FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION (See Section 10 and Rule 13)
Title of invention:
FLAT ANTENNA BASED REFLECT ARRAY SYSTEM AND WIDEBAND LINEAR TO CIRCULAR POLARIZATION CONVERSION THEREOF
Applicant
Tata Consultancy Services Limited A company Incorporated in India under the Companies Act, 1956
Having address:
Nirmal Building, 9th floor,
Nariman point, Mumbai 400021,
Maharashtra, India
Preamble to the description
The following specification particularly describes the invention and the manner in which it is to be performed.

TECHNICAL FIELD
[001] The disclosure herein generally relates to antenna based reflect array system, and, more particularly, to flat antenna based reflect array system and wideband linear to circular polarization conversion for the same.
BACKGROUND
[002] Communication terminals including very-small-aperture terminal (VSAT) and other wireless systems with antennas can be employed for a wide variety of applications to ensure communication even in very remote locations. Conventionally, parabolic antennas are used for VSAT applications. For example, at Ku- band frequency, a parabolic antenna with a dish diameter typically between 0.8m to 1.3m could be used. Manufacturing process of these antennas includes use of a thin film of electrically conductive metal on the reflector front surface to reflect radio frequency (RF) energy during antenna operation. Aluminum is commonly used as the electrically conductive metal and aluminum coating thicknesses ranging from 100 to 10000 A are applied to the parabolic antennas. However, at higher frequencies, more precise fabrication is required to ensure accuracy lying within λ/100 limit. Thus, the parabolic antennas are required to be manufactured with care. Further, state of the art methods require separate antenna design and manufacturing to achieve different design needs. Thus, each parabolic dish antenna is designed uniquely and manufactured as a single monolithic piece. Thus, cost and size of the antenna reflect array system is a concern with the conventional systems. Furthermore, the parabolic antennas are difficult to be mounted on top of vehicles.
SUMMARY
[003] Embodiments of the present disclosure present technological improvements as solutions to one or more of the above-mentioned technical problems recognized by the inventors in conventional systems. In an aspect, there is provided a flat antenna based reflect array system comprising: a dipole antenna positioned on a first substrate and cooperating with a Radio Frequency (RF) input to receive and transmit radio waves; a high impedance surface disposed at a

predetermined distance from the dipole antenna and configured to reflect the radio waves such that a wide band circularly polarized wave is obtained by conversion from linear to circular polarization, wherein the high impedance surface is characterized by: a second substrate that accommodates a plurality of S-shaped printed patches on a first surface and a conducting plate on an opposite surface, wherein the conducting plate is connected to a ground terminal and an air gap exists between the first substrate and the second substrate, each of the plurality of S-shaped printed patches and sides of the second substrate are separated by a predefined region, each of the plurality of S-shaped printed patches comprises two halves that are separated at a centre thereof by a surface mount capacitor, and a plurality of posts having a first end and a second end, positioned on opposite sides of the conducting plate, wherein the first end is coupled to a portion of a part of the two halves of each of the plurality of S-shaped printed patch and the second end is connected to the conducting plate; a BALUN device to transform a pair of unbalanced transmission lines to a pair of balanced transmission lines; and a controller unit in communication with the BALUN device, wherein the controller unit comprises: one or more data storage devices configured to store instructions; one or more communication interfaces; and one or more hardware processors operatively coupled to the one or more data storage devices via the one or more communication interfaces, wherein the one or more hardware processors are configured by the instructions to: obtain an optimized value for (i) length and shape of the dipole antenna, and (ii) the predetermined distanced between the dipole antenna in far field and the high impedance surface to achieve a wide band linear to circular polarization conversion; and determine a capacitance value through the surface mount capacitor that is used to shift operation frequency and tune bandwidth of the wide band linear to circular polarization conversion post-fabrication.
[004] In another aspect, there is provided a processor implemented method comprising the steps of: positioning, a dipole antenna on a first substrate and cooperating with a Radio Frequency (RF) input to receive and transmit radio waves; disposing, a high impedance surface at a predetermined distance from the dipole

antenna and configured to reflect the radio waves such that a wide band circularly polarized wave is obtained by conversion from linear to circular polarization, wherein the high impedance surface is characterized by: a second substrate that accommodates a plurality of S-shaped printed patches on a first surface and a conducting plate on an opposite surface, wherein the conducting plate is connected to a ground terminal and an air gap exists between the first substrate and the second substrate, each of the plurality of S-shaped printed patches and sides of the second substrate are separated by a predefined region, each of the plurality of S-shaped printed patches comprises two halves that are separated at a centre thereof by a surface mount capacitor, and a plurality of posts having a first end and a second end, positioned on opposite sides of the conducting plate, wherein the first end is coupled to a portion of a part of the two halves of each of the plurality of S-shaped printed patch and the second end is connected to the conducting plate; transforming, using a BALUN device, a pair of unbalanced transmission lines to a pair of balanced transmission lines; obtaining, via one or more hardware processors, an optimized value for (i) length and shape of the dipole antenna in far field and (ii) the predetermined distanced between the dipole antenna and the high impedance surface to achieve a wide band linear to circular polarization conversion; and determining, via the one or more hardware processors, a capacitance value through the surface mount capacitor that is used to shift operation frequency and tune bandwidth of the wide band linear to circular polarization conversion post-fabrication.
[005] In accordance with an embodiment of the present disclosure, the dipole antenna is characterized by: two half-wavelength L-bent shaped conducting elements that are separated by a predefined distance and positioned on the first substrate with each of the two half-wavelength L-bent shaped conducting elements having length along a X-axis and bent along a Y-axis in an XY plane of a Cartesian coordinate system; a feeding point disposed in a portion of the bent along the Y-axis of each of the two L-bent shaped conducting elements; and the pair of balanced transmission lines from the BALUN device that are connected to the feeding point

