Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
  • H01Q19/005—Patch antenna using one or more coplanar parasitic elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/36—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith
  • H01Q1/38—Structural form of radiating elements, e.g. cone, spiral, umbrella; Particular materials used therewith formed by a conductive layer on an insulating support
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
  • H01Q9/0421—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with a shorting wall or a shorting pin at one end of the element
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
  • H01Q9/0428—Substantially flat resonant element parallel to ground plane, e.g. patch antenna radiating a circular polarised wave

Definitions

• Embodiments of the present invention relate to a circularly polarized antenna and more particularly to a circularly polarized microstrip patch antenna which is developed to mount on Low Earth Orbit (LEO) small satellites and capable of operating in the S band transmission application. Also, the circularly polarized microstrip patch antenna is easy to integrate with metallic and nonmetallic surfaces of any shape.
• LEO Low Earth Orbit
• Satellite communication is one of the most important modes of wireless communication and have significant role in the field of global telecommunications. There are approximately 2000 artificial satellites orbiting Earth and enable communication to and from multiple locations across the globe.
• a satellite has three main components namely communications system, power system and propulsion system.
• the communications system includes antennas and transponders enabling transfer of voice, video and data.
• the power system comprises of solar panels providing requisite power to drive the hardware of the satellite and other ancillary parts.
• the propulsion system having rockets which drive the satellite in a desired orientation in the space.
• the satellite communication technologies have been evolved rapidly in relatively short span of time.
• Today, the satellite communication technologies are very sophisticated and powerful.
• there is no dearth in demand for more refined technologies which are able to handle the ever increasing voice, video and data traffic. Therefore, there is a need of advanced satellites which can withstand such ever increasing demands of wireless communication.
• One of the advanced satellite technologies is 'small satellites' which enables accomplishing number of tasks and experiments in space.
• Small satellites came into existence because of the evolved miniaturized technologies. Besides the advantages of small satellite it is a challenge to provide all necessary components within the physical limitations and restrictions.
• One of the main concerns for small satellite is to have adequate, efficient and economical antenna.
• helical antennas were used in traditional satellite communication systems however they become unfit for small satellite.
• the small satellite antennas must have lightweight structure and high degree of integration. Further, the antennas are mostly provided on outer walls of the small satellite and are attached with a thermal blanket. Varied types of small antennas, low profile antennas or microstrip antennas have been developed to address critical requirements such as improved circular polarization, improved low angle radiation pattern, widen beams, enhanced gain at low angle , dual band operation etc.
• Such antenna have been developed by using slotted radiating patch, high dielectric material substrate, artificial magnetic conductor, electromagnetic band-gap (EBG) structure, metamaterial, and magnetodielectric materials etc.
• ESG electromagnetic band-gap
• Circularly polarized antennas have been developed by the researchers to be used in small satellite communication systems. Such types of antenna have a wide beam width and suitable to be used as global positioning system (GPS) receiving antennas, wireless local area network (LAN) antennas for ceiling installations, radio frequency identification (RFID) reader antennas for special use, and so forth.
• GPS global positioning system
• LAN wireless local area network
• RFID radio frequency identification
• circularly polarized patch antennas are appropriate for satellite communication in order to achieve satisfactory received power and orientation independence of the base station antenna.
• the structure of a patch antenna is frequently used.
• a patch antenna having a half wavelength size has a narrow beam width of about 70 degrees.
• the size of the patch is reduced so as to be still smaller than the half wavelength using a high-k substrate, or a ground plane having a three-dimensional structure such as a pyramid is used.
• a ground plane having a three-dimensional structure such as a pyramid is used.
• the return loss bandwidth of the antenna is reduced.
• the ground plane having a three-dimensional structure is used, the thickness of the antenna is increased.
• US 20120162021A1 talks about a circularly polarized antenna with a wide beam width, in which four U-shaped metal strips are disposed in a circular shape, and four signals having the same magnitude and phase difference intervals of 90 degrees are fed to the respective metal strips so as to transceive circularly polarized waves.
