FIELD EMISSION CATHODE AND ELECTROMAGNETIC WAVE GENERATING DEVICE USING THE SAME

PROBLEM TO BE SOLVED: To provide a simple and miniaturized field emission cathode, capable of generating an electron beam modulated by an optional frequency in a millimeter wave or a microwave band with high output and high efficiency, and an electromagnetic wave generating device using it. SOLUTION: A needle-shaped cathode chip 11a is formed on the surface of a collector 11 of a n-type semiconductor material, a gate 13 having an opening 13a formed so as to surround it is provided, a base 14 of a p-type semiconductor material is formed on the other surface of the collector, and an emitter 15 of a n+-type semiconductor material is formed on the surface of the base. An electron beam modulated by a high frequency is emitted from the cathode chip 11a with a high output and high efficiency, by connecting a high frequency power supply 18 between a base electrode 16 and an emitter electrode 17 and connecting a dc power supply 19 between the collector 11 and the gate electrode 13. Electromagnetic wave in the millimeter wave or the microwave band can be generated with high output and high efficiency, by making this electron beam interact mutually with a high frequency circuit.