Title of Invention

"A FLAT ANTENNA FOR COMMUNICATING CIRCULARLY POLARISED SIGNALS"

Abstract A flat antenna for communicating circularly polarized signals in wireless, satellite communication systems etc. comprising a thin, flat dielectric substrate, preferably rectangular in shape having a first surface and a second surface provided with a pattern formed by conducting metallic sheet (3) on each of first and the second surface of said substrate, said pattern comprising thin and closely placed strips (4 and 5) of conducting metallic sheet (4) separated by thin strip of non-metallic strip (5), preferably of said dielectric substrate itself, and pattern being optionally coated partially with a coating selected from aluminium (7), single coating of a microwave absorber (9) double coating of microwave absorber (10) or a combination thereof.
Full Text Field of the Invention
The present invention relates to a flat antenna for communication circularly polarised signals. Even more particularly, this invention relates to a flat antenna to transmit and to receive the circularly polarised signals at microwave and millimeter wave frequencies in wireless and satellite communications.
Background of the Invention
The wirelless and satellite communication systems have expanded rapidly. The communication systems applicable in the cellular, mobile and vehicular systems have expanded recently. The recent advancements in these specialised areas have reduced the cost of the product and after sale services. This reduction of the cost has resulted in the large scale consumption of such systems. Antennas form the basis of the wireless, satellite, cellular, mobile and vehicular communication systems. The requirement of such systems is to have an antenna, which is easy to fabricate and lower in cost, light in weight, easy to transport on a system or individually. The antennas, generally working on the reciprocity principal, can work both as the transmitter antenna and as receiver antenna, and they can be analysed either in the transmitting mode or in the receiving mode.
Further, an antenna, which can radiate or transmit the circularly polarised signals, can overcome the problem of polarisation rotation, and can reduce the multipath effects. The circularly polarised signals, as referred herein, are well known in the art and
comprises of two orthogonally polarized waves, known as horizontal and the vertical components, of equal frequency and magnitude, and the energy of the wave will be the combined energy of both of these components.
The object of transmitting and / or receiving the circularly polarised signals can be acheived by the printed antennas or flat antennas. The printed antennas are generally fabricated by the printed circuit techniques. The printed antennas offer important features such as low cost, light weight and conformability to a curved surface. In addition, such antennas, which are circularly polarised, that is which can receive and/or transmit the circularly polarised signals, have applications in the systems such as mobile communication and direct broadcast from satellite, as stated above and particularly avoid the need for polarisation tracking.
The printed antennas, as known in the art, have Janus configuration or planar elements including radially disposed segments or radially arranged or sequentially arrnaged elements interconnected by an interconnect network or crank-shaped pattern comprising of U-shaped portions connected to each other or planar radiator encircled by a loop radiator or conducting radiating patch attached with tunning means to convert the polarized signals into circularly polarised signals or ground conductor plates and patches in a square arrangement or having helical coiled conductor with linear capacitance and inductance distribution or slotted pipe having helically wound conductr.
The major disadvantage of such known configurations of the printed antennas, as stated above, is that their construction is more difficult and complicated to manufacture, resulting in extra time consumption and at the same time the construction of such systems is more expensive.
Still further disadvantage of some of the known antenna systems to transmit and / or to receive the circularly polarised signals is that they usually require to split the input signal into two equal parts, one part shitted in phase with respect to the other by 90 degrees. These two parts of signal are fed to a single or a pair of radiating elements to
achieve circular polarisation, and hence making the system a complex system. Need of the Invention :-
Therefore, there is a need to have an antenna, particularly an antenna to transmit and to receive the circularly polarised signals, more particularly of an antenna to transmit and to receive the circularly polarised signals at microwave and millimeter wave frequencies in the wireless and satellite communications etc, which can overcome the disadvantages of the prior art as described and stated herein above.
Objects of the Invention :-
The present invention is therefore, directed to meet an objective to provide an antenna, particularly an antenna for transmitting and/or receiving the circularly polarised signals in the wireless, satellite communication systems etc., which is more convenient and easy to manufacture and at the same time, more economical to construct without consuming extra-ordinarily much time.
Another an object of the present invention is to make a disclosure of an antenna, particularly of an antenna to transmit and/or receive the circularly polarised signals at various frequencies, which can meet the requirements of the wireless and satellite communication systems without any change in the main configuration, and hence reducing the requirement of fabricating antennas of varying configurations and still having comparable overall performance.
Still another an object of this invention is to provide an antenna, as stated herein above, wherein the input signal is inherently suitable for circularly polarised radiation and does not require any processing of the input signal.
Further an object of the present invention is to disclose an antenna as stated herein above, which has the potential of relatively wider bandwidth and still light in weight
and comfortable to transport with any system or the individual.
This is further an object of this invention to provide an antenna, as stated herein above, which has improved operational characteristics.
This is still further an object of the present invention to provide an antenna, as stated herein above, which has reduced radiation from the connector.
Yet another an object of this invention is to provide an antenna, as stated herein above, which has capability to arrest the end radiation with improved symmetry of the radiation.
Brief Description of the Invention :-
In accordance to the objects of the present invention, as stated herein above, and other objects, the present invention provides an antenna, particularly a flat antenna for transmitting and/or receiving the circularly polarised signals in the wireless, satellite communication systems etc., comprising of a thin, flat, preferably rectangular dielectric substrate disposed with a conducting metallic sheet on both the opposite faces. A pattern, as disclosed herein below, is printed photolothographically on both the faces. The said pattern, in accordance to one of the preferred embodiments of this invention comprises of parallel, thin, closely spaced strips. The strips are alternately metallic and non-metallic in nature. The non-metallic part is preferably the dielectric substrate itself.
