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BELL SYSTEM TECHNICAL JOURNAL 



properties^ Thus Field^ describes an apertured disk structure (Fig. 4.8) 

 which has band-pass properties very similar to the symmetrical mode of the 

 circuit of Fig. 4.3. In this case there is no mode similar to the other mode, 

 with equal and opposite fields in the two halves. Field also shows a disk-on- 

 rod structure (Fig. 4.9) and describes a tube using it. This structure has low- 



Fig. 4.8 — This loaded waveguide circuit has band-pass properties similar to those of 

 Fig. 4.7. 



Fig. 4.9 — This disk-on-rod circuit has properties similar to those of Fig. 4.6. 



R 



(a) (b) 



Fig. 4.10— A circuit consisting of a ridged waveguide with transverse slots or resonators 

 in the ridge. 



pass properties very similar to those of the circuit of Fig. 4.5, which are 

 illustrated in Fig. 4.6. 



Figure 4.10 shows a somewhat more complicated circuit. Here we have a 

 rectangular waveguide, shown end on in a of Fig. 4.10, loaded by a longi- 

 tudinal ridged portion R. In b of Fig. 4.10 we have a longitudinal cross sec- 



•■> I'". B. Llewellyn, U. S. Patents 2,367,295 and 2,395,560. 



■* Lester M. Field, "Some Slow-Wave Structures for Traveling- Wave Tubes," Froc. 

 I.R.E., Vol. 37, pp. 34-40, Jan. 1949. 



