Communications: radio wave antennas – Antennas – Slot type
Reexamination Certificate
1999-08-10
2001-04-17
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Slot type
C343S770000
Reexamination Certificate
active
06219000
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to antenna elements for radar arrays, and more particularly to a flared-notch radiator having a reduced aperture return loss to cross-polarized incident plane waves.
BACKGROUND OF THE INVENTION
Single-polarization, flared-notch radiators are typically designed by optimizing the radiation performance of the element in one plane (co-polarized), without regard to its performance characteristics in the plane orthogonal to the radiator (cross-polarized). For a wave impinging upon an antenna comprised of these flared-notch radiators, this design approach results in a radiator that provides maximum absorption of the co-polarized component of the incident wave, but minimal absorption of the cross-polarized component from the radiator tips.
It would therefore be an advantage to provide a technique to improve this cross-polarization absorption component.
SUMMARY OF THE INVENTION
A flared-notch radiating element in accordance with the invention has a body portion tapering to an element tip region, the radiating element having a first thickness through a body element portion. The element tip region has reduced thickness in relation to the first thickness, the reduced thickness improving the absorption of the cross-polarized component of an incident wave.
The reduced thickness of the tip region can be provided in several ways. For example, there can be a single step reduction in the element thickness, or the tip region can have multiple stepped reductions in thickness. Another alternative is to smoothly taper the thickness from the thickness of the element body portion to an end tip thickness.
A typical application for a flared-notch radiator in accordance with the invention is in an array of flared-notch radiator elements. The array includes typically a plurality of metal sticks disposed in aligned rows, each stick defining a plurality of flared notches, with adjacent ones of the metal sticks being separated by a separation distance so as to define a respective channel between each adjacent pair of sticks. The co-polarized component of the incident wave is parallel to the channels, and the cross-polarized component is transverse to the channels. Thus, the thickness dimension being reduced in accordance with the invention is the dimension transverse to the channels between the array sticks.
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McWhirter Brian T.
Panaretos Steve K.
Alkov Leonard A.
Le Hoang-anh
Lenzen, Jr. Glenn H.
Raytheon Company
Tran Thuy Vinh
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