DESC:FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

Title: A LIGHT-WEIGHT HIGH GAIN OMNI ANTENNA FOR MULTIBAND APPLICATIONS

APPLICANT DETAILS:
(a) NAME: BHARAT ELECTRONICS LIMITED
(b) NATIONALITY: Indian
(c) ADDRESS: Outer Ring Road, Nagavara, Bangalore 560045, Karnataka, India

PREAMBLE TO THE DESCRIPTION:
The following specification (particularly) describes the nature of the invention (and the manner in which it is to be performed):

A LIGHT-WEIGHT HIGH GAIN OMNI ANTENNA FOR MULTIBAND APPLICATIONS

FIELD OF INVENTION:
The present disclosure relates to communication systems. The disclosure, more particularly, relates to a light-weight high gain omni antenna for multiband applications.

BACKGROUND OF THE INVENTION:
The following background discussion includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication expressly or implicitly
Generally, Omni antennas exhibit wide band properties with average gain in the range of -10 to 2 dBi. Multi band high gain omni antennas are critical for reduction of cost, size and complexity of RF front end of a communication system in which very little work has been done so far. The prior arts related to this field are listed below.
US7064729B2 discloses an Antenna with radome has a linear array of driven elements and a linear second array of driven elements & a linear third array of parasitic elements aligned in three parallel planes. Dual band of operation with centre frequencies 850 MHz and 1900 MHz and Omni directional pattern. Details about Bandwidth, Gain achieved and dimensions of antenna are not provided. Based on the literature survey, these antennas are having very low gain in the order of -10 to 2 dBi over the bands.
WO 2010/077574 A2 discloses a printed antenna, which includes a radiating portion of copper wire with bends and power feed portion. This particular antenna is operating in frequency band of 2.4 – 2.5 GHz and from 4.9 – 5.875 GHz. Highest Gain achieved in first band is 5.1 dBi with out of roundness = 2.3 dBi (min. gain 2.8 dBi) and in second band is 4.7 dBi with out of roundness = 2.7 dBi (min. gain 2.0 dBi). Dimensions of the antenna are 132*21*0.8 mm3. Details are not provided about the radome and fixing of the antenna. The literature lacks the information on the performance of the antenna with radome.
CN107634322A discloses a double frequency high-gain Omni-directional antenna. This particular antenna is operating in frequency band of 0.84-0.96 GHz and from 1.71-2.17 GHz (VSWR< 2.32). Gain achieved in first band is in range of 4-5 dBi and in second band is 5-6.5 dBi with out of roundness = 1.23 dBi. The minimum gain is 1.8dBi and 3.77 dBi. Dimensions of the antenna are 1.03*?L*0.106* ?L. Details are not provided about the radome and fixing of the antenna. The literature lacks the information on the performance of the antenna with radome.
MICROWAVE JOURNAL 21 Dec 2015 discloses antenna with radome is operating in frequency band of 1.089-1.091 (VSWR< 1.5). Gain achieved in 5.5 dBi with Omni directional pattern. Dimensions of the antenna are 693.42 mm (H)*51.18 mm (D) and weight is 0.9 Kg.
Therefore, there is a need for an invention which provides a light-weight high gain omni antenna for multiband applications. to achieve the above objective.

OBJECTIVES OF THE INVENTION:
The primary object of the present invention is to overcome the problem stated in the prior art.
Another object of the present invention provides a light-weight high gain omni antenna for multiband applications.

