ZOOM LENS CAPABLE OF SHORT-DISTANCE PHOTOGRAPHING

摘要

PURPOSE:To improve directivity and efficiency by reducing leakage radiation by providing a subordinate horn to a primary radiator. CONSTITUTION:The base part of a waveguide 4 is provided at the center part of a bipolar reflecting mirror 2. A primary radiator 6 is fitted atop of the waveguide 4. The primary radiator 6 is formed in a short cylinder or short prism shape, and a couple of slots 10 and 10 arranged with the waveguide 4 between are formed in a rear wall surface 8. On an external circumferential wall 12 succeeding to the rear wall surface 8 of the primary radiator 6, a subordinate horn 14 is fitted facing the side of the bipolar reflecting mirror 2. The subordinate horn 14 is formed in a pyramid or cone shape corresponding to the shape of the primary radiator 6 and the distance from its tip internal circumferential surface 16 to the slits 10 and 10 through a corner part 15 between the rear wall surface 8 and external wall surface 12 is lambda/4 (lambda; wavelength).