Development of a Planar Equiangular Spiral Amplifier

Abstract : Work accomplished on the development of a radial-beam traveling wave tube is described. The rf circuit used consists of a pair of planar equiangular (logarithmic) bifilar spirals deposited on ceramic substrates and placed on either side of a thin flat electron beam which expands radially from a ring- shaped cathode. A detailed analysis of the circuit properties and the wave-beam interaction is presented. A rough design procedure is also given based on certain reasonable assumptions. A computer program has been developed to aid in optimizing designs. Experimental data from three tubes are presented, in the frequency range 0.5 to 1.0 GHz.