SUMMARY OF THE INVENTION:
The present invention provides a light-weight high gain omni antenna comprising:
plurality of stack of cross-linked resonators, where at resonating frequency all resonators radiate constructively; and
a patch is etched on a substrate for stacking multiple patches, where plurality of screws and nuts are providing support to multiple patches and a thin wall wide band radome mounted thereon;
wherein a stack up cross-linked resonators are configured to achieve higher gain in the desired frequency ranges, where the resonator patch radiators are fed in such a way that all resonator patches radiate constructively at resonating frequency, thus providing higher gain, where an enhanced frequency band is achieved by adding an capacitance to the patch element.
In an embodiment, the gain is controlled by increasing the number of stacked resonator patches.
In an embodiment, the dual band omni antenna operates in the frequency range of 0.808 – 0.888 GHz and 1.038 - 1.258 GHz with VSWR <2.
In an embodiment, the low VSWR in dual bands is achieved through innovative design of CPW Cross Couple Fed Antenna.
In an embodiment, the high gain is achieved in both operating bands with peak gain of 4.96 dBi in first band and 6.09 dBi in second band through stacking of patches in a particular fashion.
In an embodiment, the roundness of radiation pattern less than 0.8 dB in first band and less than 0.3 dBi in second band which is controlled by optimizing thickness of substrate.
In an embodiment, designed with printed PCB antenna to achieve Size and weight reduction of ~ 30 % when compared to the similar antennas.(Ref: prior art 4). , the proposed antenna cost is reduced by 30%, by using printed circuit design and thus leads to less complexity in fabrication
In an embodiment, the supporting antenna structures to complement the performance of antenna, in particular frequency band and gain.
In an embodiment, radome is designed to avoid damage to the antenna against all terrain environments without much distortion in EM performance.
In an embodiment, 14.9.Gain can be increased further increased just by increasing number of stacked resonators.

DETAILED DESCRIPTION OF DRAWINGS:
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of their scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings in which:
Fig. 1: illustrates a 3D Antenna evolved from COCO (Coaxial Collinear) antenna.
Fig. 2: illustrates a design of CPW cross-coupled printed antenna.
Fig. 3: illustrates respective results of S11.
Fig. 4: illustrates a radiation pattern in operating bands.
Fig. 5: illustrates a simulated result of S11.
Fig. 6: illustrates radiation pattern in operating bands.
Fig. 7: illustrates radiation pattern in operating bands
Fig. 8: illustrates VSWR graph
Fig. 9: illustrates radiation pattern in operating bands

