Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P1/00—Auxiliary devices
  • H01P1/20—Frequency-selective devices, e.g. filters
  • H01P1/2005—Electromagnetic photonic bandgaps [EPB], or photonic bandgaps [PBG]
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers
  • G03F7/091—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement
• • 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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/10—Resonant slot antennas
  • H01Q13/106—Microstrip slot antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
• • 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
  • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
  • H01Q9/26—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength
  • H01Q9/27—Spiral antennas

Definitions

• the present invention is related to planar broadband antennas and, more particularly, to an antenna for transmitting or receiving circularly-polarized signals.
• the directivity of a patch antenna can be increased by incorporation of a choke ring ground plane, but this increases the weight of the antenna.
• U.S. Patent No. 5,815,122 issued to Nurnberger et al., for example, discloses a slot spiral antenna with a single spiral slot on one side of the antenna, and a spiral microstrip feed line on the reverse side.
• the reference teaches primarily a single-slot configuration which results in an antenna having a low directivity.
• an additional component such as a low-noise amplifier, on the antenna itself is impractical.
• planar antennas producing circularly-polarized radiation there remains a need for improvements that offer advantages and capabilities not found in presently available devices, and it is a primary object of this invention to provide such improvements. It is another object of the invention to provide such a planar antenna with an improved directivity.
• a planar antenna includes a nonconductive substantially planar substrate and a transmission line disposed on one surface, a segment of the transmission line forming an arc of radius R centered on the antenna axis.
• a conductive layer on the other antenna surface includes two or more slotted openings, each slotted opening having one end located within a distance R of the antenna axis, such that, when an electromagnetic signal is fed into one end of the transmission line, electromagnetic energy is sequentially coupled into the slotted openings, and a circularly-polarized signal is radiated from the antenna substantially in the direction of the antenna axis.
• the electrical phase length of the transmission line is matched to the spatial angular difference between two consecutive slotted openings, so as to provide for a phased-array operation.
• Fig. 1 is a diagrammatical view of the back side of an antenna in accordance with the present invention showing an arc-shaped transmission line disposed about an antenna axis
• Fig. 2 is a cross-sectional view of the antenna of Fig. 1 showing a conductive plane disposed on the antenna front side;
• Fig. 3 is a diagrammatical view of the front side of the antenna of Fig. 1 showing an array of slotted openings disposed in the conductive plane;
• Fig. 4 is an end view of the antenna of Fig. 3 showing the placement of an optional reflector to increase the proportion of electromagnetic energy transmitted in the antenna forward direction;
• Fig. 5 is a first embodiment of an antenna including four equal-length slotted openings arrayed at 90° intervals about the antenna axis;
• Fig. 6 is a view of the back side of the antenna of Fig. 5 showing an signal amplifier and an impedance load attached to the ends of a transmission line;
• Fig. 7 is a second embodiment of an antenna including curved slotted openings with straight radial slotted segments to increase coupling between the slotted openings and a transmission line;
• Fig. 8 is a third embodiment of an antenna including clockwise spiral slotted openings of two different lengths for transmitting or receiving left-hand polarized signals of two different wavelengths;
• Fig. 10 is a front view of a fourth embodiment of an antenna with high directivity including twelve spiral-shaped slotted openings equally arrayed about the antenna axis;
• Fig. 11 is a front view of a fifth embodiment of an antenna including an array of straight slotted openings; and Fig. 12 is a rear view of the antenna of Fig. 1 1 showing low-noise signal amplifiers attached to the ends of a transmission line.
• Fig. 1 is a diagrammatical view showing the back side of a substantially planar antenna 10 for receiving or transmitting electromagnetic signals of wavelength ⁇ , in accordance with the present invention.
• a back surface 13 of the antenna 10 is bounded by a peripheral edge 17.
