Cable antenna, gate antenna, antenna unit, automatic conveyor shelf and unmanned cash register

A cable antenna an end part of which is connected to an oscillator that supplies a high-frequency current,

• the cable antenna is bent at a plurality of bends in such a manner that sections on both sides of a bend are not parallel to each other, so that the cable antenna forms one or more openings having the shape of a rectangle all of four sides of which have a length equal to a half of the wavelength,
• comprising:
• an inner conductor extending in a cable-like configuration;
• 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 being 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 λ of the high-frequency current, and
• a length G of the exposed part in the longitudinal direction satisfies the following formula (1)
• λ/20≤G<λ/4 (1)
• where λ denotes the wavelength (mm) of the high-frequency current.