of each of the two L-bent shaped conducting elements by passing through the first substrate and the second substrate.
[006] In accordance with an embodiment of the present disclosure, the optimized value for (i) the length and the shape of the dipole antenna in the far field, and (ii) the predetermined distanced between the dipole antenna and the high impedance surface are obtained based on optimization of impedance bandwidth and circular polarization bandwidth.
[007] In accordance with an embodiment of the present disclosure, the optimized predetermined distance is 2 millimeter (mm).
[008] In accordance with an embodiment of the present disclosure, the flat antenna based reflect array system further comprising exhibiting functional modularity and providing an improved directivity upon being cascaded side by side.
[009] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[010] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles:
[011] FIG. 1 illustrates an exemplary block diagram of a flat antenna based reflect array system according to some embodiments of the present disclosure.
[012] FIG. 2A and FIG.2B illustrate an exemplary representation (Not to scale) of a top view and a side view, respectively of the flat antenna based reflect array system according to some embodiments of the present disclosure.
[013] FIG. 3A and FIG.3B illustrate an exemplary representation (Not to scale) of a top view and a side view, respectively of a S-shaped printed patch according to some embodiments of the present disclosure.
[014] FIG. 4A and FIG.4B illustrate an exemplary representation (Not to scale) of a top view and a side view, respectively of a dipole antenna in accordance with some embodiments of the present disclosure.

[015] FIG. 5 is an exemplary flow diagram illustrating a processor implemented method for wideband linear to circular polarization conversion of a flat antenna based reflect array system, in accordance with an embodiment of the present disclosure.
[016] FIG. 6A and FIG. 6B illustrate frequency and circular polarization bandwidths plots of the flat antenna based reflect array system for different values of capacitors.
[017] FIG.7 is a 2-Dimensional radiation pattern of the flat antenna based reflect array system according to some embodiments of the present disclosure.
[018] FIG.8 illustrates an example of cascaded flat antenna based reflect array systems for increased gain and improved directivity, according to some embodiments of the present disclosure.
DETAILED DESCRIPTION OF EMBODIMENTS [019] Exemplary embodiments are described with reference to the accompanying drawings. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, adaptations, and other implementations are possible without departing from the scope of the disclosed embodiments.
[020] Communications terminals including very-small-aperture terminal (VSAT) and other wireless systems with antennas can be employed for a wide variety of applications to ensure communication even in very remote locations. Conventionally, parabolic antennas are used for VSAT applications. For example, at Ku- band frequency, a parabolic antenna with a dish diameter typically between 0.8m to 1.3m could be used. Manufacturing process of these antennas includes use of a thin film of electrically conductive metal on the reflector front surface to reflect radio frequency (RF) energy during antenna operation. Aluminum is commonly used as the electrically conductive metal and aluminum coating thicknesses ranging from 100 to 10000 A are applied to the parabolic antennas. However, at higher

frequencies, more precise fabrication is required to ensure accuracy lying within λ/100 limit. Thus, the parabolic antennas are required to be manufactured with care. Further, state of the art methods require separate antenna design and manufacturing to achieve different design needs. For this purpose, each parabolic dish antenna is designed uniquely and manufactured as a single monolithic piece. Thus, cost and size of the antenna reflect array system is a concern with the conventional systems. Furthermore, the parabolic antennas are required to be mounted on top of vehicles.
[021] There is an emerging need to design a flat and high gain antenna for mounting on top of vehicles which are used as mobile earth stations. Conventionally, the antennas used are of parabolic dish and require complicated mounting facilities. Design of the parabolic dish antennas becomes even more complicated since they need to withstand high wind speed. Further, fabrication tolerances for the parabolic dish antennas dish antennas are high. Furthermore, cost and size of the antenna reflect array system is a concern with the conventional systems. However, with many more satellites getting launched. there is a need for modular antenna design and antennas at different frequencies and gains to meet the market requirements.
[022] The technical problem of simplifying the manufacturing process and making the antenna being amenable to be mounted to vehicles is addressed in the present disclosure by providing a flat antenna based reflect array system. The flat antenna based reflect array system provided in the present disclosure designs larger-sized antennas by an ensemble of basic functional modules and using a concept of Metasurface (described later in the description) that helps in significantly reducing cost of mass manufacturing and addresses the concern on the size of the antenna.
[023] In the context of the subject disclosure, definitions of certain expressions and their usage are as explained herein below.
• Metamaterial is an artificial structure consisting of periodic
inclusions or unit cells that show exotic properties. Precise geometry, size and orientation of the unit cell structures render them capable of manipulating electromagnetic waves such as blocking, absorbing, enhancing, or bending the electromagnetic (EM) waves. The metamaterial is primarily determined by physical