• the disclosed circularly polarized antenna includes a ground plane, a central patch formed in the center of an upper surface of the ground plane, and a plurality of radiation patches disposed above the ground plane and around the central patch in a circular shape, wherein signals having the same magnitude and preset phase differences are fed to respective radiation patches.
• US 6181281 B1 discloses another type of circularly polarized patch antenna which facilitates optimization of the axial ratio adjustment and impedance matching, and has an improved degree of freedom to optimize the axial ratio adjustment and the impedance matching.
• This antenna is comprised of a dielectric substrate, an approximately rectangular patch serving as a radiating element, a ground conductor serving as a ground plane formed on the substrate to be opposite to the patch and a feedpoint located on the patch for feeding or deriving electric power to or from the patch.
• Embodiments of the present invention aim to provide a circularly polarized microstrip patch antenna which has a low profile that adheres to the strictest nano-satellite launch policies.
• the proposed antenna utilizes unique asymmetric slits to achieve high gain circular polarization. Further, the asymmetric slits are employed to obtain circularly polarized radiation with a reduction in design size and complexity.
• the disclosed antenna can be mounted on any metallic or non-metallic surface without any effect on performance and the geometric parameters of the same can be adjusted to tune the return loss and bandwidth over S band frequency using the Ramped Convergence Particle Swarm Optimization (RCPSO) algorithm.
• RCPSO Ramped Convergence Particle Swarm Optimization
• the circularly polarized microstrip patch antenna comprising a substrate having a top surface and a bottom surface, four asymmetric slits, a passive thin strip and a ground plane.
• the four asymmetric slits and the passive thin strip are disposed on the top surface to form a patch and the patch is in electrical connection with the ground plane.
• the substrate having a hole for enabling the electrical connection between the patch and the ground plane.
• the ground plane is coupled with the bottom surface of the substrate.
• the substrate is a, but not limited to, microwave dielectric substrate. Further, the substrate is having a thickness of 1.57 mm.
• the substrate is having a dielectric constant of 2.2 and a dielectric loss tangent of 0.0009.
• the four asymmetric slits are having, but not limited to, a V shape.
• the passive thin strip is having, but not limited to, a rectangular shape.
• the ground plane is coupled with the bottom surface of the substrate by means of, but not limited to, a surface mount technique. While the present invention is described herein by way of example using embodiments and illustrative drawings, those skilled in the art will recognize that the invention is not limited to the embodiments of drawing or drawings described, and are not intended to represent the scale of the various components. Further, some components that may form a part of the invention may not be illustrated in certain figures, for ease of illustration, and such omissions do not limit the embodiments outlined in any way.
• compositions or an element or a group of elements are preceded with the transitional phrase "comprising”, it is understood that we also contemplate the same composition, element or group of elements with transitional phrases “consisting of, “consisting”, “selected from the group of consisting of, “including”, or “is” preceding the recitation of the composition, element or group of elements and vice versa.
• Fig. 1 illustrates a perspective view of a circularly polarized microstrip patch antenna in accordance with an embodiment of the present invention.
• Fig. 2 illustrates a patch of the circularly polarized microstrip patch antenna in accordance with an embodiment of the present invention.
• Fig. 3 illustrates a Smith chart of an experimental result in accordance with an embodiment of the present invention.
• Fig. 4 illustrates an antenna axial ratio diagram of an experimental result in operation bandwidth in accordance with an embodiment of the present invention.
• the present invention is described hereinafter by various embodiments with reference to the accompanying drawing, wherein reference numerals used in the accompanying drawing correspond to the like elements throughout the description.
• This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.
• numeric values and ranges are provided for various aspects of the implementations described. These values and ranges are to be treated as examples only, and are not intended to limit the scope of the claims.
• Embodiments of the present invention aim to provide a circularly polarized microstrip patch antenna which is capable of operating in the S band transmission application and can be easily mounted on LEO small satellites.
• the circularly polarized microstrip patch antenna has stable broadside radiation pattern with a high gain.
• the disclosed antenna utilizes robust microwave dielectric substrate that is resistant to harsh environment in outer space.
• the proposed antenna consists of coaxial probe fed asymmetric shaped patch with a passive rectangular strip.
• the disclosed antenna will be easy to integrate with metallic and nonmetallic surfaces of any shape.
