686 BELL S YSTEM TECHNICA L JO URN A L 



As a further confirmation of the theory, the experimental results on another 

 and longer waveguide filter consisting of fifteen resonant cavities and four- 

 teen connecting fines are given. The conclusion is reached that maximally- 

 flat waveguide filters can be designed to have excellent impedance match 

 and ofi"-band suppression qualities. 



Notation 



a Width of waveguide. 



b Height of waveguide. 



B NormaHzed susceptance. 



c Velocity of fight in free space. 



Cr Capacitance in the r* branch of a filter. 



d Width of iris opening. 



d Diameter of post in waveguide. 



d A small number <<C 1. 



€ Base of natural logarithms. 



/ Frequency, 



/o Resonant frequency. 



fc Frequency at half power point. 



few Cutoff frequency of waveguide. 



G Terminating conductance of filter. 



• ¥ 



K Susceptance parameter. 



/ Length of transmission line. 



/' Length of fine corresponding to excess phase of cavity. 



4 Length of line connecting two cavities. 

 Xo Resonant wavelength. 



Xc Wavelength at half power point. 



\g Wavelength in transmission line. 



Xa Wavelength in free space. 



Lr Inductance in r*^ branch of a filter. 



m An integer, including zero. 



n Number of branches in filter. 



Po Available power. 



Pl Power delivered to load. 



Q Loaded Q. The selectivity of a loaded circuit. 



Qr Loaded Q of the r**" branch. 



Qt Loaded Q of the total filter. 



R Terminating resistance of the filter. 



s Distance from center of waveguide. 



5 Voltage standing wave ratio. 