• the peripheral edge 17 encloses an antenna axis 11 oriented orthogonal to the back surface 13.
• the transmission line 21 includes an input end 23 for receiving or outputting the electromagnetic signals.
• the input end is electrically connected by a first conductive lead 12 to a connector 22, such as an RF connector, for interfacing with external circuitry.
• Fig. 2 is a cross-sectional view of the antenna 10 as indicated by the sectional arrows in Fig. 1.
• the antenna 10 comprises a substrate 19 of nonconductive or dielectric material having a thickness t , where the transmission line 21 is disposed on the back surface 13 of the substrate 19 and a conductive layer 31 is disposed on a front surface 15 of the substrate 19.
• the front surface 15 is likewise bounded by the peripheral edge 17.
• slotted openings are shown for purpose of illustration, the present invention is not limited to this number and may comprise m slotted openings of varying shapes and lengths, where m ⁇ 2 , as explained in greater detail below.
• the slotted openings can be curved in shape as shown, or can be straight segments or a combination of both straight and curved segments, as described in greater detail below.
• the curved shapes can be a conical section (i.e., a circular, elliptical, parabolic, or hyperbolic arc), an Archimedean spiral, a logarithmic spiral, or an exponential spiral.
• Straight slotted openings are equivalent to dipoles and, as such, a single slotted opening produces a linearly polarized signal.
• an array of straight slotted openings can be used to transmit, or receive, a circularly-polarized signal, as described in greater detail below.
• Circular polarization can also be produced by using an array of curved slotted openings, where the respective slotted openings are curved in the direction of the desired circular polarization (i.e., a clockwise curvature to receive or transmit left-hand circularly polarized signals).
• This electromagnetic energy will be similarly coupled into slotted openings 35, 37, and 39 at coupling regions 45, 47, and 49 respectively.
• the degree of coupling is a function of the thickness t of the substrate 19, the width w of the transmission line 21, the width v of the slotted opening 33, and the dielectric properties of the substrate 19.
• radiation energy is received at the slotted openings 33, 35, 37, and 39 is coupled into the transmission line 21 at the respective coupling regions 43, 45, 47, and 49.
• electromagnetic energy radiated by the antenna 10 is emitted in both directions along the antenna axis 11.
• a reflector 40 may be emplaced in opposed parallel relationship to the back surface 13 of the antenna 10, as shown in Fig. 4.
• an enclosed cavity (not shown) could be used in place of the reflector 40 as is well-known in the relevant art.
• the radiation pattern emitted from the antenna 10, as well as the radiation pattern roll-off characteristics, can also be varied as desired by increasing or decreasing the separation between the reflector 40 and the antenna 10.
• Fig. 5 is the front view of a first embodiment of a planar antenna 50 in accordance with the present invention.
• the planar antenna 50 includes four similar spiral-shaped slotted openings 53, 55, 57, and 59 each of width v and guided wave length L GW
• the radial distances r ⁇ ) of the interior edges of the slotted openings 53, 55, 57, and 59 increase from r a at the respective axial ends 53a, 55a, 57a, and 59a, to a maximum radius of r p at the respective peripheral ends 53p, 55p, 57p, and
• the radial distance from the antenna axis 51 to the inside edge of any of the slotted opening 53, 55, 57, and 59 increases with the polar angle ⁇ and is also a function of the interval spacing Ar for each spiral-shaped slotted opening where ⁇ r ⁇ r( ⁇ + 2 ⁇ ) - r( ⁇ ) .
• the slotted opening 55 is spatially offset from the slotted opening 53 by —
• each spiral-shaped slotted opening subtends an angle of ⁇ p ,
• each of the slotted openings 53, 55, 57, and 59 is specified to be substantially smaller than the guided wave length and large enough to enable good electromagnetic coupling between the respective slotted opening 53, 55, 57, and 59 and a transmission line 61, best seen in Fig. 6 which is a rear view of the planar antenna 50.
• the transmission line 61 "crosses" each of the slotted openings 53, 55, 57, and 59 at respective coupling regions 63, 65, 67, and 69.
• the coupling regions 63, 65, 67, and 69 7T are offset by — radians (90°) from one another.
• This configuration provides for matching the electrical phase differences in the coupling regions 63, 65, 67, and 69 (i.e., differences of 90°) with the spatial differences of the slotted openings 53, 55, 57, and 59 when the guided wave length of the transmission line 61 is tuned to be one wavelength ⁇ .
