DESIGN OF REACTIVE EQUALIZERS 



721 



which Hmits ihe response over any specified frequency band. For purj)oses 

 of analysis and design, it is convenient to represent the coupling transformers 

 in the manner indicated. By adopting this equivalent representation of a 

 physical transformer, the so-called high-side equivalent circuit of the trans- 

 former, which includes the leakage reactance, the magnetizing inductance, 

 and the input and output winding capacitances, is incorporated as part of 

 the coupling network itself. 



By excluding the ideal transformer portion of the equivalent represen- 

 tation of the physical transformer from the network itself, a simpliftcation 

 is possible. As shown in Figs. 6 and 7, the combination of the resistance Rl 



IDEAL 



Fig. 4 — Output coupling circuit. 



Fig. 5 — Input coupling circuit. 



and the ideal transformer may, in each case, be replaced by a resistance 

 Ro = o^Rl , where "a" is the step-up turns ratio of the ideal transformer. 

 Rl is the specified resistance, and Rq and "a" are determined in the design 

 procedure from the maximum response obtainable with the prescribed 

 capacitance Cn in the termination. 



The starting point for the study of these circuits is a consideration of the 

 limitation on the amplitude response of these networks with frequency due 



to the presence of C„ in the terminations. Since the current ratio — in Fig. 6 



and the voltage ratio ~ in Fig. 7 might be as large as desired if it were not 



for the presence of C„, the immediate problem is that of relating the magni- 

 tude of these ratios, as functions of the real frequency, to the capacitance C„. 

 This relationship is dependent on a necessary condition for the physical 