In accordance to the preferred embodiment of the present invention the pattern, as generated above, is partly coated with the aluminium and/or the single and/or double coating of microwave absorber, which offers the additional advantages of improved operational characteristics and reduced radiation from the connector and arresting the end radiation with improved symmetry of the radiation.
The nature of the present invention, as disclosed herein above, will be more
apparent when read in conjuction with the accompanying figures, which are not intended to limit the scope of the present invention.
According to the present invention there is provided a flat antenna for communicating circularly polarised signals in wireless, satellite communication systems etc. comprising a thin, flat dielectric substrate, preferably rectangular in shape having a first surface and a second surface provided with a pattern formed by conducting metallic sheet (3) on each of first and the second surface of said substrate, said pattern comprising thin and closely placed strips (4 and 5) of conducting metallic sheet (4) separated by thin strip of non-metallic strip (5), preferably of said dielectric substrate itself, said pattern being optionally coated partially with a coating selected from aluminium (7), single coating of a microwave absorber (9) double coating of microwave absorber (10) or a combination thereof.
Description of the accompanying drawings
Figure-1 shows the top side perspective view of the flat antenna of the present invention in accordance to one of the preferred embodiments of this invention.
Figure-2 shows the top side perspective view of the flat antenna of the present invention in accordance to another preferred embodiment of this invention.
Figure-3 shows the top side perspective view of the flat antenna of the present invention in accordance to still another preferred embodiment of this invention.
Figure-4 shows the top side perspective view of the flat antenna of the present invention in accordance to still further preferred embodiment of this invention.
Figure-5 shows the top side perspective view of the flat antenna of the present invention in accordance to yet another preferred embodiment of this invention.
Detail Description and Preferred Embodiments of the Invention :-
Accordingly, the present invention discloses a flat antenna to transmit and/or to recieve the circularly polarised signals, as stated herein above and described herein after.
Now referring to the accompanying figures, the antenna (1), as disclosed and described in the present invention preferably comprises of a thin, flat and rectangular sheet of dielectric substrate (2) coated with the conducting material (3) on both the opposite faces. The conducting material (3) forms a pattern on both the opposite faces, and said pattern consists of alternately arranged metallic (4) and non-metallic (5) strips, which are preferably thin and closely placed. The said pattern is preferably similar on both
the faces and the strips (4 and 5) are preferably parrallel to each other. The parrallel, thin and closely placed strips (4 and 5) make an angle with respect to the Y direction of the antenna (1), as shown in figure-1 on both the opposite faces. In accordance to one of the preferred embodiments of the present invention the strips (4 and 5) make a same angle on both the opposite faces. In accordance to another preferred embodiment of the present invention the strips (4 and 5) make a different angle on both the opposite faces. According to a preferred embodiment of the present invention the strips (4 and 5) make an angle alpha with respect to the Y direction of the antenna (1) on one of the two opposite faces and minus alpha angle with respect to the Y direction of the antenna (1) on another opposite face. According to another preferred embodiment of the present invention said parallel, thin and closely placed strips (4 and 5) make an angle alpha with respect to the Y direction of the antenna (1) on both the opposite faces. Further, in accordance to another preferred embodiment of this invention the said parallel, thin and closely placed strips (4 and 5) make minus alpha angle with respect to the Y direction of the antenna (1) on said opposite faces. However, the present invention is not limited by having the strips (4 and 5) forming alpha or minus alpha angle on one face and minus alpha or alpha angle on opposite face.
The main dielectric substrate (2) is preferably connected to a coaxial connector (6). The input signal to the antenna (1) is generaly fed through a coaxial connector (6).
The said pattern of alternate metallic (4) and non-metallic (5) strips, in accordance to one of the preferred embodiments of the present invention is preferably partly coated with aluminium (7), partly uncoated (8), partly has single coating of the microwave absorber (9) and partly has double coating of the microwave absorber (10) [refer figure-2]. However, the presently disclosed antenna of the present invention is not limited to such an arrangement of pattern partly coated with aluminium (7), partly uncoated (8), partly having single coating of the microwave absorber (9) and partly having double coating of the microwave absorber (10).
In accordance to another preferred embodiment of this invention, the said pattern
of alternate metallic (4) and non-metallic (5) strips is partly coated with aluminium (7) and partly uncoated (8) [refer figure-3].
Further in accordance to another preferred embodiment of the present invention the said pattern of alternate metallic (4) and non-metallic (5) strips is partly coated with aluminium (7) and partly uncoated (8) and partly coated with single coating of microwave absorber (9) [refer figure-4].
Still further in accordance to another preferred embodiment of the present invention the said pattern of alternate metallic (4) and non-metallic (5) strips is partly coated with aluminium (7) and partly uncoated (8) and partly coated with double coating of microwave absorber (10) [refer figure-5].
In accordance to the preferred embodiment of the present invention the said pattern of alternate metallic (4) and non-metallic (5) strips is preferably partly coated with aluminium (7) and partly uncoated (8) [refer figure-3]. The antenna, as described and disclosed herein above, in the present invention preferably has single coating of microwave absorber (9) and/or double coating of microwave absorber (10) [refer figure 2, 4 and 5].
Therefore, from the foregoing description it is obvious that the said pattern of the presently disclosed antenna (1) on the dielectric substrate (2) may have various possible combinations of coating with aluminium (7), and/or single coating of the microwave absorber (9) and/or double coating of the microwave absorber (10) and/or partly uncoated (8) substrate.
The antenna fabricated in accordance to one of the preferred embodiments of this invention radiates two beams, symmetrically inclined with respect to the YZ-plane, as shown in figure-1. The output signals, that is the radiated beams are circularly polarised signals. The antenna can also be used for receiving the circularly signals when properly oriented with respect to the direction of the arrival of the signal, thus providing an
advantage of being suitable as transmitting as well as receiving antenna without any change in the configuration.
The present invention has been described with the help of accompanying figures, which are not intended to limit the scope of the present invention. The antenna, as described and disclosed herein above, definitely overcomes some of the disadvantages and drawbacks of the prior art and sill has advantages as described herein above.