structures of subwavelength building blocks, which have inspired many applications such as cloaks, gradient index lenses, perfect absorbers, polarization rotators, and many other devices.
• Metasurface is a 2-Dimensional representation of the metamaterial with thickness less than operating wavelength. Essentially, it consists of a periodic arrangement of “unit cells” (dimension of each unit cell << a wavelength (λ) corresponding to a frequency of interest) printed on a Printed Circuit Board (PCB) material like Rogers RT-Duroid® 5880 (dielectric constant or relative permittivity = 2.2) or say Flame Retardant material (FR-4) (dielectric constant or relative permittivity = 4.4). Any substrate material may be chosen with a sole consideration that the substrate height is less than λ.
• Metasurface design is configured to manipulate the electromagnetic waves by arranging the artificial structures on a flat interface to engineer a phase profile, polarization, amplitude, and trajectory of the electromagnetic waves. Metasurface exhibits deep subwavelength thickness, low loss, and easy fabrication.
• High impedance surface is a thin resonant cavity synthesized by printing a periodic frequency selective surface (FSS) on top of a grounded dielectric slab. The high impedance surface exhibits a perfect magnetic conductor (PMC) condition within a fixed frequency range and are often referred to as artificial magnetic conductor (AMC). The high impedance surfaces are used in design of ultra-thin electromagnetic absorbers, low-profile antennas, Fabry-Perot or Leaky wave antennas, and to mitigate simultaneous switching noise (SSN) in PCB circuit.
• Polarization, for a time-harmonic wave, refers to a time-varying direction and relative magnitude of an electric field vector (E) at a fixed point in space. It is also described as a curve traced by head of the electric field vector as a function of time.
• The expressions ‘PCB’ and ‘substrate’ may be interchangeably used.
• The expressions x-axis, y-axis and z-axis may be interchangeably represented as X-axis, Y-axis and Z-axis respectively.
• φ and phi may be interchangeably used.

• θ and theta may be interchangeably used.
[024] Referring now to the drawings, and more particularly to FIG. 1 through FIG.8, where similar reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments and these embodiments are described in the context of the following exemplary system and/or method.
[025] Reference numerals of one or more components of the flat antenna based reflect array system as depicted in the FIG.1 are provided in Table 1 below for ease of description:
Table 1:

Sr.No. Component Reference numeral
1 Dipole antenna 102
2 First Substrate 104
3 Radio Frequency (RF) input 106
4 High impedance surface 108
5 BALUN device 110
6 Balanced transmission line 112
7 Controller unit 114
8 Data storage device/Memory 112A
9 Communication interface 112B
10 Hardware processor 112C
11 Second substrate 108A
12 S- shaped printed patch 108B
13 Conducting plate 108C
14 Predefined region 108D
15 Surface mount capacitor 108E
16 Post 108F
17 L-bent shaped conducting element 102A

18 feeding point 102B
[026] FIG. 1 illustrates an exemplary block diagram of a flat antenna based reflect array system 100 according to some embodiments of the present disclosure. In an embodiment, flat antenna based reflect array system 100 comprises a dipole antenna 102 positioned on a first substrate 104 and cooperating with a Radio Frequency (RF) input 106 to receive and transmit radio waves. In an embodiment, the first substrate is cuboidal shaped. In an embodiment, length, width and height of the first substrate is 15mm, 2.5mm and 0.5mm respectively. Communication signals like baseband signals when modulated are fed from the Radio Frequency (RF) input to the dipole antenna 102. FIG. 2A and FIG.2B illustrate an exemplary representation (Not to scale) of a top view and a side view, respectively of the flat antenna based reflect array system according to some embodiments of the present disclosure. The dimensions illustrated are representative of an exemplary embodiment and ∈r represents relative permittivity while tan δ represents dielectric loss tangent respectively.
[027] The flat antenna based reflect array system 100 further comprises a high impedance surface 108 disposed at a predetermined distance from the dipole antenna 102 and configured to reflect the radio waves such that a wide band circularly polarized wave is obtained by conversion from linear to circular polarization. In an embodiment, the high impedance surface is a form of the metasurface and square shaped. In an embodiment, the high impedance surface 108 is characterized by a second substrate 108A that accommodates a plurality of S-shaped printed patches 108B on a first surface and a conducting plate 108C on an opposite surface. In an embodiment, the conducting plate 106 is a metallic plate. In an embodiment, the conducting plate 108C is connected to a ground terminal and an air gap exists between the first substrate 104 and the second substrate 108A. The ground terminal may or may not be same as the ground terminal of the RF input 106. In an embodiment, the first substrate and the second substrate are made of an insulating material such as Polytetrafluoroethylene (PTFE) which is commercially available as Rogers RT-Duroid® 5880 (dielectric constant or relative permittivity

