Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
1998-09-25
2001-05-22
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S817000, C343S829000
Reexamination Certificate
active
06236367
ABSTRACT:
The present invention relates to a radiating element. Particularly, although not exclusively, the present invention relates to an aperture coupled, stacked patch-type radiating element suitable for dual polarised operation in a linear antenna array.
Usually, a dual polarised radiating patch element is realised by separately exciting two orthogonal resonant modes in a patch above a ground plane. In order to achieve similar operational characteristics for the two polarisations, and, most importantly, to achieve good isolation between the two ports, the patch and feed topology is usually chosen to have two orthogonal planes of symmetry, invariant under a rotation of 90°.
To widen the return loss bandwidth, the volume enclosing active current carrying parts and strongly coupled fields around the radiating element should be enlarged. In the case of a patch element, this can be achieved by raising the patch higher above the ground plane, and adding closely coupled parasitic patch elements. Parasitic elements adjacent to the main patch usually have profound effects on the radiation patterns, therefore a stacked patch configuration is usually preferred. Parasitic elements have been used to adjust band width rather than beam width. The effect of parasitic elements on the radiation pattern has been viewed as a problem with parasitic elements. A feed arrangement via an aperture in the ground plane provides a strongly coupled, non-contact connection between the feed network and the patch.
A dual polarised antenna element is driven from two ports, each port exciting one of the two orthogonal polarisations of the element. Three criteria must usually be met as follows:
1. The return loss at each port must satisfy a certain minimum level over a given frequency band.
2. The co- and cross-polarised radiation patterns associated with excitation of each of the two ports must satisfy certain specifications (i.e. co-polarised beam widths and side lobe levels, low cross-polarised radiation levels etc).
3. Isolation between the two ports must satisfy a certain minimum allowed level.
It is an object of the present invention to provide a patch-type radiating element allowing the beam width of the element to be easily adjusted or to at least provide the public with a useful choice.
According to a first aspect of the invention there is provided a patch-type radiating element including a non-planar patch shaped to produce a desired beam pattern when excited by the driven element.
The patch preferably has only first order symmetry and may consist of two planar portions disposed at an angle to one another. They may be disposed at an angle of between 178° and 135°, preferably between 175° and 150°.
In one preferred construction the patch-type radiating element is excited by two driven elements which excite two orthogonal resonant modes in the patch and wherein the plane of symmetry of the patch is aligned so that the beam width of one resonant mode is varied substantially more than the beam width of the other resonant mode. Preferably two or more stacked patches are employed, each successive patch being bent by an increased amount and aligned along the common plane of symmetry.
It will be appreciated that the above aspects may be employed individually or in combination as required.
According to a further aspect of the invention, there is provided a radiating element including a patch and auxiliary elements fed directly from a central region of the patch.
There is also provided a radiating element comprising: a ground plane; a first patch spaced apart from the ground plane; a second patch provided spaced apart from the ground plane and a first edge of the first patch; and a driven element provided between the first patch and the second patch being positioned to excite both the first patch and the second patch.
There is further provided a radiating element comprising: a first driven element, and a lower patch, driven by the first driven element, having notches in the edges thereof positioned to increase coupling with a first aperture.
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patent: 5200756 (1993-04-01), Feller
patent: 5241321 (1993-08-01), Tsao
patent: 5471221 (1995-11-01), Nalbandian et al.
patent: 5734350 (1998-03-01), Deming et al.
patent: 5949376 (1999-09-01), McDonald et al.
patent: 16207/97 (1997-09-01), None
patent: 2 685 130 (1993-06-01), None
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Jun. 1998, Australian Patent Office International—Type Search Report.
Du Toit Cornelis Frederik
Ehlen Mathias Martin Ernest
Hutchinson Richard John
Thomson John Heywood
Deltec Telesystems International Limited
Merchant & Gould P.C.
Phan Tho
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