Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-03-24
2001-06-12
Ho, Tan (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S853000
Reexamination Certificate
active
06246370
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns a microwave antenna having individual antenna elements linked together by lines of a defined length and arranged above a ground plane. The present invention further concerns a planar microwave antenna of the generic type, having a displaceable adjustment plane adjacent to the plane in which the individual antenna elements are arranged, in which the adjustment plane has structure that has a phase shifting effect on the individual signals carried over the lines. The generic antennas may be both sending and receiving antennas.
The Blaupunkt planar antenna A60-F is an example of planar microwave antennas of the generic type. Such planar microwave antennas may be used for.
Planar microwave antennas of the generic type are known in the related art, e.g., the Blaupunkt planar antenna A60-F. Such planar microwave antennas are intended primarily for replacing satellite dishes, which have become very popular in recent years, but their external appearance may cause criticism because it interferes aesthetically with the external appearance of buildings and landscapes. Such planar antennas must be aligned with the respective satellite whose signal is to be received with two degrees of freedom (which is also the case with the parabolic antennas mentioned above) in order to yield an antenna signal with an acceptable signal-to-noise ratio. The two degrees of freedom are usually referred to as elevation and azimuth, where elevation corresponds to an angle &thgr; that is formed between the main beam direction and the main plane of the antenna, and the azimuth &phgr; characterizes the rotation of the entire arrangement about a vertical axis. Other angle designations may be selected depending upon the position of the coordinate system described.
It is believed that the planar antennas available in the past could receive signals only in the direction of incidence perpendicular to their base area. Therefore, these antennas must also be aligned mechanically.
European Patent No. 456,579 A1 concerns a planar microwave antenna where the main beam direction can be adjusted without swiveling the main plane.
With such a system, there is an adjustment pane having a means or an arrangement, which is designed in the form of a wedge, is provided to act with a defined phase shift on the respective lines originating from the individual antenna elements. This makes it possible for angle &thgr;, which is formed between the main beam direction and the base plane of the planar antenna, to deviate from 90°.
When there is only one adjustment plane displaceable in one direction, such an antenna permits swiveling of the main beam direction in only one plane, the angle between the main beam direction and the base area of the antenna, which amounts to 90° with traditional planar antennas, optionally being modified to an acute or obtuse angle, but with the main beam direction always lying in the plane formed by the vertical axis and the direction of the ascending and descending phase offset of the individual signals.
In European Patent No. 0 456 579 A1, in order to permit any desired alignment of the main beam direction of the antenna in the hemispherical space spanned by the base area of the antenna, there are two adjustment planes arranged mutually perpendicular, thus permitting phase shifts of individual signals in two mutually perpendicular directions.
Such an antenna theoretically achieves the object of creating a planar antenna that can be mounted unobtrusively parallel to a wall or another flat surface, e.g., on residential buildings and the like, where the adjustable directional characteristic of the antenna ensures reception in any desired position or spatial orientation of the base area of the antenna.
However, the planar antenna having an adjustable directional characteristic, as in European Patent No. 0456 579 A1, has a few disadvantages which greatly limit its practical applicability. First, means which are to have a phase shifting effect on the individual lines run perpendicular to these lines, but the wedge-shaped design of the elements having a phase shifting effect, as in European Patent No. 0456579 A1, require a certain thickness of the adjustment plane and thus may pose problems from the standpoint of manufacturing technology.
In addition, the design having two adjustment planes arranged mutually perpendicular may be complicated and makes the antenna expensive.
SUMMARY OF THE INVENTION
Therefore, an object of an exemplary embodiment of the present invention is to improve upon an antenna of the specified generic type, so the phase shifting elements can be manufactured on the adjustment plane in a simpler manner and less susceptible to mechanical problems.
It is believed that this object may be achieved with a generic planar microwave antenna having lines that are in which each interrupted, each point of interruption is assigned an essentially U-shaped conductor section arranged on the displaceable plane. The active length of this U-shaped conductor section being variable by displacing the adjustment plane.
Due to the interruption provided in the lines, the essentially U-shaped conductor section assigned to each point of interruption functions at the same time like a variable draw-out line, so the transit time of the signal and thus its phase angle can be influenced. The phase shift/transit time elements provided on the adjustment plane according to an exemplary embodiment of the present invention may be arranged on the adjustment plane by various manufacturing techniques or conductor techniques, including microstrip lines, triplate lines or strip lines, suspended substrate lines, slot lines, coplanar lines, coplanar strip lines.
The adjustment plane is particularly preferably arranged between the ground plane and the plane of the individual antenna elements. The U-shaped conductor sections may be linked galvanically or by a mixture of inductive and capacitive coupling.
The angle between the main beam direction and the main plane of the antenna can be adjusted by displacing the adjustment plane, but preferably the adjustment plane is designed in the form of a foil having tension elements acting on its edges. Such tension elements may include, for example, screws arranged on opposite sides, permitting movement of the adjustment plane in the form of the foil in each case in one direction.
According to an exemplary embodiment of the present invention, precisely one adjustment plane may be provided to simplify the mechanical design of the antenna. To nevertheless allow the main beam direction to be directed in space at a given angle &thgr; between the main beam direction and the antenna plane, a refinement of the planar microwave antenna according to an exemplary embodiment the present invention provides in that the antenna plane is mounted so it can rotate, so that an angle &phgr; about the vertical axis is also adjustable.
In comparison with European Patent No. 0 456 579 A1, for example which defines the generic type, a simplified design is achieved in this way which can also be manufactured less expensively because of the specific design of the elements having a phase shifting effect while also being less susceptible to defects.
Another disadvantage of the planar antenna art of this generic type according to European Patent No. 0 456 579 A1 is that the planar element may be suitable only for left circular polarization (LHCP) and right circular polarization (RHCP).
Therefore, another object of an exemplary embodiment the present invention is to create a planar microwave antenna that is suitable for any types of polarization.
This object is achieved with a microwave antenna having individual antenna elements linked together by lines of a defined length and arranged above a ground plane, characterized by a two-shell design, each shell having at least one plane containing individual antenna elements, and in which the direction of the individual antenna elements of the first shell runs perpendicular to the preferred direction of the individual antenna eleme
Ho Tan
Kenyon & Kenyon
Robert & Bosch GmbH
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