• a single, omnidirectional beam is produced when the guided wave length of the transmission line 61 is one wavelength ⁇
• a squinted beam is produced when the guided wave length is less than one wavelength
• multiple directional beams are produced when the guided wave length of the transmission line 61 is more than one wavelength.
• a transmitted signal originating in the low-noise amplifier 71 and terminating in the impedance load 73 passes through the transmission line 61 in a counter-clockwise direction (as viewed from the front of the planar antenna 50).
• the transmitted signal is successively coupled to the slotted openings 53, 55, 57, and 59 at the respective coupling regions 63, 65, 67, and 69, a right-hand polarized signal is emitted from the planar antenna 50.
• the signal can be transmitted through the transmission line 61 in a clockwise direction and the slotted openings 53, 55, 57, and 59 can be curved in a clockwise direction for a transmitted (or received) signal which is left-hand polarized.
• an antenna 80 comprises an array of four slotted openings 81, 83, 85, and 89 coupled to the transmission line 61 (on the back side of the antenna 80).
• the slotted openings 81, 83, 85, and 87 each include a straight, radial segment 89 oriented at a right angle to the transmission line 61.
• an antenna 90 is configured to transmit and receive left-hand polarized signals at two wavelengths, ⁇ ! and ⁇ 2 .
• Two slotted openings 91 and 95 are tuned for the longer wavelength ⁇ , , and two slotted openings 93 and 97 are tuned for the shorter wavelength ⁇ 2 .
• 91 can be tuned to the wavelength ⁇ , by having a guided wave length L GW of: i) one ⁇ wavelength ( ⁇ , ), ii) two wavelengths (2 ⁇ , ), iii) one-half wavelength (— - ),
• the antenna 90 comprises a transmission line 101 having a greater width in comparison to the width of transmission line 61 (in Fig. 6).
• a signal propagating within the transmission line 101 will appear mostly at the edges 103 and 105.
• the guided wave length along the inside edge 103 is smaller than the guided wave length D along the outside edge 105 by the fraction — .
• the transmission line 101 can be optimized for coupling more than one wavelength into the array of slotted openings 91, 93, 95, and 97.
• an antenna 110 comprises six slotted openings 111 tuned to a first wavelength ⁇ , and six slotted openings 113 tuned to a second, shorter wavelength ⁇ 2 .
• the array of slotted openings 111 are disposed about an antenna axis 115 within the array of slotted openings 113.
• the six slotted ⁇ openings 111 are spaced apart from one another at angular intervals of — radians (60°), and the six slotted openings 113 are spaced apart from one another at angular intervals of
• an antenna 120 comprises eight straight slotted openings 121a, 121b,..., and 121h arrayed about an antenna axis 123.
• Each slotted opening 121a— 121h is coupled to a transmission line 125 on the back side of the antenna 120, as shown in Fig. 12.
• a first end 127 of the transmission line 125 is connected to a first signal amplifier 131, and a second end 129 of the transmission line 125 is connected to a second signal amplifier 133.
• the second signal amplifier 133 can be replaced by a receiver (not shown), and the antenna 120 can be used to transmit left-handed circularly polarized signals via first signal amplifier 121 and to receive right-handed circularly polarized signals via the receiver.
• the first signal amplifier is also replaced by a second receiver (not shown), both left-hand polarized and right-hand polarized signals can be received by the antenna 120.

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• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Optics & Photonics (AREA)
• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Structural Engineering (AREA)
• General Physics & Mathematics (AREA)
• Waveguide Aerials (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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ID=23480406

Family Applications (1)

Country Status (6)

Cited By (8)

Families Citing this family (81)

Citations (2)

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• 1999
  • 1999-08-16 US US09/375,319 patent/US6445354B1/en not_active Expired - Lifetime
• 2000
  • 2000-07-26 EP EP00944164A patent/EP1205009B1/en not_active Expired - Lifetime
  • 2000-07-26 AU AU58396/00A patent/AU762854B2/en not_active Expired
  • 2000-07-26 JP JP2001517463A patent/JP4700873B2/ja not_active Expired - Lifetime
  • 2000-07-26 WO PCT/IB2000/001030 patent/WO2001013465A1/en not_active Ceased
  • 2000-07-26 DE DE60006132T patent/DE60006132T2/de not_active Expired - Lifetime
  • 2000-12-08 US US09/732,849 patent/US6452560B2/en not_active Expired - Lifetime

Patent Citations (2)

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