PURPOSE: To enable the unenvenness of emission to be eliminated, by bundling a lot of fine wires made of heat-proof metals such as tungsten, or the like in order to make a cathode base-body, then by impregnating the gaps of these fine wires with emitter, in the cathode of a travelling-wave tube, klystron, or the like.

CONSTITUTION: In a process A, fine tungsten wires with the diameter of about 20μm are cut down to the pieces with the length of about 30mm, which is made into a bundle of fine tungsten wires with the diameter of 5mm. In a process B, both ends of thiw wire-bundle are bound with metal wire and fixed. Next, in a process C, this wire-bundle is dipped into methyl methacrylate monomer, deformed under a reduced pressure, and vacant holes thereof are impregnated, then said methyl methacrylate monomer is polymerized to be cured. After that, in a process D, said cured substance is cut by a lathe into desired cathode shape, thus plural number of cathode base-bodies can be produced. In a process H, the emitter is impregnated to make a cathode in hydrogen atmosphere. The gaps are structurally arranged in a straight line, moreover, have no closing holes, so that at the time of emitter-impregnation, the impregnation of the cathode can be carried out very smoothly.