72 NETWORK REALIZATION OF OPTIMUM PERFORMANCE [Ch. 7 



4. Amplifiers of the class U < can be optimized by first transforming 

 them into the class U > 1 by lossless nonreciprocal imbedding. The optimi- 

 zation methods \ to Z can then be applied to this class. 



5. Negative-resistance amplifiers (0 < Z7 < 1) can be optimized by first 

 transforming them into the canonical form. The terminal pair of the canon- 

 ical form that possesses the exchangeable power of smaller magnitude is 

 connected into a lossless circulator with a positive (1-ohm) balancing resistor, 

 as shown in Fig. 7.3. The resulting unilateral two-terminal- pair network, 

 driven from a 1-ohm source, achieves the optimum noise measure. 



