Abstract: A cable antenna an end part of which is connected to an oscillator that supplies a high-frequency current is disclosed. The cable antenna includes: an inner conductor; an insulating layer covering the inner conductor; and an outer conductor covering the insulating layer, wherein only one exposed part is formed in a middle part of the cable antenna in a longitudinal direction, the exposed part formed by removing at least the outer conductor, a distance L between a tip end of the cable antenna and an end of the exposed part on a side closer to the tip end is an odd multiple of a quarter of a wavelength ?, of the high-frequency current, the multiplier being three or greater, and a length G of the exposed part in the longitudinal direction satisfies the following formula (1): ?/20?G<?/4??(1) ?: wavelength (mm) of the high-frequency current.

Abstract: A cable antenna an end part of which is connected to an oscillator that supplies a high-frequency current is disclosed. The cable antenna includes: an inner conductor; an insulating layer covering the inner conductor; and an outer conductor covering the insulating layer, wherein only one exposed part is formed in a middle part of the cable antenna in a longitudinal direction, the exposed part formed by removing at least the outer conductor, a distance L between a tip end of the cable antenna and an end of the exposed part on a side closer to the tip end is an odd multiple of a quarter of a wavelength ? of the high-frequency current, the multiplier being three or greater, and a length G of the exposed part in the longitudinal direction satisfies the following formula (1): ? / 20 ? ? ? G ? < ? ? / 4 ... ?: wavelength (mm) of the high-frequency current.