= 2.2). In an embodiment, the first and the second substrate could be same and different from each other. In other words, the high impedance surface (HIS) comprises of 4X4 array of unit cells, where each unit cell consists of an S-shaped printed patch 108B on the second substrate 108A. Top layer of the HIS is backed by a metallic ground plane with support of the second substrate in between.
[028] In an embodiment, each of the plurality of S-shaped printed patches 108B and sides of the second substrate 108A are separated by a predefined region 108D. Further, each of the plurality of S-shaped printed patches (108B) comprises two halves that are separated at a centre thereof by a surface mount capacitor 108E. The high impedance surface rests on a plurality of posts 110 positioned on opposite sides of the conducting plate 108C. Accordingly, in an embodiment, the high impedance surface 108 is further characterized by the plurality of posts 108F having a first end and a second end, positioned on opposite sides of the conducting plate 108C. In an embodiment, the post is metallic and cylindrical in shape with diameter of 0.6mm. In an embodiment, the first end of the plurality of posts is coupled to a portion of a part of the two halves of each of the plurality of S-shaped printed patch 108B and the second end is connected to the conducting plate 108C. The optimized high impedance surface is finalized after performing many parametric iterations on the dimensions and number of unit cells.
[029] FIG. 3A and FIG.3B illustrate an exemplary representation (Not to scale) of a top view and a side view, respectively of a S-shaped printed patch according to some embodiments of the present disclosure. The dimensions illustrated are representative of an exemplary embodiment. In current state of the arts, it is shown that a S-shaped unit cell backed by ground plane displays strong linear cross-polarization over a wide frequency band as well as potential for circular polarization over a narrow frequency band. However, state of the art systems discuss a combination of exciting antenna and the high impedance surface only without being evaluated. In the system of the present disclosure, it is observed that in order to obtain circular polarization, design of S-shaped printed patches require following modifications as shown in FIG. 3A:

1. Two halves of S-shaped printed patch are separated at centre by a suitable choice of capacitance value through the surface mount capacitor.
2. One half of the two halves parts of S-shaped printed patch as obtained in the previous step is plated through hole and shorted to background plane with a metallic cylindrical post of a given dimension.
[030] The flat antenna based reflect array system 100 further comprises a BALUN device 110 to transform a pair of unbalanced transmission lines to the pair of balanced transmission lines 112. In an embodiment, the dipole antenna 102 is characterized by two half-wavelength L-bent shaped conducting elements 102A that are separated by a predefined distance and positioned on the first substrate 104 with each of the two half-wavelength L-bent shaped conducting elements (102A) having length along a X-axis and bent along a Y-axis in an XY plane of a Cartesian coordinate system. In an embodiment, the predefined distance for separating the two half-wavelength L-bent shaped conducting elements 102A is 0.5mm. In an embodiment, the dipole antenna 102 is further characterized by a feeding point 102B disposed in a portion of the bent along the Y-axis of each of the two L-bent shaped conducting elements 102A and the pair of balanced transmission lines 112 from the BALUN device 110 that are connected to the feeding point 102B of each of the two L-bent shaped conducting elements 102A by passing through the first substrate 104 and the second substrate 108A. In other words, an external radio frequency signal is fed to the BALUN device 110 which transforms a pair of unbalanced transmission lines to a pair of balanced transmission lines 112. The pair of balanced transmission lines 112 pass through the second substrate and get connected to feeding points of the dipole antenna. FIG. 4A and FIG.4B illustrate an exemplary representation (Not to scale) of a top view and a side view, respectively of the dipole antenna in accordance with some embodiments of the present disclosure. The dimensions illustrated are representative of an exemplary embodiment.
[031] In the system of the present disclosure, a standard half wavelength dipole antenna is reshaped to an L-bent thereby easing connectivity to the pair of balanced transmission lines as shown in FIG. 2B. Additionally, a small 900 bent in

orthogonal direction (the dipole antenna length is along X axis whereas the bent is along Y axis) creates an asymmetry of antenna elevation beams for φ= 00 (along X axis) and φ= 900 (along Y axis). This asymmetry is used as design parameter in the present disclosure. It may be noted that a dipole antenna is a co-polarized antenna with theoretically no cross-polarized component. On the other hand, after reflection from the high impedance surface, a cross-polarized component is seen dominant, but strength of co-polarized component does not vanish. This indicates that there exists an asymmetry of two orthogonal far-field radiation patterns particularly so for off-zenith angles. Conventionally, this is circumvented by using a cross-dipole design (i.e., two half wavelength antennas at 900 to each other). However, the system of the present disclosure utilizes a standard half wavelength dipole antenna and incorporates a 900 bend. Extent of bend is further optimized.
[032] The flat antenna based reflect array system 100 further comprises a controller unit 114 that is in communication the BALUN device 110. The controller unit 114 further comprises one or more data storage devices or memory 114A configured to store instructions; one or more communication interfaces 114B; and one or more hardware processors 114C operatively coupled to the one or more data storage devices via the one or more communication interfaces 114B.
[033] The one or more hardware processors 114C can be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, graphics controllers, logic circuitries, and/or any devices that manipulate signals based on operational instructions. Among other capabilities, the processor(s) are configured to fetch and execute computer-readable instructions stored in the memory. In the context of the present disclosure, the expressions ‘processors’ and ‘hardware processors’ may be used interchangeably. In an embodiment, the one or more hardware processors 114C can be implemented in a variety of computing systems, such as laptop computers, notebooks, hand-held devices, workstations, mainframe computers, servers, a network cloud and the like.
[034] In an embodiment, the communication interface(s) or input/output (I/O) interface(s) 114B may include a variety of software and hardware interfaces,

