RG6A/U And RG114A/U Coaxial Cables
For comparison, these cables show the following attenuation characteristics*:
RG6A/U: Down approximately 3 dB for 100 feet at a frequency of 100 Mc/sec.
RG114A/U: Down approximately 3 dB for 100 feet at a frequency of 100 Mc/sec.
5.2.4 The Effect of Temperature on PulseHeight Attenuation and DC Resistance
A variety of cables were tested for pulseheight attenuation at several temperatures. A description of the cables is given in Table 52, and the results of the tests are shown in Figure 55.
The main contributor to variation of attenuation with temperature is variation of the resistivity, д of the conductor. A plot of measured resistance of several materials, normalized to 20 mils diameter by 100 feet long, versus temperature is given in Figure 56.
Note that the theoretical data do not include calculations for the cables using nickel or nickel clad copper as conductors, because the attenuation equations are not valid for cables having conductors with magnetic properties.
Note, also, that the above procedure is valid only for cables in which the attenuation at f = 1/(2T) is not much greater than that at low frequencies. If these two attenuations are significantly different, the shape of the pulse changes in traveling along the cable and the method of calculating output pulse height would be more involved than the approximate method outlined above. The ratio of highfrequency to lowfrequency attenuations is given by
where p is in ohmmeters and a, b, and x are in feet.
♦Catalog W2, American Phenolic Corporation.
TABLE 52
CABLE DESCRIPTION
Cable 
Insulation 
Center Conductor o. d. 
Guard o. d. 
. Shield o. d. 
Length (ft) 
Capacitance • (Pf/ft) 
Characteristic Impedance 
Copper 
Quartz Fiber 
7 — 5mil strands 
75 mils 
110 mils 
103 
36.5 
56 fl 
Nickel Clad Copper 
Quartz Fiber. 
20 mils 
95 mils 
135 mils 
100 
26. 7 
. 82 a 
Stainless Steel 
Alumina. 
17 mils 
62 mils 
125 mils 
30 
124 
36 n 
Molybdenum 
Quartz Fiber 
20 mils 
95 mils 
135 mils 
102 
32.2 
56 П 
Nickel 
Quartz Fiber 
10 mils 
95 mils 
135 mils 
32. 25 
22.6 

Stainless Steel 
Quartz Fiber 
20 mils 
95 mils 
135 mils 
100 
27 
75 Л 
СЛ. ————————— .
1 ‘
~ NOTE: Quartz fiber insulated cables have braided guards and shields of 4mil wire.

Figure 56. DC Resistance Variation With Temperature — Normalized to 20 Mils Diameter