Nec Corporation

Mitsuhiro Kusano

Kazuo Kosukegawa

Kazuhiko Kurokawa

A horn antenna for radiating or receiving a microwave is provided with a plurality of axially spaced radial fins fixedly mounted on the outer surface of the horn, which fins form a plurality of radial grooves and a front axial groove each having a depth of approximately equal to a quarter of a wavelength of the microwave. Those fins and grooves form a choke surface-wave structure which improves the radiation pattern and reduces undesired radiation and side lobe. A multimode horn arrangement for a higher frequency wave is employed for the horn so that two different frequency waves are efficiently radiated or received at a single horn antenna with a reduced side lobe and an excellent cross polarization characteristic.

Horn antenna with a choke surface-wave structure on the outer surface

A shaped beam antenna of the type comprising a main reflector and a feed horn for irradiating an electromagnetic wave upon said main reflector, the main reflector including, in sectional planes inclusive of a Y-Z plane and planes parallel thereto, a central section and horizontal side end sections adjoining the central section, where Cartesian coordinates are assumed having an origin near the feed horn, a Z-axis extending in a direction of the horizontal center axis of the feed horn, and X- and Y-axes extending in planes perpendicular to the Z-axis. The central section has a plurality of torus reflector segments and each of the side end sections has a plurality of parabolic reflector segments, and the torus and parabolic reflector segments are grouped into first and second portions, the first portion having the reflector segments which are symmetrical with respect to the Y-Z plane, the second portion having first and second sub-portions, the reflector segments of the first sub-portion and those of the second sub-portion being asymmetrical with respect to the Y-Z plane, whereby the maximum radiation direction of the beam reflected from the first portion lies in the Y-Z plane, and the maximum radiation direction of the beam reflected from the second portion lies in planes other than the Y-Z plane.

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Tokyo, Japan

Mitsuhiro Kusano