HIGH Q RESONANT CAVITIES 



427 



knob into linear motion of the piston through a crank and connecting rod 

 assembly. Coupled to the drive shaft is an indicating dial to register 

 frequency. 



Silverplating is indicated on all interior surfaces of the cavity for minimum 

 resistance to currents in the walls and ends of the cylinder. 



For the 3 kmc bands, the input coupling is in the form of a loop protruding 

 into the cavity and connected by coaxial microwave cable to the radar under 



-PEAK POWER 

 IN ECHO BOX 



< Orr } TRANSMITTER 



k 



-RINGING TIME 



■J 



Fig. 10 — Radar test with echo box. 



test. For the 9 kmc bands, the input coupling is an orifice with which is 

 associated a wave guide to coaxial cable transducer. 



The output couplings for the two frequency bands also diflfer in construc- 

 tion. For the 3 kmc bands, the variable coupling is achieved by rotating 

 the output loop before an aperture in the cavity. In this rotary mount is 

 housed the rectifying crystal and by-pass condenser. An orifice is used for 

 the 9 kmc band output coupling which feeds a crystal mounted in a wave 

 guide. Amplitude control is by a vane attenuator in the wave guide. In 