for example, a web interface, a graphical user interface, and the like and can facilitate multiple communications within a wide variety of networks N/W and protocol types, including wired networks, for example, LAN, cable, etc., and wireless networks, such as WLAN, cellular, or satellite. In an embodiment, the I/O interface(s) can include one or more ports for connecting a number of devices to one another or to another server.
[035] The one or more data storage devices or memory 114A may include any computer-readable medium known in the art including, for example, volatile memory, such as static random access memory (SRAM) and dynamic random access memory (DRAM), and/or non-volatile memory, such as read only memory (ROM), erasable programmable ROM, flash memories, hard disks, optical disks, and magnetic tapes.
[036] In an embodiment, the one or more hardware processors 114C are configured by instructions to obtain an optimized value for (i) length and shape of the dipole antenna and (ii) the predetermined distanced between the dipole antenna in far field (102) and the high impedance surface (108) to achieve a wide band linear to circular polarization conversion.
[037] In the context of the present disclosure, the expressions ‘linear polarization’, ‘circular polarization’ and ‘wide band’ can be better understood by way of the following description provided as exemplary explanation.
[038] In an embodiment, linear polarization is said to be occurring in three cases as described below:
1. Case-I: If Ex = 0 and only Ey exists as E = a. Ey, then wave is said
to be linearly polarized in y-direction. Here, Ex represents electric field along X-axis and Ey represents electric field along Y-axis and Ey may be positive or negative. In other words, when electric field denoted by E is oriented along positive or negative y-direction at all times which implies that head of vector E traces out a line, hence it is called linear polarization. The electric field of a linearly polarized wave traveling in positive z-direction is expressed as a function of time and position as provided in equation 1 below:

Ey(z,t)= Ey0sin(ωt-βz) (1) where Ey0 denotes the amplitude of the linearly polarized wave Ey.
2. Case-II: A similar consideration holds for polarization in x-
direction. Endpoint of E moves in x-direction with time (i.e., the locus of the vector
head is a line), therefore as provided in equation 2 below:
Ex(z,t)= Ex0sin(ωt-βz) (2)
3. Case-III: If both Ex and Ey are present and have phase difference
then the resultant electric field is linear and has a direction dependent on relative magnitude of Ex and Ey. The angle made by this field vector with the X-axis is provided in equation 3 below:

(3)
Here, ϕ is constant with time.
In all the above cases, direction of resultant vector is constant with time, the head of the resultant vector E moves along a line and the wave is said to be linearly polarized.
[039] In an embodiment, the circular polarization is said to be occurring when superposition of two waves Ex and Ey having equal magnitudes (Ex0 = Ey0 ) and 900/2700 phase difference leads to the direction of the resultant electric vector E varying with time. In such cases, the head of the resultant electric vector E is traces out a circle as a function of time, and the wave is circularly polarized.
[040] In the context of present disclosure, the expression ‘wide band’ is illustrated based on fractional bandwidth of an antenna which indicates a measure of how wideband the antenna is. If the antenna operates at center frequency fc between lower frequency f1 and upper frequency f2 (where fc = (f1 + f2)/2), then the fractional bandwidth (FBW) is given by EBW = (f2 - f1)/fc. The fractional

bandwidth is expressed as a percentage. The higher the percentage, the wider the bandwidth. In an embodiment, wideband antennas typically have a fractional bandwidth of 10% or more. Further, antennas with the FBW of greater than 20% are referred to as ultra-wideband antennas.
[041] In an embodiment, the optimized value for (i) the length and the shape of the dipole antenna (102) in the far field, and (ii) the predetermined distanced between the dipole antenna (102) and the high impedance surface are obtained based on optimization of impedance bandwidth and circular polarization bandwidth. Here, the impedance bandwidth refers to a frequency range over which the dipole antenna’s return loss is <= -10dB and the circular polarization bandwidth refers to a frequency range over which a far-field radiation pattern displays Axial Ratio as <= 3dB. Best performance may be assessed empirically and accordingly the predetermined distance may be determined. In an embodiment, the optimized predetermined distance is 2 millimeter (mm).
[042] The wide band linear to circular polarization conversion can be better understood by way of the following description provided as exemplary explanation. when the dipole antenna 102 is excited, it radiates in both +/- Z-direction and a wave propagating in -Z direction impinges on the HIS and gets reflected. The S-shaped printed patches (which constitute HIS) display a functional property of linear-to-linear polarization conversion for the reflected wave from the high impedance surface. This means, if electric field of incoming wave is directed along +/- X direction, after reflection from a surface, major part of the wave’s electric field goes along +/- Y direction. Now, the reflected wave interferes with direct radiated wave from the dipole antenna 102 (i.e., in +Z direction), resulting in net far-field pattern. In an embodiment, circular polarization can be obtained by generating two orthogonal beams equal in amplitude and separated by 90 deg in phase. It is observed that the reflected wave displays strong cross-polarized component (i.e., E-field along +/- Y direction). On the other hand, direct wave is co-polarized (i.e. +/- X direction). Thus, overall structure of the flat antenna reflect array system is optimized so that conditions for circular polarization are met in far-field. It may be noted that the circular polarization is achieved when height of the

