DESC:
TECHNICAL FIELD OF THE INVENTION

[0001] The present disclosure/invention relates generally to antennas and more particularly, to a shared aperture dual band dual function antenna.
BACKGROUND OF THE INVENTION

[0002] Generally, Modern Radar Systems have dual functions of search and track. The objective of the search radar is to detect the target within a predetermined volume whereas the objective of the track radar is to track the target and determine the position and direction of the target. Search Radars require a wider beam antenna to search a given volume in a short span of time. Track Radars on the other hand require a narrow beam antenna to perform the tracking and provide precise direction and location of the target to engage the onboard electronic counter systems.
[0003] The antenna requirement for search radar is different from that of track radar. Therefore, radars have separate antenna for each functions, a wide beam-width antenna for search operation and narrow beam-width for track operation. Such an arrangement leads to larger aperture and poor utilization of aperture leading to lower efficiencies. A shared aperture concept provides a compact solution for such search and track radars. Usually search radars operate in lower frequencies sub 6GHz and track radars operate in K-, K or Ka bands. Search radars being low frequency and wide beam can encompass the high frequency track radars.
[0004] The prior details of the above-mentioned concept are provided below:
[0005] One of the prior art discloses a shared aperture dual band micro-strip antenna with broadside radiation pattern at S band and squinted radiation pattern at Ka Band. The antennas are configured on a single substrate with a slot on the lower frequency radiating patch. A travelling wave high frequency patch is used as an antenna element for higher frequency.
[0006] Another prior art discloses a wideband open ended waveguide array encompassing two adjacent microwave bands. A diplexer is used to separate the received wideband signal into two frequency channels.
[0007] Further prior art discloses a dual broadband shared-aperture perforated patch antenna. This prior art antenna features dual broadband characteristics (S- and X-bands). The S-band part of the antenna utilizes the aperture resonance and three-section feed line to achieve a 26.5% bandwidth while the X-band part utilizes both aperture and stacked patch resonances to achieve a 25.6% bandwidth.
[0008] The prior art concepts on shared aperture can be broadly categorized into two areas:
1. Sharing of aperture of antennas where the frequency ratio is less than 3. For example, S band and X band, X band and Ka Band etc. In such disclosures interlacing of the radiators, parasitic radiators are possible approaches.
2. In case of frequency ratio greater than 3 (such as S and Ka), prior art discloses a method of positioning high frequency antenna on the lower frequency antenna.

[0009] Use of shared aperture antenna for frequency ratio close to 20 to 30 where interlacing of radiators is not possible. Also, placement of higher frequency antenna on lower frequency leads to poorer isolation and difficulty in forming arrays.
[0010] It may be noted that use of dielectric medium at high frequency leads to higher losses and therefore lower efficiencies. For Radar application where high frequencies are used for track operation low efficiency and therefore low gain leads to compromised radar performance. Therefore, use of micro-strip patch antenna and other PCB based antennas at higher frequencies (>30GHz) leads to poorer system performances.
[0011] It may also be noted that use of metal structure like waveguides lead to lower losses, but such structures are bulky when one operates them at lower frequencies (<3 GHz).
[0012] Known in the art is shared aperture antenna having PCB medium for both operating at higher frequency spacing. It is also known in prior art where waveguides are interlaced with PCB medium (patch antenna) to create a shared aperture at lower frequency spacing.
[0013] Therefore, there is a need in the art with a shared aperture dual band dual function antenna to solve the above-mentioned limitations.
SUMMARY OF THE INVENTION