WE CLAIM;
1. A flat antenna for communicating circularly polarised signals in wireless,
satellite communication systems etc. comprising a thin, flat dielectric substrate,
preferably rectangular in shape having a first surface and a second surface provided
with a pattern formed by conducting metallic sheet (3) on each of first and the second
surface of said substrate, said pattern comprising thin and closely placed strips (4 and
5) of conducting metallic sheet (4) separated by thin strip of non-metallic strip (5),
preferably of said dielectric substrate itself, said pattern being optionally coated
partially with a coating selected from aluminium (7), single coating of a microwave
absorber (9) double coating of microwave absorber (10) or a combination thereof.
2. A flat antenna as claimed in claim 1 wherein said strips are parallel to one
another.
3. A flat antenna as claimed in claim 1 or 2 wherein said pattern on said first
surface is similar to said pattern on said second surface of said substrate.
4. A flat antenna as claimed in any of the claims 1 to 3 wherein said strips (4, 5)
make an acute angle with respect to the longitudinal axis (y) of said antenna both on
said first surface and second surface.
5. A flat antenna as claimed in any of the claims 1 to 4 wherein said angle on the
first surface is equal to that on the second surface.
6. A flat antenna as claimed in any of the claims 1 to 5 wherein said angle on the
first surface is not equal to said angle on the second surface.
7. A flat antenna as claimed in any of the claims 1 to 6 wherein said said
respective angles on the first surface and the second surface are supplementary angles.
8. A flat antenna as claimed in any of the claims 1 to 7 wherein said pattern is
coated with at least one of the coatings such as partially coated with aluminium (7),

