| 摘要 |
PURPOSE:To moderate the lowering of a gain in proportion to the increase of an angle theta, by increasing the gain when the angle theta is 0 deg. by forming an antenna with two stages, and shortening a space between aperture planes at respective stage shorter than one wavelength of a free-space wavelength. CONSTITUTION:Conductor plates 11 and 21 form pairs respectively, and the insides of them are connected to an outside conductor 2 sandwiching the slit group of a flat surface S11, and those plates are formed in umbrella shapes facing a flat surface S0. Conductor plates 12 and 22 similarly form the pairs sandwiching the slit group of a flat surface S12. It is assumed that a space between a flat surface S21 that intersects orthogonally with a center axis CL, and bisects the aperture plane formed by the conductor plates 11 and 21, and a flat surface S22 having the same relation with the conductor plates 12 and 22, is set as l2. The space l2 is set shorter than one wavelength of the free-space wavelength. By the above setting, the angle theta by which the gain goes to null, is larger than 30 deg., and the lowering of the gain in proportion to the increase of the angle theta can be moderated than that in a conventional two-stage nondirectional antenna.
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