[0014] An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below.
[0015] Accordingly, in one aspect of the present invention relates to a shared aperture dual band antenna (10). The antenna (10) comprising at least one first section (11), wherein the first section (11) is formed from a plurality of wideband radiating apertures and a plurality of feed structures, at least one second section (12), wherein the second section is formed from a plurality of L shaped wideband radiating apertures and a plurality of metallic wells and at least one third section (13) at a center of the shared aperture antenna, wherein the third section is a hollow circular or oval structure forming a provision for laser beam. The first section (11) forms a right angle with the second section (12).
[0016] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0017] The detailed description is described with reference to the accompanying figures.
[0018] Figure 1 shows a top view of a preferred example embodiment of the shared aperture antenna according to an exemplary implementation of the present disclosure/ invention.
[0019] Figure 2 shows a side view of a preferred example embodiment of the shared aperture antenna according to an exemplary implementation of the present disclosure/invention.
[0020] Figure 3 exemplifies in detail the first section (11) as per figure 2 according to an exemplary implementation of the present disclosure/invention.
[0021] Figure 4 exemplifies in detail the second section (12) as per figure 2 according to an exemplary implementation of the present disclosure/invention.
[0022] Figure 5 shows the radiation pattern of the high frequency aperture in isolated condition (F1) and in shared aperture condition (F2) according to an exemplary implementation of the present disclosure/invention.
[0023] Figure 6 shows the radiation pattern of the low frequency aperture in isolated condition (F3) and in shared aperture condition (F4) according to an exemplary implementation of the present disclosure/invention.
[0024] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative methods embodying the principles of the present disclosure. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
[0026] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
[0027] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.
[0028] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
[0029] Figures discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged communications system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element.
[0030] In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present disclosure. It will be apparent, however, to one skilled in the art that the present disclosure may be practiced without these details. One skilled in the art will recognize that embodiments of the present disclosure, some of which are described below, may be incorporated into a number of systems.
[0031] However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the presently disclosure and are meant to avoid obscuring of the presently disclosure.
[0032] It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.
[0033] Various embodiments of the shared aperture dual band antenna are further described with reference to FIG. 1 to FIG. 6.
[0034] The present invention discloses a shared aperture dual band antenna, in which at least some embodiments of the present disclosure can be implemented. Although the shared aperture dual band antenna (10) is depicted to include one or a few components arranged in a particular arrangement in the present disclosure, it should not be taken to limit the scope of the present disclosure.
[0035] The shared aperture dual band antenna (10) is hereinafter interchangeably referred to as “shared aperture antenna (10)”, “dual band antenna (10)”, “antenna (10)”.
[0036] The present invention provides a Shared Aperture Antenna (10) with dual band and large frequency ratio is disclosed. The shared antenna system consists of High frequency antenna aperture, Low frequency antenna aperture and a provision for laser beam. The High frequency antenna aperture may include plurality of wideband square or rectangular radiating and feeding aperture. The High frequency antenna aperture may be formed in a dual groove fashion. The Low frequency antenna aperture may be formed from L shaped metal structure and metal choke well. An integrated laser beam provision is also disclosed.
The objective of the present invention is as follows:
[0037] The present invention provides a shared aperture for dual band antenna with frequencies separated by a large ratio especially suitable to be used in search and track radar.
[0038] The present invention provides the shared aperture antenna to have high efficiency and light weight.
[0039] The shared aperture antenna has a provision using laser beam for jamming application at the center of the disclosed antenna.
[0040] The shared aperture provides simultaneous operation of dual band electronics with minimal interference impact.
[0041] The shared aperture providing superior performance for high frequency of operation in terms of high power, low loss, high gain which are essential requirements for long radar range requirements.
[0042] In one embodiment, the present invention provides a shared aperture antenna in dual band for dual operation with a large frequency ratio.
[0043] In one embodiment, the present invention provides a novel shared aperture antenna wherein the sharing apertures provides an improved performance when compared to their stand-alone isolated performances. The antenna formed for the high frequency aperture provides a dual groove mechanism for creation of high impedance path for the lateral waves from the low frequency aperture. The antenna formed for the low frequency aperture provides a baffle action and a choking action for improving the radiation performances of the high frequency aperture and also improving interferences among the shared aperture antennas.
[0044] In one embodiment, the present invention provides a shared aperture antenna for radar comprises of: High frequency aperture antenna, Low frequency aperture antenna, a provision for Laser beam or any other electronic counter measure at the center of the shared aperture. The said High frequency aperture antenna is formed from plurality of square or rectangular wideband radiating aperture and feed structures. The said Low frequency aperture antenna is formed from plurality of L shaped wideband radiating aperture and metallic well. The said provision for laser beam may be formed from hollow circular or oval structure.
[0045] In one embodiment, the high frequency aperture antenna is formed from dual groove wide band radiating and feeding metal structure. The dimension of the said dual groove structure is optimized/adjustable for creating a high impedance layer for the low frequency aperture antenna.
[0046] In one embodiment, the low frequency aperture antenna is formed from an L shaped wide band radiating metal structure and a metal choke well. The dimension of the said metal choke well structure is optimized/adjustable for improving the interferences from high frequency antenna aperture.
[0047] Figure 1 shows a top view of a preferred example embodiment of the shared aperture antenna according to an exemplary implementation of the present disclosure/ invention.
[0048] The figure shows a top view of a preferred example embodiment of the shared aperture antenna of the present invention. The shared aperture antenna (10) consists of three sections. In one embodiment, the present invention discloses the shared aperture dual band antenna (10). The antenna (10) comprising: at least one first section (11), wherein the first section (11) is formed from a plurality of wideband radiating apertures and a plurality of feed structures, at least one second section (12), wherein the second section (12) is formed from a plurality of L shaped wideband radiating apertures and a plurality of metallic wells and at least one third section (13) at a center of the shared aperture antenna, wherein the third section is a hollow circular or oval structure forming a provision for laser beam. The first section (11) forms a right angle with the second section (12).
[0049] The first section (11) forms the high frequency aperture which may be used for performing the track operation of Radar. The second section (12) forms the low frequency aperture which may be used for search operation of Radar. The third section (13) forms the provision for integrating the laser beam or any other as required by jamming for electronic counter measure.
