56 BELL SYSTEM TECHNICAL JOURNAL 



the position of the TR cavity along the slotted section of the line until the 

 window is located the correct distance from the transmitting tube. This 

 now corresponds to an even number of quarter wavelengths between the 

 equivalent short-circuit plane and the junction, so that the maximum current 

 is caused to enter the cavity. The output to the receiver is obtained from a 

 small coupling loop in the TR cavity. 



Fig. 7 — Exploded view of the cavity of Fig. 6 



A similar coaxial line series branching circuit using the IB 23 is shown in 

 Fig. 8. The method of inserting the tube in the cavity is shown in Fig. 

 9 while Fig. 10 is an exploded view showing the details. 



This method of coupling a resonant cavity to a transmission line by a 

 window is not limited to the coaxial line case. A wave guide system is shown 

 in Fig. 11. The distance between the TR cavity and the transmitting tube 

 is again adjusted by sliding the cavity and its window along over a section 

 of the rectangular wave guide containing a slot. 



The ATR. In all of the systems so far described use is made of the 

 impedance mismatch conditions at the magnetron or other transmitting 

 tube terminals to prevent serious loss during the receiving period. If the 



