Communications: radio wave antennas – Antennas – Microstrip
Patent
1998-09-15
2000-02-29
Wong, Don
Communications: radio wave antennas
Antennas
Microstrip
343824, 343853, H01Q 138
Patent
active
060314915
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field the Invention
The present invention relates to a broadband printed array antenna intended to deliver a substantially axisymmetric main lobe about an axis passing through its centre.
2. Discussion of the Background
It is now well known that, in order to produce compact antennas, a particularly beneficial solution is the use of printed array antennas. Among the various possible types, patch antennas are still hardly used despite their benefit, due to the ease of production using known techniques for fabricating printed circuits.
In certain applications such as, for example, enclosed-space measurement radars, it is particularly important to have a broadband microwave antenna whose radiation pattern is substantially axisymmetric.
Although this can be achieved with conventional types of radiating elements, such as horns etc., the problem encountered is that of an often considerable lack of compactness.
SUMMARY OF THE INVENTION
A subject of the invention is therefore a printed array antenna which is very compact owing to the use of patches and exhibits a substantially axisymmetric pattern over a very broad band.
According to the invention, there is therefore provided a broadband printed array antenna for delivering a substantially axisymmetric main lobe about an axis passing through the centre (A) of the antenna, the said antenna comprising a plurality of substantially square radiating patches fed by microstrip lines, characterized in that the feeding by the said lines from the centre (A) of the antenna is of the tree-like type and in that each patch is fed through a corner by one of the lines which partially overlaps the said corner.
To obtain as clean as possible a radiation pattern, according to another aspect of the invention, there is moreover provision that in at least one direction of the plane of the antenna (E, H, D), the distribution of the patches is not periodic so as to limit the side lobes in the radiation pattern of the antenna and to move aside the array lobes, the patches at the periphery of the antenna in this direction exhibiting a spacing greater than that of the patches towards the centre of the antenna.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be better understood and other characteristics and advantages will emerge with the aid of the description below and of the appended drawings in which:
FIG. 1 is a plan view of the antenna according to the invention.
FIG. 2 is a partial sectional view;
FIG. 3 represents a patch and its feed line;
FIGS. 4 and 5 are diagrams illustrating the improvement in the performance by virtue of the nonperiodicity of the patches;
FIG. 6 illustrates a conventional central cross feed of the antenna;
FIG. 7 illustrates the central feed according to the invention;
FIGS. 8 and 9 show the radiation pattern in the plane H at the highest frequency, in the case of FIG. 6 and of FIG. 7 respectively;
FIGS. 10 and 11 are the patterns in the planes E and D at the highest frequency for the antenna according to the invention; and
FIGS. 12 to 14 represent the radiation patterns of the antenna according to the invention in the planes H, E and D for the lowest frequency.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a plan view of the antenna according to the invention. This antenna 1 uses an array of patches 10, 11 distributed over a surface which is here bounded by an octagon, although this is in no way limiting. These patches are fed by an array of feed lines 40 from a central point A where the signal is applied, for example by way of a coaxial.
The structure of the antenna will be better understood with the aid of FIGS. 2 and 3. FIG. 2 is a partial section through the antenna 1. The antenna is made according to the technique of printed circuits and comprises a first dielectric layer 12, made for example from polypropylene, one face of which bears a metallization 13 serving as earth plane and the other face of which comprises the patches 10 (one of them is represented). Applied to the face bearing the patches
REFERENCES:
patent: 4083050 (1978-04-01), Hall
patent: 4560445 (1985-12-01), Hoover et al.
patent: 4686535 (1987-08-01), Lalezari
patent: 5453754 (1995-09-01), Fray
patent: 5646634 (1997-07-01), Bokhari et al.
patent: 5838282 (1998-11-01), Lalezari et al.
Daniel Jean-Pierre
David Jean-Pierre
Gaudin Daniel
Himdi Mohamed
"Thomson-CSF"
Clinger James
Wong Don
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