[0050] Figure 2 shows a side view of a preferred example embodiment of the shared aperture antenna according to an exemplary implementation of the present disclosure/invention.
[0051] The figure shows a side view of a preferred example embodiment of the shared aperture antenna of the present invention. The first section (11) is a high frequency aperture antenna (11), each wideband radiating aperture is a dual groove (D1, D2) wide band radiating aperture, and each feed structure is a metal feeding structure. The first section (11) forms a right angle with the second section (12). Such a scheme provides two advantages.
[0052] The first advantage is with respect to the radiation from the high frequency section. The second section (12) acts like a baffle to the radiated wave from the first section (11). Such a baffle helps in reducing the far offside lobes of the high frequency antenna thereby improving the overall performance of the radar. The second section (12) also acts as a beam narrowing structure for the radiated wave from the first section (11) which helps in achieving a narrower pencil beam from less number of elements.
[0053] The second advantage is with respect to separation of the plane of radiation of the shared aperture antenna. The plane of radiation of lower frequency antenna (12) is at an optimal height H from the plane of radiation of higher frequency antenna (11). Such a scheme of placement helps in reducing the band-to-band interferences thereby improving the near field isolation of the overall shared aperture antenna.
[0054] Figure 3 exemplifies in detail the first section (11) as per figure 1 according to an exemplary implementation of the present disclosure/invention.
[0055] The figure exemplifies in detail the first section (11) as per figure 1. The high frequency antenna aperture (11) consists of plurality of subsections (110) and (120). The subsection (110) forms the wide band radiating apertures tuned to operate at a high frequency of operation in K or Ka band. The wideband radiating apertures are formed from square or rectangular shaped metal structures. The subsection (120) forms the feed structure tuned to operate at a high frequency of operation in K or Ka band.
[0056] Such apertures are formed in such a way that any wave impinging from lateral direction i.e., from the low frequency antenna (12) is attenuated by the dual grooves D1 and D2 of the radiating apertures. The dimensions of the dual groove structures (D1, D2) may be adjustable. The scheme of dual groove structure helps in creating a high impedance path for the lateral waves from the low frequency radiation. Therefore, such a scheme helps in improving band to band isolation for the shared aperture antenna system. It also helps in improving the mutual coupling among antenna elements for low frequency structure (12).
[0057] Figure 4 exemplifies in detail the second section (12) as per figure 2 according to an exemplary implementation of the present disclosure/invention.
[0058] The figure exemplifies in detail the second section (12) as per figure 2. The low frequency antenna aperture (12) consists of plurality of subsections (210), (220), (230) and (240). The subsection (210) forms the wide band radiating aperture tuned to operate at a low frequency of operation in L or C band. The wideband radiating apertures are formed from L shaped metal structures. Such metal structures can be formed either from metal blocks or printed on PCBs. The length E1 and E2 of subsection (210) is optimally chosen to improve the radiated performance of low frequency response as well as act as an optimal baffle for the high frequency response. The dimensions/length (E1, E2) of the metallic choke well structures may be adjustable. The subsection (220) forms the metallic well which is at the plane of radiation of high frequency aperture antenna (11). These metallic well acts as a choke for the lateral waves generated from the high frequency aperture antenna (11). Such a scheme therefore helps in improving the interferences among the shared aperture antennas. The depth of the well E2 should be carefully chosen so as to act as a choke for the lateral waves from the high frequency aperture without disturbing the low frequency response.
[0059] The subsection (230) forms the feed mechanism for the low frequency aperture antenna (12). The feed may be formed from a coaxial cable or connector. The subsection (240) performs the dual role of self-interferences cancellation as well as holding mechanism for the low frequency aperture antenna. The subsection (240) may be formed from L shaped metal structure with screw provision.
[0060] The second section (12) provides a baffle action and a choking action for improving the radiation performances of the first section (11) and also improving interferences within the shared aperture antenna.
[0061] Figure 5 shows the radiation pattern of the high frequency aperture in isolated condition (F1) and in shared aperture condition (F2) according to an exemplary implementation of the present disclosure/invention.
[0062] The figure shows the radiation pattern of the high frequency aperture in isolated condition (F1) and in shared aperture condition (F2). It may be noted that the pattern in high frequency is not disturbed in shared aperture environment. As discussed above the high frequency antenna in shared aperture condition provides better far off side lobe levels which might be attributed to the baffle action and the presence of the choking well of the low frequency aperture.
[0063] Figure 6 shows the radiation pattern of the low frequency aperture in isolated condition (F3) and in shared aperture condition (F4) according to an exemplary implementation of the present disclosure/invention.
[0064] The figure shows the radiation pattern of the low frequency aperture in isolated condition (F3) and in shared aperture condition (F4). It may be noted that the pattern in low frequency is not disturbed in shared aperture environment. As discussed above the low frequency antenna in shared aperture condition provides better first side lobe levels which might be attributed to the improvement in the mutual coupling among the low frequency antennas due to the high impedance action of the dual grooves of the high frequency aperture antenna.
[0065] The various embodiments described above are specific examples of a single broader invention. Any modifications, alterations or the equivalents of the above-mentioned embodiments are pertaining to the same invention as long as they are not falling beyond the scope of the invention as defined by the appended claims. It will be apparent to a person skilled in the art that the shared aperture dual band dual function antenna may be provided using some or many of the above-mentioned features or components without departing from the scope of the invention. It will be also apparent to a skilled person that the embodiments described above are specific examples of a single broader invention which may have greater scope than any of the singular descriptions taught. There may be many alterations made in the invention without departing from the spirit and scope of the invention.
[0066] Figures are merely representational and are not drawn to scale. Certain portions thereof may be exaggerated, while others may be minimized. Figures illustrate various embodiments of the invention that can be understood and appropriately carried out by those of ordinary skill in the art.
[0067] In the foregoing detailed description of embodiments of the invention, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby incorporated into the detailed description of embodiments of the invention, with each claim standing on its own as a separate embodiment.
[0068] It is understood that the above description is intended to be illustrative, and not restrictive. It is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined in the appended claims. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein,” respectively.
,CLAIMS:
1. A shared aperture dual band antenna (10), the antenna (10) comprising:
at least one first section (11), wherein the first section (11) is formed from a plurality of wideband radiating apertures and a plurality of feed structures;
at least one second section (12), wherein the second section is formed from a plurality of L shaped wideband radiating apertures and a plurality of metallic wells; and
at least one third section (13) at a center of the shared aperture antenna, wherein the third section is a hollow circular or oval structure forming a provision for laser beam.