partially coated with single coating of microwave absorber (9), partially coated with double coating of microwave absorber (10) and the remaining portion is left uncoated.
9. A flat antenna as claimed in any of the claims 1 to 8 wherein said pattern is
partially coated with aluminium (7) and the remaining portion is left uncoated (8).
10. A flat antenna as claimed in any of the claims 1 to 9 wherein said pattern is
partially coated with aluminium (7), partially coated with single coating of microwave
absorber and the remaining portion is left uncoated (8).
11. A flat antenna as claimed in any of the claims 1 to 10 wherein said pattern is
partially coated with aluminium (7), partially coated with double coating of
microwave absorber and remaining portion is left uncoated (8).
12. A flat antenna for communicating circularly polarised signals substantially as
hereinbefore described with reference to the accompanying drawings.


Documents:

1202-del-1997-abstract.pdf

1202-DEL-1997-Claims.pdf

1202-del-1997-correspondence-others-po.pdf

1202-del-1997-correspondence-others.pdf

1202-del-1997-description (complete).pdf

1202-del-1997-drawings.pdf

1202-del-1997-form-1.pdf

1202-del-1997-form-13.pdf

1202-del-1997-form-19.pdf

1202-del-1997-form-2.pdf

1202-del-1997-form-26.pdf

1202-del-1997-form-3.pdf

1202-del-1997-form-5.pdf

1202-del-1997-form-6.pdf

1202-del-1997-petition-137.pdf


Patent Number 215319
Indian Patent Application Number 1202/DEL/1997
PG Journal Number 11/2008
Publication Date 14-Mar-2008
Grant Date 25-Feb-2008
Date of Filing 09-May-1997
Name of Patentee DEAN, INDUSTRIAL RESEARCH AND DEVELOPMENT
Applicant Address INDIAN INSTITUTE OF TECHNOLOGY DELHI, HAUZ KHAS NEW DELHI - 110 016, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 RAJESH PRABHAKAR BHAVE DEPARTMENT OF ELECTRICAL ENGINEERING, INDIAN INSTITUTE OF TECHNOLOGY DELHI, HAUZ KHAS NEW DELHI - 110 016, INDIA
2 SHEEL ADITYA DEPARTMENT OF ELECTRICAL ENGINEERING, INDIAN INSTITUTE OF TECHNOLOGY DELHI, HAUZ KHAS, NEW DELHI - 110 016, INDIA
PCT International Classification Number H01Q 21/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA