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THE BELL SYSTEM TECHNICAL JOURNAL 



Fig. 15 — A special experimental transducer for injecting the TEoi mode and' 

 receiving the converted TE02 mode in a 5" diameter waveguide. 



continues to the piston by path 4 (with dashed Hnes and crosses) 

 and then returns and is received by the TE02 part of the transducer. 

 This appears on the trace photo as the TE02 first conversion. When the 

 main TEoi energy reflected by the piston comes back to the mode filter, 

 conversion again takes place to TE02 • This is shown by path 3 hav- 

 ing dashed lines and circles. This returns to the TE02 part of the trans- 

 ducer and appears on the trace photo as the TE02 second conversion. 

 In addition, a small amount of energy in the TE02 mode is generated 

 by the TEoi upper part of the transducer. It is shown by path 5, having' 



OUTGOING PULSE 



TEoi 



ROUND 



TRIP 



TE02 



SECOND 



CONVERSION 



TE02 



FIRST 



CONVERSION 



TE02 



ROUND 



TRIP 



' 



MODE FILTER 



Fig. 16 — Trace photos and waveguide paths traveled when measuring TEoi, 

 to TE02 mode conversion at a mode filter with the transducer shown on Fig. 15 



All 



