560 



ANTENNAS AND RF COMPONENTS 



Short 



Phase Shifter 



Circulator applications are many 

 and include duplexing, diplexing, 

 isolating, and switching. The circu- 

 lator is also valuable as a unity- 

 coupled directional coupler in reflec- 

 tometer applications,^^ for example. 

 Fig. 10-33 illustrates the application 

 of a four-port circulator to a novel 

 anisotropic transmission line having 

 independently adjustable propaga- 

 tion characteristics in opposite direc- 

 tions through the network. An 

 attenuator and phase shifter in series 

 with short-circuited arm 2 can 

 control the attenuation and phase 

 delay from arm 1 to arm 3, while a 

 similar arrangement on arm 4 can 

 independently control the attenuation and phase delay from arm 3 to arm 

 1. The differential attenuation and phase delay thus can be made to have 

 any desired values. 



Circulators are commercially available having forward coupling insertion 

 losses of generally less than 0.5 db. Isolation between decoupled ports 

 ranges between 20 and 40 db; in general is not the same between various 

 isolated ports, nor is the isolation necessarily the same ia opposite directions 

 between any two isolated ports. A broadband differential phase shift 

 circulator for X-band, rated at 100 kw peak pulse power, is shown in 

 Fig. 10-34. 



Fig. 10-33 Anisotropic Transmission 



Line Using a Circulator. Transmission 



Properties from 1 to 3 and from 3 to 1 



Can Be Independently Controlled. 



Fig. 10-34 Four-Port Circulator for X Band Rated at 100-kw Peak Power with 

 Less Than 0.2 db Insertion Loss. (Microwave Development Laboratories, Inc.) 



52Howard Scharfman, "Measurement of Small Complex Reflection Coefficients, 

 Convention Record, Part 8, 82-94 (1955). 



IRE 



