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200 W. C. MILLER AND H. R. KIMBALL yol 43, No. 3
value as the line resistance. Resistors RAl, RA,, RBl, and RB.2 form the variable portion of the constant B attenuator. They correspond to the tapped resistors used in conventional attenuators. Constant B attenuators may be constructed physically in the same manner as conventional attenuators except that provision must be made to vary 4 resistors instead of the usual 2 or 3 resistors. The reactors JXi and JX2 are general in their circuit arrangement but, as before, must be inverse to each other; (JXi) (JX2) = Ro2. In association with the constant B attenuator they complete a constant B equalizer.
The numerical impedance of any theoretically pure reactance or combination of reactances, as JXi and JX2 are assumed to be, varies, with frequency between a zero value at the resonant frequencies and an infinite value at the anti-resonant frequencies. For 2 mutually inverse reactances, one passes through zero reactance at the frequency for which the other exhibits infinite reactance, and conversely. Referring to Fig. 11 at the frequency for which JXi is zero and JX2 is infinite, the resistances RAl and RAz are in parallel and RBl and RBZ are in series. Also, at the frequency for which JXi is infinite and JX2 is zero neither of the resistances RAl nor RBl is effective in the circuit. This, then, fixes the minimum and maximum losses over the frequency range. Using Eq (1) and letting RP be the parallel resistance of RAl and RAz we have
Maximum Loss = 20 Logio fl + TT^ I Decibels (2}
L ±M> J
Minimum Loss = 20 Logio fl + ~~\ Decibels (3)
Another loss called the equalization loss or simply equalization, is defined as the difference between the maximum and minimum losses, that is
Equalization = Maximum Loss — Minimum Loss
Equalization = 20 Logio
"11*1 J + tf.
Decibels (4}
Note that equalization, as herein used, is a difference value not depending on frequency. For any particular design the equalization is varied by means of a control dial associated with the constant B attenuator. In most cases it is convenient to arrange the equaliza