A Coupled Resonator Reflex Klystron* 



By E. D. REED 



(Manuscript received March 5, 1953) 



The theory of a coupled resonator reflex klystron is developed and its 

 reduction to practice described. This tube differs from the conventional 

 reflex klystron in that its performance characteristic is derived from the 

 interaction between the electronic admittance due to a bunched electron 

 stream and the input admittance of two synchronously tuned, coupled 

 resonators. As a result: (1) power output can be made to be substantially 

 flat over the greater part of the electronic tuning range; (2) the half-power 

 electronic tuning range of the coupled resonator reflex klystron is more 

 than twice that of a klystron using the same electron optical system but inter- 

 acting with a single resonator; and (3) modulation linearity may be ob- 

 tained over a greatly increased frequency swing. 



A reduction in power output of about 3db occurs for a secondary resonator 

 Q and coupling coefficient adjustment designed to yield a maximum flat 

 band or maximum electronic tuning while a much smaller reduction in 

 output power will provide a substantial improvement in modulation linearity. 



TABLE OF CONTENTS 



1.0 Introduction 716 



2.0 Small Signal Reflex Klystron Theory 718 



2.1 Electronic Admittance 719 



2.2 Passive Circuit Admittance of Single Resonator 722 



2.3 Equivalent Circuit of Single Resonator Reflex Klystron .... 723 



2.4 Performance Analysis Based on Complex Admittance Plane 

 Representation 723 



3.0 Theory of Coupled Resonator Reflex Klystron 727 



3.1 Driving Point Properties of Two Coupled Resonators Hav- 

 ing Equal O's 729 



3.1.1 Variation of Input Impedance with Frequency 735 



3.1.2 Input Admittance Plot in g-b Plane 736 



* Submitted in partial fulfillment of the requirements for the degree of Doctor 

 of Philosophy, in the Faculty of Pure Science of Columbia University. 



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