• the circularly polarized microstrip patch antenna (100) as shown in figure 1 comprising a substrate (102), four asymmetric slits (104), a passive thin strip (106) and a ground plane (1 0).
• the substrate (102) is a, but not limited to, microwave dielectric substrate and is resistant to harsh environment in outer space.
• the substrate (102) is having a thickness of 1.57 mm, a dielectric constant of 2.2 and a dielectric loss tangent of 0.0009.
• the substrate (102) may be in a shape of, but not limited to, triangle, rectangle, circle, elliptical and may consists of glass microfiber reinforced Polytetrafluoroethylene (PTFE) composite material.
• the substrate (102) is having a top surface (102') and a bottom surface (102").
• the four asymmetric slits (104) are having a V shape and the passive thin strip (106) is having a rectangular shape.
• the four asymmetric slits (104) and the passive thin strip (106) are disposed on the top surface (102') of the substrate (102) to form a patch (108).
• a top view of the patch (108) of the circularly polarized microstrip patch antenna (100) is shown in figure 2 having a rectangular shape.
• the four asymmetric slits (104) enables to achieve circularly polarized radiation.
• the geometric parameters of the patch (108) can be adjusted to tune the return loss and bandwidth over S band frequency using the RCPSO algorithm.
• the RCPSO algorithm breaks down the optimization problem by considering only a subset of dimensions at a time and enable efficient gain optimization in antenna.
• the electric connection of the patch (108) with the ground plane (110) is enabled through a hole (1 2) in the substrate (102).
• the ground plane (110) is disposed on the bottom surface (102") of the substrate (102). Further, the ground plane (110) is completely covered in copper and contain no slots to achieve the high front to back radiation ratio.
• the patch (108) is in electrical connection with the ground plane (110) through a hole (112) in the substrate (102).
• the circularly polarized microstrip patch antenna (100) comprises of a signal-fed component (not shown) and a system ground unit (not shown).
• the signal-fed component provides electrical signal to the bottom surface (102") of the substrate (102) which in-turn generates an electromagnetic signal in conjunction with the ground plane (110).
• the electromagnetic signal is then passed on to the patch (108) where it is circularly polarized by means of the four asymmetric slits (104) and radiated accordingly.
• the signal-fed component may be a coaxial line, a coplanar line, or a SMA joint.
• the system ground unit may be connected to the substrate by Surface Mount Technique (SMT), wherein the system ground unit may be a conductive metal structure in the shape of a rectangle, possibly a metal structure in a shape of a circle, ellipse, triangle, rectangle, or polygon.
• SMT Surface Mount Technique
• Figure 3 illustrates a Smith chart (200) of an experimental result in accordance with an embodiment of the present invention showing that impedance bandwidth (VSWR ⁇ 2) of the proposed antenna is 60 MHz (2.24GHz-2.30 GHz).
• Figure 4 illustrates an antenna axial ratio diagram (300) of an experimental result in operation bandwidth in accordance with an embodiment of the present invention showing that circularly polarized benefit in axial ratio bandwidth of 3-dB is 0.74% (2.278-2.295 GHz) in the operating band.
• the above-mentioned circularly polarized microstrip patch antenna overcomes the problems and shortcomings of the existing circularly polarized antennas and also provides numerous advantages over them.
• the four asymmetric slits enables to achieve high gain circular polarization.
• the four asymmetric slits are utilized to obtain circularly polarized radiation with a reduction in size and complexity of the whole antenna.
• the asymmetric V-shaped slit and the rectangular shape of the patch provides a wide radiation beamwidth with significantly high gain.
• the disclosed antenna is capable of operating in the S band transmission application and easily mounted on LEO small satellites.
• the proposed antenna is easy to integrate with metallic and nonmetallic surfaces of any shape.
• the exemplary implementation described above is illustrated with specific shapes, dimensions, and other characteristics, but the scope of the invention also includes various other shapes, dimensions, and characteristics. For example, particular shape, size and attachment of the asymmetric slits, the thin strip, the substrate, and the ground plane. Also, the various attachments and the arrangement of the components such as substrate, ground plane, patch etc.
• the components as described in the present invention could be manufactured in various other ways and could include various other materials. Various modifications to these embodiments are apparent to those skilled in the art from the description and the accompanying drawings. The principles associated with the various embodiments described herein may be applied to other embodiments.

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Cited By (4)

Citations (1)

• 2015
  • 2015-03-12 MY MYPI2015700783A patent/MY162698A/en unknown
• 2016
  • 2016-03-11 WO PCT/MY2016/000011 patent/WO2016144155A1/en not_active Ceased

Patent Citations (1)

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