DETAILED DESCRIPTION:
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
The terms “comprises”, “comprising”, “includes”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or method.
Identification Friend-or-Foe (IFF) is a secure aircraft identification system that identifies friend and hostile aircrafts and to determine their bearing and range from the interrogator. An IFF system is a two-channel system, using the 1030 MHz band for interrogating signals and the 1090 MHz band for receiving response signalsIt should withstand the adverse environmental conditions. UHF Band ranges from 300 MHz- 3GHz. In order to achieve better receiving capability IFF Receiving antenna should be highly sensitive and have omnidirectional pattern operating in their respective frequency bands.
A coplanar waveguide (CPW) cross-coupling-fed antenna broad with radiant load which is evolved from COCO Antenna is designed. Designed antenna is 2D replica of COCO Antenna. It works as a monopole Antenna. Generally Omni directional antennas working in UHF & L-band have lesser gain in the range of -10 to 2 dBi. In this design Antenna gain is improved by adopting stack of cross linked resonators. At resonating frequency all resonators radiate constructively.
In one embodiment, a Light Weight Dual Band High Gain Omni antenna for multi band applications in which a patch is etched on a substrate in a particular fashion as of stacking of multiple patches, placement of mounting screws and nuts for providing support and thin wall wide band radome.
In another embodiment, Dual Band omni antenna operates in the frequency range of 0.808 – 0.888 GHz and 1.038 - 1.258 GHz with VSWR <2.
In another embodiment, low VSWR in dual bands is achieved through innovative design of CPW Cross Couple Fed Antenna.
In an embodiment, high gain is achieved in both operating bands with peak gain of 4.96 dBi in first band and 6.09 dBi in second band through stacking of patches in a particular fashion.
In another embodiment, the roundness of radiation pattern less than 0.8 dB in first band and less than 0.3 dBi in second band which is controlled by optimizing thickness of substrate.
In another embodiment, printed PCB antenna to achieve weight reduction of 33.33 % when compared to the similar antennas.
In another embodiment, designed the supporting antenna structures to complement the performance of antenna, in particular frequency band and gain.
In another embodiment, the proposed antenna cost is reduced by 30%, by using printed circuit design and thus leads to less complexity in fabrication.
In an advantageous embodiment, reduction in size is achieved by 31.3 % which is calculated with respect to lower frequency of operation.
In an advantageous embodiment, radome is designed to avoid damage to the antenna against all terrain environments without much distortion in EM performance.
In an advantageous embodiment, same design technique can be scaled for other frequencies also.
In an advantageous embodiment, gain can be increased further increased just by increasing number of stacked resonators.
The proposed Antenna operating in dual bands with high gain is etched on substrate material. The proposed Antenna does not exhibit distortion in radiation patterns and VSWR due to mechanical fitments like base plate, set of screws, fasteners, radome etc. All weather rugged design to withstand all environmental conditions. A stack up of ?/2 resonators are used to achieve higher gain in the desired frequency ranges. Resonator patch radiators are added and fed in such a way that all resonator patches radiate constructively at resonating frequency, thus providing higher gain. Enhanced frequency band is achieved by adding an extra capacitance to patch element. Frequency Band of operation is varied by varying length of resonator patches and value of capacitance. Gain is fully controlled by increasing the number of stacked resonator patches, which is unique design in the field of multi-band antennas. Reduction of size and cost of the antenna by 31.3% and 30% respectively is achieved by using CPW Cross Couple fed Printed Antenna with Capacitive Loading. A simple design with less material consuming and environmental friendly.
Referring to figure 1, 100 is evolved from COCO (Coaxial Collinear) antenna whereas COCO antenna is 3D structure. CPW cross coupled is a 2D replica of COCO antenna.
CPW cross-coupled printed antenna design is shown in figure 2 and it is designed on 201.The thickness of 201 is chosen in such a way to cut down dielectric loss and to improve the roundness of radiation pattern.
Entire geometry can be divided into two regions. They are 203 and 204. When current is fed from the bottom, it flows along the cross-linked transmission lines, establishing a current distribution on the transmission line. Such that current in 205 and 206 are fed 180° out of phase. Each 207 is of length ?g/2 which radiates at resonant frequency. So, any two cross-linked 207 differ by 180° in space and direct fed or couple fed by 180° out of phase. Hence at resonant frequency all 207 are in phase and radiate constructively which contributes to enhancement of gain. Resonant frequency of 100 can be determined by formula.
f=c/(2l_ivE_e )
At end of 203, 203 is connected to 204, establishing a current distribution on the 204. It is similar phenomenon as antenna is connected to a matched load on the terminal for maximum transmission. 204 and two adjacent 208 on left and right behaves as a monopole antenna and radiate into free space. Simulation model of initial design is shown in figure 2 and respective results of S11 and radiation pattern are shown in figure 3 & 4a. From results, it can be observed that it is operating in the range of frequencies from 1.23 – 1.30 GHz and gain at 1.3 GHz is 4.95 dBi with out of roundness less than 1.5 dBi.
Later Simulation is carried out by adding metal holder and simulated and model is simulated and respective results of S11 and radiation pattern are also shown in figure 3 & 4b. From the results it is observed that gain is decreased at resonating frequency. This decrement in gain is due to obstruction of radiation of lower 206 by metal holder, as all resonators are contributing for higher gain by radiating in phase at resonating frequency. This problem is solved by extending the length of 201, 205 & 206. Some optimisation in length is required such that all resonators are in phase. Some extended portion does not contribute to radiation as it is obstructed by 301. Initial model of 101 with extended length is simulated and its respective results of S11 and radiation pattern are shown in fig 3 &4c.
As length of 100 is more to withstand vibrations metal fixtures are used to hold PCB in place at the back side of PCB as shown in fig 7 and simulated results of S11 and radiation pattern in operating bands are shown in figures 5 & 6. From results it can be concluded that metal fixtures are adding any extra capacitance because of which operating frequency is shifted to lower side i-e 0.75-0.80 GHz with Omni gain pattern gain of 3.23dBi with out of roundness less than 1 dBi. Another resonance is obtained from 1.40-1.46 GHz with distorted pattern. As it quiet away from designed frequency it is deviated from Omni pattern behaviour. To obtain omnidirectional dual band some reduction in added capacitance is required it can be achieved by adding same amount of capacitance in series so that overall capacitance can be halved. This is done by adding metal fixtures of same dimensions on other side of the PCB as shown in fig 7 and simulated results of S11 and radiation pattern in operating bands are shown in figure 5 & 7. From results it can be observed omnidirectional dual band are obtained. First operating band is from 1.07 – 1.17 GHz with omni pattern gain of 5.8 dBi with out of roundness less than 0.5 dBi and second operating band is from 1.28 – 1.38 GHz with an omni gain of 5.68 dBi with out of roundness less than 1dBi. Hence by playing with the dimensions of metal fixtures or by varying capacitance operating bands of frequencies can be changed further.
Referring to figures 8 and 9, optimisation in dimensions leads to obtaining dual band Omni directional antenna. First band is operating in UHF band from 0.808 GHz – 0.888 GHz and second is operating in L-band from 1.038 GHz-1.258 GHz.It is operating in the frequency band from 0.808-0.888 GHz with Omni pattern gain of 4.96 dBi without of roundness less than 0.8 dBi and from 1.038-1.258 GHz with Omni pattern gain of 6.09 dBi without of roundness less than 0.3 dBi.
The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the invention.
,CLAIMS:We Claim:

