.8

Results are calculated and can vary.

Figure 7.16 The typical parts of coaxial cable.

Installation

Having all the right gear and all the proper frequencies selected is a good first step to having a top notch, highly effective, wireless communications system. However, having the right stuff is not enough, it has to be installed properly or it is all for not. In this section we take the time to cover the most common do’s and don’ts of installing a wireless system that actually works!

We’ll start with the general conceptual strategy for selecting a location for the RF equipment to live. Unlike hardwired communications systems, that can be tucked away almost anywhere, wireless systems must have prime real estate locations due to the extremely limited length of the coaxial cables that connect the transmitter and receiver to their respective antennas. As discussed in the previous section, the length of the antenna cables in a wireless system should rarely exceed 100 feet, and in some cases they should be kept much shorter due to frequency and cable loss. Because of this, selecting the location of transmitter and receiver equipment is absolutely critical to system performance.

First of all, it is necessary to determine all of areas where coverage is absolutely necessary. These are the ‘no compromise’ areas, and your system must be designed and installed to consistently meet or exceed these minimum operational requirements. Anything you can get after these areas is gravy. Select a location for the wireless base station that is centrally located in the “must work” area whenever possible. Obstacles like buildings, cars, trees outside, walls, cameras, lighting, and equipment racks inside all act as factors to limit range. If they are in the direct line of site between the base station antennas and the

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