2. The antenna as claimed in claim 1, wherein the first section (11) forms a right angle with the second section (12).

3. The antenna as claimed in claim 1, wherein the first section (11) is a high frequency aperture antenna (11), each wideband radiating aperture is a dual groove (D1, D2) wide band radiating aperture, and each feed structure is a metal feeding structure.

4. The antenna as claimed in claim 3, wherein the first section (11) comprises plurality of subsections (110) and (120), where the subsection (110) forms the wide band radiating apertures tuned to operate at a high frequency of operation and the subsection (120) forms the feeding metal structures tuned to operate at a high frequency of operation, such that any lateral wave impinging from the second section (12) is attenuated by the dual grooves (D1 and D2) of the radiating apertures.

5. The antenna as claimed in claim 4, wherein the wideband radiating apertures comprise square wideband radiating apertures or rectangular wideband radiating apertures.

6. The antenna as claimed in claim 1, wherein the second section (12) is a low frequency aperture antenna (12), each L shaped wideband radiating aperture is a L-shaped wide band radiating metal structure and each metallic well is a metallic choke well.

7. The antenna as claimed in claim 6, wherein the second section (12) comprises plurality of subsections (210), (220), (230) and (240), where the subsection (210) forms the wide band radiating apertures tuned to operate at a low frequency of operation, the subsection (220) forms the metallic wells which is at a plane of radiation of first section (11) and acts as a choke for lateral waves generated from the first section (11), the subsection (230) forms a feed mechanism for the second section (12) and the subsection (240) is formed from a L shaped metal structure with screw provision which performs dual role of self-interference cancellation and a holding mechanism for the second section (12).

8. The antenna as claimed in claim 1, wherein the second section (12) acts as a baffle to a radiated wave from the first section (11) and acts as a beam narrowing structure for the radiated wave from the first section (11), for achieving a narrow pencil beam.

9. The antenna as claimed in claim 1, wherein a plane of radiation of the second section (12) is at an optimal height H from a plane of radiation of the first section (11).

10. The antenna as claimed in claim 1, wherein the second section (12) provides a baffle action and a choking action for improving the radiation performances of the first section (11) and also improving interferences within the shared aperture antenna.