1. A light-weight high gain omni antenna comprising:
a) plurality of stack of cross-linked resonators, where at resonating frequency all resonators radiate constructively; and
b) a patch is etched on a substrate for stacking multiple patches, where plurality of screws and nuts are providing support to multiple patches and a thin wall wide band radome mounted thereon;
wherein a stack up cross-linked resonators are configured to achieve higher gain in the desired frequency ranges, where the resonator patch radiators are fed in such a way that all resonator patches radiate constructively at resonating frequency, thus providing higher gain, where an enhanced frequency band is achieved by adding an capacitance to the patch element.
2. The light-weight high gain omni antenna as claimed in claim 1, wherein the gain is controlled by increasing the number of stacked resonator patches.
3. The light-weight high gain omni antenna as claimed in claim 1, wherein the dual band omni antenna operates in the frequency range of 0.808 – 0.888 GHz and 1.038 - 1.258 GHz with VSWR <2.
4. The light-weight high gain omni antenna as claimed in claim 1, wherein the low VSWR in dual bands is achieved through innovative design of CPW Cross Couple Fed Antenna.
5. The light-weight high gain omni antenna as claimed in claim 1, wherein the high gain is achieved in both operating bands with peak gain of 4.96 dBi in first band and 6.09 dBi in second band through stacking of patches in a particular fashion.
6. The light-weight high gain omni antenna as claimed in claim 1, the roundness of radiation pattern less than 0.8 dB in first band and less than 0.3 dBi in second band which is controlled by optimizing thickness of substrate.
7. It is designed with printed PCB antenna to achieve Size and weight reduction of ~ 30 % when compared to the similar antennas.(Ref: prior art 4). , the proposed antenna cost is reduced by 30%, by using printed circuit design and thus leads to less complexity in fabrication.
8. Designed the supporting antenna structures to complement the performance of antenna, in particular frequency band and gain.
9. As claimed, radome is designed to avoid damage to the antenna against all terrain environments without much distortion in EM performance.
10. Gain can be increased further increased just by increasing number of stacked resonators.