dipole antenna above the HIS is optimized and the optimized height is 2mm in the system of present disclosure.
[043] When the height is increased to 6mm or more, dual linearly polarized wave is obtained which does not match the requirement of obtaining circularly polarized wave. In addition, if the height of dipole antenna is moved further up to 11mm, the beam shape distorts. Thus, the design as shown in FIG. 4A and FIG. 4B has optimum configuration for wide bandwidth circularly polarized antenna. It is to be noted that the length and shape (L-bent) of dipole antenna is also heuristically optimized for best performance.
[044] In an embodiment, the one or more hardware processors 114C are further configured by instructions to determine a capacitance value through the surface mount capacitor (108E) that is used to shift operation frequency and tune bandwidth of the wide band linear to circular polarization conversion post-fabrication.
[045] FIG. 5 is an exemplary flow diagram illustrating a processor implemented method for wideband linear to circular polarization conversion of a flat antenna based reflect array system, in accordance with an embodiment of the present disclosure. The steps of the method 200 will now be explained in detail with reference to the components of the system 100 of FIG.1. Although process steps, method steps, techniques or the like may be described in a sequential order, such processes, methods and techniques may be configured to work in alternate orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. The steps of processes described herein may be performed in any order practical. Further, some steps may be performed simultaneously.
[046] In accordance with an embodiment of the present disclosure, the method 200 comprises, positioning, at step 202, the dipole antenna 102 on a first substrate 104 such that the dipole antenna 102 cooperates with a Radio Frequency (RF) input 106 of the system 100 to receive and transmit the radio waves. The high impedance surface 108 is disposed, at step 204, at a predetermined distance from the dipole antenna 102 and configured to reflect the radio waves such that a wide

band circularly polarized wave is obtained by conversion from linear to circular polarization, wherein the high impedance surface 108 is characterized by the second substrate 108A that accommodates the plurality of S-shaped printed patches 108B on the first surface and the conducting plate 108C on the opposite surface, wherein the conducting plate 108C is connected to a ground terminal and an air gap exists between the first substrate and the second substrate. Here, each of the plurality of S-shaped printed patches 108B and sides of the second substrate 108A are separated by a predefined region 108D. Further, each of the plurality of S-shaped printed patches 108B comprises two halves that are separated at a centre thereof by a surface mount capacitor 108E, and a plurality of posts 108F having a first end and a second end, positioned on opposite sides of the conducting plate 108C, wherein the first end is coupled to a portion of a part of the two halves of each of the plurality of S-shaped printed patch 108B and the second end is connected to the conducting plate 108C. At step 206, the pair of unbalanced transmission lines are transformed to a pair of balanced transmission lines 112 using the BALUN device 110. At step 208, the one or more hardware processors 114C are configured to obtain an optimized value for (i) length and shape of the dipole antenna 102 in far field and (ii) the predetermined distanced between the dipole antenna 102 and the high impedance surface 108 to achieve a wide band linear to circular polarization conversion. At step 210, the one or more hardware processors 114C are configured to determine a capacitance value through the surface mount capacitor 108E that is used to shift operation frequency and tune bandwidth of the wide band linear to circular polarization conversion post-fabrication.
[047] In an embodiment, the flat antenna based reflect array system 100 further comprises exhibiting functional modularity and providing an improved directivity upon being cascaded side by side.
[048] FIG. 6A illustrates frequency and circular polarization bandwidths plots of the flat antenna based reflect array system for different values of capacitors in terms of axial ratio and frequency. As seen in FIG. 6A, different capacitance values enable fine tuning of axial ratio bandwidth. Since the surface mount capacitors are assembled only after surface module is printed, this method enables

engineer to test and tune as per operational need thereby taking into consideration the fabrication tolerances. FIG. 6B illustrates frequency and circular polarization bandwidths plots of the flat antenna based reflect array system for different values of capacitors in terms of return loss and frequency. As shown in FIG. 6B, the return loss figures do not change significantly for capacitance range of 2pf to 10pf. It is observed from both FIG. 6A and FIG. 6B that different capacitance values shift the circular polarization bandwidth while retaining the impedance bandwidth. This indicates towards an ability to retune antenna vide appropriate choice of capacitance values.
[049] FIG.7 is a 2-Dimensional radiation pattern of the flat antenna based reflect array system 100 according to some embodiments of the present disclosure. Radiation gain of the flat antenna based reflect array system 100, has been depicted as a function of total realized gain in two orthogonal planes. The radiation pattern has been plotted for both φ equals 0° and 90° plane. The spherical coordinates are:
• Radius, r: vector length from origin to point of interest.
• Polar angle, θ: angle between the vector and positive z-axis.
• Azimuth, φ: angle between the vector's projection onto the x-y plane and the positive x-axis.
[050] In the radiation plot, the numerical values distributed over the outermost circle represents the angle θ and the numerical values (vertically arranged) mentioned at the circumference of each inner circle represent the total realized gain value in dB. It may be observed from FIG.7 that the two orthogonal beams are well formed still there exists an asymmetry in beam shape. This asymmetry is intelligently utilized in a similar way as in case of shaped-beam antennas. It is noted from FIG. 7 that the Gain of approximately 7.3 dBi is obtained using the system of the present disclosure. Normally, a standard half-wavelength dipole provides a gain of approximately 2dBi only. Further, dipole gain of 5.2dBi is obtained for L = 1.25λ. However, in the system of present disclosure, a higher gain of 7.3dBi along with wide band circular polarization is obtained using antenna dimension of 1.15λ X 1.15λX 0.22λ at centre frequency of 12.6GHz.

