Communications: radio wave antennas – Antennas – Balanced doublet - centerfed
Reexamination Certificate
2003-01-07
2004-08-03
Nguyen, Hoang V. (Department: 2821)
Communications: radio wave antennas
Antennas
Balanced doublet - centerfed
C343S786000
Reexamination Certificate
active
06771226
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates in general to antennas and, more particularly, to three-dimensional wideband antennas.
BACKGROUND OF THE INVENTION
Broadband or wideband radiators or antennas are used in many applications, including various radar, navigation, and weather applications, for example. A particular class of wideband antenna, the tapered-element antenna, has become increasingly popular for use on aircraft for various radar applications. Tapered element antennas include flared notch or Vivaldi radiators, which typically include a pair of relatively large and relatively planar conductors, or radiating elements, operable to radiate electromagnetic signals into the atmosphere. The radiating elements are separated by a gap that is relatively narrow and substantially parallel near one end (the input end) of the radiating elements, and that gradually increases in width as the radiating elements curve away from each other toward the other end (the flared end) of the radiating elements.
To transmit electromagnetic signals from a flared notch or Vivaldi radiator, RF power is applied from a “balanced”source connected to the input end of each radiating element by a separate lead, such as by the leads of a coaxial cable used with a balun, for example. As the electromagnetic energy propagates along the narrow portion of the gap between the radiating elements, there is little or no radiation due to the cancellation of electromagnetic energy caused by counter-phasing of the parallel or near-parallel electromagnetic field within the gap. As the electromagnetic energy propagates toward the flared portions of the radiating elements, the transverse components of the electromagnetic field within the gap become additive (in other words, in phase) and as a result, an electromagnetic field is radiated outwardly from the wide portion of the gap.
Generally, the radiation field pattern generated from and/or received by a traditional, planar flared notch or Vivaldi radiator is linearly polarized. For example, if a flared notch radiator is positioned to lie in the horizontal plane, the radiation field pattern associated with the radiator is said to be horizontally polarized. In addition, the radiation field pattern generated from and/or received by a traditional two-dimensional, planar flared notch or Vivaldi radiator may be relatively well defined relative to certain “principal planes.” One such principal plane is the plane in which the radiator lies, commonly referred to as the “E-plane.” The radiation field pattern may, to some limited extent, be controlled in the principal planes by selecting or adjusting the planar dimensions of the radiating elements comprising the radiator.
SUMMARY OF THE INVENTION
The present invention provides a three-dimensional wideband antenna having one or more three-dimensional antenna elements. The radiation field pattern generated by the antenna may be substantially controlled in both principal planes, the E-plane and the H-plane, based on the three-dimensional shape of the antenna elements.
According to one embodiment, an antenna operable to radiate electromagnetic waves in a three-dimensional radiation field pattern is provided. The antenna includes one or more radiators, each including one or more radiating elements having a three-dimensional shape. The three-dimensional shape of each radiating element varies in each of the three standard orthogonal coordinate dimensions.
According to another embodiment, a method of producing a three-dimensional radiation field pattern is provided. The method includes radiating electromagnetic waves from an antenna comprising one or more radiators, each including one or more radiating elements having a three-dimensional shape. The three-dimensional shape of each radiating element varies in each of the three standard orthogonal coordinate dimensions.
According to yet another embodiment, a method of designing an antenna is provided. The method includes generating, using computer aided design software, a model antenna comprising one or more radiators. Each radiator comprises one or more radiating elements, each having a three-dimensional shape. The method further includes determining, using computer aided design software, the three-dimensional radiation field pattern associated with the model antenna. The shape of the three-dimensional radiation field pattern is defined at least in part by the three-dimensional shape of each of the radiating elements. The method further includes determining whether the three-dimensional radiation field pattern associated with the model antenna is satisfactory. The method further includes adjusting the three-dimensional shape of at least one of the one or more radiating elements if the three-dimensional radiation field pattern associated with the model antenna is not satisfactory.
Various embodiments of the present invention may benefit from numerous advantages. It should be noted that one or more embodiments may benefit from some, none, or all of the advantages discussed below.
One advantage of the invention is that a three-dimensional antenna may be provided that has a radiation field pattern that may be substantially controlled in all three dimensions based on the shape, dimensions and configuration of the antenna or the antenna's components (such as radiating elements, for example) in all three dimensions. This may result in a stronger or more focussed electromagnetic field as compared to electromagnetic fields produced by traditional two-dimensional antennas, particularly in the direction or plane (commonly referred to as the “H-plane”) orthogonal to the plane in which the antenna (or each radiator of the antenna) generally lies (commonly referred to as the “E-plane”). Thus, less power may be required using such a three-dimensional antenna to produce a radiation field pattern having particular field strengths over particular spatial volumes than would be required using a traditional two-dimensional antenna. As a result, input energy to the antenna may be spatially concentrated, which may be particularly beneficial in limited power applications, such as onboard a manned or unmanned aircraft, for example.
Another advantage of the invention is that the antenna or the antenna's components (such as radiating elements, for example) may be modeled using computer aided design (CAD) software and simulated using electromagnetic software to determine the radiation field pattern associated with such antennas or antenna components. Thus, a radiation field pattern having a desired pattern or one or more particular parameters may be achieved by selecting and adjusting the shape, dimensions and configuration of an antenna or antenna component using such CAD software. In addition, the antenna and/or antenna components may be manufactured or constructed using fully or at least partially automated systems or methods. For example, CAD software may be used to generate instructions for manufacturing antennas or antenna components according to models generated as described above, and such instructions may be used by automated or at least partially automated manufacturing devices to physically manufacture or construct the antennas or antenna components.
Other advantages will be readily apparent to one having ordinary skill in the art from the following figures, descriptions, and claims.
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Fulbright & Jaworski LLP
Nguyen Hoang V.
Northrop Grumman Corporation
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