300 



BELL SYSTEM TECHNICAL JOURNAL 



iterative impedance characteristics. All of the band-pass filters can 

 be made impedance-transforming by varying the ratios of the im- 

 pedance elements for the two ends. 



VI. Experimental Results 



Several filters and transformers of the types discussed above have 

 been tested experimentally and have been found to give operating 

 characteristics in accordance with the calculated results. Figure 13 



MEASURED 

 INSERTION LOSS 



reflection gain 

 (each end) 



Vs^-^-^.-X-^- 



-'>-^^-^----<^^--^- 



80 90 100 110 120 



FREQUENCY IN MEGACYCLES 



140 



Fig. 13 — Measured insertion loss of a wide-band transformer. 



shows the measured insertion loss of a wide-band low-impedance trans- 

 former which transforms from 70 ohms down to an impedance of 17.5 

 ohms. The useful transformation band is from 80 megacycles to 120 

 megacycles. The measuring circuit is shown in Fig. 14. It consists 



;,j/j/;;,wt.w!/t//jiiin ;^ 



70cj 



-VvW- 



YZZ7ZZ2ZZZZZ, 



I Ml 111^ i-rrr% 



>>>^>l>> til > I )j . I ijjj jjt 



-V2 



^l.tim l}}i:iiiii:i inn!}iiiiiii*iiik 



r" 



Fig. 14 — Measuring circuit for a transformer. 