[051] FIG.8 illustrates an example of cascaded flat antenna based reflect array systems for increased gain and improved directivity, according to some embodiments of the present disclosure. In an embodiment, aim is to obtain an optimum gain which is a key requirement for multiple applications. This is achieved by cascading multiple flat antenna based reflect array systems side by side as shown in FIG. 8. Further, in typical VSAT earth stations, gain requirements may vary from 30dB to well above 40dB. Using the design proposed in the system of the present disclosure, if 10X10 systems (where 1 system is shown in FIG. 2A) are utilized, then a minimum gain of 32dBi can be obtained. Further, if 30X30 systems are utilized, then a minimum gain of 42dBi can be obtained. For 10X10 systems, total aperture size requirement is approximately 0.28mX0.28m whereas for 30X30, the total aperture size requirement size is 0.82mX0.82m. It may be notes that both size requirements are less than the currently available parabolic dish diameter for this frequency.
[052] The written description describes the subject matter herein to enable any person skilled in the art to make and use the embodiments. The scope of the subject matter embodiments is defined by the claims and may include other modifications that occur to those skilled in the art. Such other modifications are intended to be within the scope of the claims if they have similar elements that do not differ from the literal language of the claims or if they include equivalent elements with insubstantial differences from the literal language of the claims.
[053] It is to be understood that the scope of the protection is extended to such a program and in addition to a computer-readable means having a message therein; such computer-readable storage means contain program-code means for implementation of one or more steps of the method, when the program runs on a server or mobile device or any suitable programmable device. The hardware device can be any kind of device which can be programmed including e.g., any kind of computer like a server or a personal computer, or the like, or any combination thereof. The device may also include means which could be e.g., hardware means like e.g., an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination of hardware and software means, e.g., an ASIC

and an FPGA, or at least one microprocessor and at least one memory with software processing components located therein. Thus, the means can include both hardware means and software means. The method embodiments described herein could be implemented in hardware and software. The device may also include software means. Alternatively, the embodiments may be implemented on different hardware devices, e.g., using a plurality of CPUs.
[054] The embodiments herein can comprise hardware and software elements. The embodiments that are implemented in software include but are not limited to, firmware, resident software, microcode, etc. The functions performed by various components described herein may be implemented in other components or combinations of other components. For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can comprise, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.
[055] The illustrated steps are set out to explain the exemplary embodiments shown, and it should be anticipated that ongoing technological development will change the manner in which particular functions are performed. These examples are presented herein for purposes of illustration, and not limitation. Further, the boundaries of the functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternative boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. Alternatives (including equivalents, extensions, variations, deviations, etc., of those described herein) will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. Such alternatives fall within the scope of the disclosed embodiments. Also, the words “comprising,” “having,” “containing,” and “including,” and other similar forms are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

[056] Furthermore, one or more computer-readable storage media may be utilized in implementing embodiments consistent with the present disclosure. A computer-readable storage medium refers to any type of physical memory on which information or data readable by a processor may be stored. Thus, a computer-readable storage medium may store instructions for execution by one or more processors, including instructions for causing the processor(s) to perform steps or stages consistent with the embodiments described herein. The term “computer-readable medium” should be understood to include tangible items and exclude carrier waves and transient signals, i.e., be non-transitory. Examples include random access memory (RAM), read-only memory (ROM), volatile memory, nonvolatile memory, hard drives, CD ROMs, DVDs, flash drives, disks, and any other known physical storage media.
[057] It is intended that the disclosure and examples be considered as exemplary only, with a true scope of disclosed embodiments being indicated by the following claims.

We Claim:
1. A flat antenna based reflect array system (100), comprising:
a dipole antenna (102) positioned on a first substrate (104) and
cooperating with a Radio Frequency (RF) input (106) to receive and
transmit radio waves;
a high impedance surface (108) disposed at a predetermined distance
from the dipole antenna (102) and configured to reflect the radio waves such
that a wide band circularly polarized wave is obtained by conversion from
linear to circular polarization, wherein the high impedance surface (108) is
characterized by:
a second substrate (108A) that accommodates a plurality of S-shaped printed patches (108B) on a first surface and a conducting plate (108C) on an opposite surface, wherein the conducting plate (108C) is connected to a ground terminal and an air gap exists between the first substrate (104) and the second substrate (108A),
each of the plurality of S-shaped printed patches (108B) and sides of the second substrate (108A) are separated by a predefined region(108D),
each of the plurality of S-shaped printed patches (108B) comprises two halves that are separated at a centre thereof by a surface mount capacitor (108E), and
a plurality of posts (108F) having a first end and a second end, positioned on opposite sides of the conducting plate (108C), wherein the first end is coupled to a portion of a part of the two halves of each of the plurality of S-shaped printed patch (108B) and the second end is connected to the conducting plate (108C); a BALUN device (110) to transform a pair of unbalanced
transmission lines to a pair of balanced transmission lines (112); and
a controller unit (114) in communication with the BALUN device,
wherein the controller unit (114) comprises:

