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Radiation pattern analysis of reflector antennas

1985; Wiley; Volume: 68; Issue: 4 Linguagem: Inglês

10.1002/ecja.4410680411

8756-6621

Makoto Ando,

Antenna Design and Optimization

Abstract A method is proposed for accurately calculating the radiation pattern of reflector antennas in the entire angular range from the main beam direction to the off axis region. The principle of the method is similar to the physical optics diffraction theory, and consists of the result obtained by conventional physical optics corrected with the contribution from the edge current calculated by the geometrical theory of diffraction. However, the edge current is expressed in a simple form by means of a local coordinate system defined by the peripheral line and the mirror normal at each edge point and of the incident electromagnetic vector components in reference to this coordinate system. Therefore, it is possible to treat an arbitrarily shaped mirror surface and an antenna with a primary radiator using an arbitrary pattern. It is confirmed that the results obtained by the present method approach those obtained by the physical optics method near the main beam and those obtained by the geometrical theory of diffraction at the off axis. Accuracy is tested by applying the present method to the problem of diffraction from a circular disk for which a rigorous solution exists. The present method makes unnecessary the distinction of the use of physical optics (main beam) and the geometrical theory of diffraction (off axis) performed so far, in an empirical manner. It is possible systematically to obtain the pattern near the first‐third side lobes where two methods may be connected.