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Abstract

The base station antenna for a subscriber radio system is required to have a beam with sector section in the horizontal plane and cosecant-square beam in the vertical plane. This paper proposes a method for shaping the reflector surface of the antenna so that it forms the required beam in the two planes and also presents the experimental results for a test antenna. It is shown that adequate characteristics can be obtained by this shaping method even for a single reflector. In this method the central cross-section curve obtained as a solution of a two-dimensional problem is used as the initial condition and then the reflector coordinates are successively determined from the conditions of the elevation angle of the ray reflected at the surface. The test antenna is a 90° sector beam antenna with aperture of about 52δ in the vertical plane and about 43δ in the horizontal plane. The experimental results indicate a gain of 23.5 dB at the peak and more than 20 dB within an angle of 1.5° in the vertical plane. The antenna beam realizes a sectoral section in the horizontal plane and a cosecant-square section in the vertical plane to a level as low as -10 dBi. The results demonstrate the effectiveness of the present reflector shaping method.