Communications: radio wave antennas – Antennas – Slot type
Patent
1994-11-18
1997-08-26
Hajec, Donald T.
Communications: radio wave antennas
Antennas
Slot type
343770, H01Q 1310
Patent
active
056614985
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a radial line slot antenna utilizing a radial waveguide for use in SHF and EHF bands.
BACKGROUND FIELD
Conventionally, a parabolic antenna having a bowl shape is used in a satellite communication or else; however, recently a radial line slot antenna is developed instead of the parabolic antenna.
The radial line slot antenna is disclosed, for example, in Japanese Patent Publication No. 1-13241. Namely, a pair of metal disks are opposed to each other through a spacing, one of which is formed with slots for power emission. A peripheral metal wall is fitted along edges of these metal disks to form an inner waveguide spacing enclosed by these metal disks and the peripheral wall. A feeding means is provided to feed a power to the waveguide spacing such that the fed power is converged to a central portion of the waveguide spacing from the peripheral wall. The feeding means is comprised of a feeding source connected to the waveguide spacing, and an intermediate metal plate disposed in parallel to the pair of the metal disks such as to leave a gap relative to the peripheral wall within the waveguide spacing to provide a return pass of the fed power.
Generally, with regard to a circular polarized electromagnetic radiation having a certain frequency, there exist a right-hand circular polarization which rotates rightward in a traveling direction, and a left-hand circular polarization which rotates leftward in a traveling direction. However, the conventional radial line slot antenna cannot be used commonly to both of the right-hand and left-hand circular polarizations. Therefore, there is a drawback that a separate pair of antenna must be installed for the right-hand and left-hand circular polarization waves, though these waves have the same frequency.
In view of the above noted drawback, an object of the present invention is to provide a polarization-universal radial line slot antenna which can be commonly used for either of the right-hand and left-hand circular polarizations.
DISCLOSURE OF THE INVENTION
According to the invention, the radial line slot antenna comprises a slot plate having numerous slots, a frame opposed to the slot plate, a partition plate interposed between the slot plate and the frame to form an upper layer waveguide and a lower layer waveguide, and feeding means for feeding these waveguides. Characterizingly, the feeding means comprises first feeding means composed of a coaxial line having a tip end portion which protrudes through the partition wall into the upper layer waveguide to feed the same, and second feeding means composed of a dielectric member and a conductor member, which are formed coaxially around the coaxial line to feed the lower layer waveguide.
Further, according to the present invention, the polarization-universal radial line slot antenna comprises a slot plate having numerous slots, a frame opposed to the slot plate, a partition plate interposed between the slot plate and the frame to form an upper layer waveguide and a lower layer waveguide, and feeding means for feeding these waveguides. Characterizingly, the feeding means comprises a coaxial line disposed movably through an opening formed in a central portion of the partition plate, and a conductor piece attached to a tip end portion of the coaxial line and having a diameter greater than that of the opening.
In the inventive polarization-universal radial line slot antenna, a radio wave is fed to the upper layer waveguide by means of the first feeding means, and the same radio wave is also fed to the lower layer waveguide by means of the second feeding means. In such a construction, the slots are aligned along a spiral pattern which, for example, expands clockwise from the center, hence the slots are excited sequentially from the central ones to the peripheral ones when the upper layer waveguide is fed by the first feeding means, so that a left-hand circular polarized wave is emitted from the antenna. Further, when the lower layer waveguide is fed by the second feedin
REFERENCES:
patent: 4819003 (1989-04-01), Goto et al.
patent: 5049895 (1991-09-01), Ito et al.
Ando Makoto
Goto Naohisa
Okazaki Yasuhiro
Hajec Donald T.
Phan Tho
Toppan Printing Co. Ltd.
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