one or more data storage devices (114A) configured to store instructions;
one or more communication interfaces (114B); and one or more hardware processors (114C) operatively coupled to the one or more data storage devices via the one or more communication interfaces (114B), wherein the one or more hardware processors (114C) are configured by the instructions to:
obtain an optimized value for (i) length and shape of the dipole antenna (102), and (ii) the predetermined distanced between the dipole antenna in far field (102) and the high impedance surface (108) to achieve a wide band linear to circular polarization conversion; and
determine a capacitance value through the surface mount capacitor (108E) that is used to shift operation frequency and tune bandwidth of the wide band linear to circular polarization conversion post-fabrication.

2. The flat antenna based reflect array system of claim 1, wherein the dipole antenna (102) is characterized by:
two half-wavelength L-bent shaped conducting elements (102A) that are separated by a predefined distance and positioned on the first substrate (104) with each of the two half-wavelength L-bent shaped conducting elements (102A) having length along a X-axis and bent along a Y-axis in an XY plane of a Cartesian coordinate system;
a feeding point (102B) disposed in a portion of the bent along the Y-axis of each of the two L-bent shaped conducting elements (102A); and
the pair of balanced transmission lines (112) from the BALUN device (110) that are connected to the feeding point (102B) of each of the two L-bent shaped conducting elements (102A) by passing through the first substrate (104) and the second substrate (108A).

3. The flat antenna based reflect array system of claim 1, wherein the optimized value for (i) the length and the shape of the dipole antenna (102) in the far field, and (ii) the predetermined distanced between the dipole antenna (102) and the high impedance surface are obtained based on optimization of impedance bandwidth and circular polarization bandwidth.
4. The flat antenna based reflect array system of claim 1, wherein the optimized predetermined distance is 2 millimeter (mm).
5. The flat antenna based reflect array system of claim 1, further comprising exhibiting functional modularity and providing an improved directivity upon being cascaded side by side.
6. A processor implemented method (200) comprising the steps of:
positioning (202), a dipole antenna (102) on a first substrate (104) and cooperating with a Radio Frequency (RF) input (106) to receive and transmit radio waves;
disposing (204), a high impedance surface (108) at a predetermined distance from the dipole antenna (102) and configured to reflect the radio waves such that a wide band circularly polarized wave is obtained by conversion from linear to circular polarization, wherein the high impedance surface (108) is characterized by:
a second substrate (108A) that accommodates a plurality of S-shaped printed patches (108B) on a first surface and a conducting plate (108C) on an opposite surface, wherein the conducting plate (108C) is connected to a ground terminal and an air gap exists between the first substrate and the second substrate,
each of the plurality of S-shaped printed patches (108B) and sides of the second substrate (108A) are separated by a predefined region(108D),

each of the plurality of S-shaped printed patches (108B) comprises two halves that are separated at a centre thereof by a surface mount capacitor (108E), and
a plurality of posts (108F) having a first end and a second
end, positioned on opposite sides of the conducting plate (108C),
wherein the first end is coupled to a portion of a part of the two
halves of each of the plurality of S-shaped printed patch (108B) and
the second end is connected to the conducting plate (108C);
transforming (206), using a BALUN device (110), a pair of
unbalanced transmission lines to a pair of balanced transmission lines (112);
obtaining (208), via one or more hardware processors, an optimized
value for (i) length and shape of the dipole antenna (102) in far field and (ii)
the predetermined distanced between the dipole antenna (102) and the high
impedance surface (108) to achieve a wide band linear to circular
polarization conversion; and
determining (210), via the one or more hardware processors, a capacitance value through the surface mount capacitor (108E) that is used to shift operation frequency and tune bandwidth of the wide band linear to circular polarization conversion post-fabrication.

7. The processor implemented method of claim 6, wherein the dipole antenna (102) is characterized by:
two half-wavelength L-bent shaped conducting elements (102A) that are separated by a predefined distance and positioned on the first substrate (104) with each of the two half-wavelength L-bent shaped conducting elements (102A) having length along a X-axis and bent along a Y-axis in an XY plane of a Cartesian coordinate system;
a feeding point (102B) disposed in a portion of the bent along the Y-axis of each of the two L-bent shaped conducting elements (102A); and
the pair of balanced transmission lines (112) from the BALUN device (110) that are connected to the feeding point (102B) of each of the

two L-bent shaped conducting elements (102A) by passing through the first substrate (104) and the second substrate (108A).
8. The processor implemented method of claim 6, wherein the optimized value for (i) the length and the shape of the dipole antenna (102) in the far field, and (ii) the predetermined distanced between the dipole antenna (102) and the high impedance surface are obtained based on optimization of impedance bandwidth and circular polarization bandwidth.
9. The processor implemented method of claim 6, wherein the optimized predetermined distance is 2 millimeter (mm).
10. The processor implemented method of claim 6, further comprising exhibiting functional modularity and providing an improved directivity upon being cascaded side by side.