MICROSTRIP ANTENNA

PURPOSE:To realize the microstrip antenna having a desired radiation directional pattern without deteriorating the absolute gain by providing a dielectric substrate which is formed so that curvatures of a first and a second rotary curved surfaces on which a radiation conductor and ground conductor are formed, respectively are different from each other, and also, the radiuses of curvature are different from each other. CONSTITUTION:Positions Q1, Q2 of the center of a circular arc of a cross section line of the lower face and the upper face of a dielectric substrate 10b formed like a rotary curved surface are different from each other, by which thickness of the dielectric substrate 10b comes to thick extending from the center of the dielectric substrate 10b to the outside peripheral edge end part direction. In the center part of the upper surface of the dielectric substrate 10b in which a ground conductor 11b is formed on the whole face of the lower face, a radiation conductor 12b being a rotary curved surface shape is formed. By exciting a linearly polarized wave microstrip antenna constituted in such a way by a microwave signal through a feeding cable 20, a microwave of a linearly polarized wave is radiated in the radiation direction D0 vertical to the radiation conductor 12b from the center O of the radiation conductor 12b.