The frequency to use in determining the attenuation constant, ot. can be chosen fairly well from the pulse width. For example, a rectangular pulse of width T seconds has an energy spectrum that has an upper half-power point at f = 1/(2. 2 T), goes to zero at f = 1/T, and has a maximum energy per decade of frequency at f = 1/(2. 5T). So an equivalent frequency of l/(2T) is a reasonable compromise, and this value of frequency produces good agreement with experimental values.

Table 5-1 shows calculated and experimental values of attenuation (! Vr I /I VI) for various cables. ,

It is useful to express the attenuation constant, о, in terms of independently variable quantities to facilitate its minimization:

2. 78 x 105 77 . b log 10 ‘ (b/a)