Microwave introduction device

A microwave introduction device comprising:

• a microwave generator for generating a microwave of a predetermined frequency;
• a mode converter for converting the microwave into a predetermined oscillation mode;
• a planar antenna member arranged toward a predetermined space;
• and
• a coaxial waveguide connecting the mode converter with the planar antenna member to propagate the microwave,
• wherein a central conductor of the coaxial waveguide is formed in a cylindrical shape,
• a base end of the central conductor is provided via a cone-shaped connection member formed on a partition wall of the mode converter,
• an inner diameter D1 of the central conductor is not smaller than a first predetermined value,
• an outer conductor of the coaxial waveguide is also formed in a cylindrical shape,
• a ratio r1/r2 of a radius r1 of an inner diameter of the outer conductor to a radius r2 of an outer diameter of the central conductor is maintained at a second predetermined value, and
• the inner diameter D2 of the outer conductor is not greater than a third predetermined value.