400 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1957 



56 



48 



_] 



UJ 



5 40 

 u 



UJ 



Q 



z 32 



o 



-" 24 

 q: 



LU 

 ll_ 

 10 



z 16 

 < 



tr 



3.4 3.8 4.2 4.6 5.6 6.4 7.2 8. C 8.8 9.6 10.4 11.2 



FREQUENCY IN Kl LOMEGACYCLES PER SECOND 



12.0 



12.8 



Fig. 9 — Transfer loss of 4-kmc coupler in 4-, 6- and 11-kmc bands. 



in 



_i 



- b 

 U 



LU 

 Q 



? ^ 



in 

 <n 



3 3 

 a: 



-2 



< 



sr 



I- 



3500 3700 3900 4100 4300 



FREQUENCY IN MEGACYCLES PER SECOND 



4500 



Fig. 10 — Transfer loss of 4-kmc coupler in 4-kmc band. 



4-KMC DESIGN 



The use of periodic loading in the rectangular guide is not suitable for 

 use in a 4-kmc coupler design. When the phase constants are made equal 

 in the 4-kmc band, the resulting difference of phase constants in the 

 G-kmc band is too small to create a sufficiently high transfer loss in that 

 band. Periodic loading can produce the desired result. 



