Communications: radio wave antennas – Antennas – Wave guide type
Reexamination Certificate
1994-06-02
2001-03-27
Blum, Theodore M. (Department: 3662)
Communications: radio wave antennas
Antennas
Wave guide type
C343S767000, C343S768000
Reexamination Certificate
active
06208308
ABSTRACT:
TECHNICAL FIELD
The invention relates to polyrod antennas, and more particularly to a new technique for feeding polyrod antennas with flared notch antennas.
BACKGROUND OF THE INVENTION
Both polyrod and flared notch antennas are part of a larger family of antennas that exploit length in the endfire direction to achieve gain. A polyrod is a cylindrical shaped polystyrene rod a few wavelengths long. Other materials such as fiberglass may be used instead of polystyrene if desired. When properly excited, the polyrod acts as an endfire aerial. Traditionally, polyrods are fed with waveguide. A matching section is usually included to transition efficiently from the waveguide to the polyrod. As with other endfire antennas, like the flared notch, the gain of the polyrod may be increased by a corresponding increase in its length in the endfire direction, as described in
The Antenna Engineering Handbook
, H. Jasik, McGraw Hill, 1961, Chapter 16, pp. 16-1 to 16-24.
The waveguide required to feed the polyrod has proven incompatible with some of the proposed applications for the polyrod. One application, adding a polyrod array to the face of a mechanically scanned slot array, would be severely constrained if not impossible to accommodate using the waveguide. Not only would the waveguide feeding the polyrods be a problem because of the aperture blockage but also the feeding network for the waveguides would require more space.
Moreover, the waveguide is bulky and requires matching sections. Secondary to this is that the system, i.e., the polyrod and waveguide, is inherently narrow banded, i.e., limited at the low end by the cut-off frequency of the waveguide.
It would therefore be advantageous to provide a technique for feeding a polyrod antenna which has reduced volume and higher gain and broader operating bandwidth than the conventional waveguide-fed antenna.
SUMMARY OF THE INVENTION
A polyrod antenna system comprises a polyrod antenna element and a feed system for feeding the polyrod element from an end thereof. In accordance with the invention, the feed system includes a flared notch antenna having a flared notch radiator section. The polyrod element is attached to the flare region of the flared notch so that the polyrod element is fed by signals as they travel along the flared notch. The antenna system operates in a first mode at which the combination of the polyrod element and the flared notch antenna act as a dielectric loaded flared notch, and in a second mode at a frequency band at which the polyrod element operates as a surface-wave antenna.
REFERENCES:
patent: 3128467 (1964-04-01), Lanctot
patent: 3518691 (1970-06-01), Hallendorff
patent: 4001834 (1977-01-01), Smith
patent: 5175560 (1992-12-01), Lucas et al.
patent: 3215323 (1983-07-01), None
patent: 0009349 (1977-01-01), None
Alkov Leonard A.
Blum Theodore M.
Lenzen, Jr. Glenn H.
Raytheon Company
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