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EP3358675A1 - Antenne - Google Patents

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Publication number
EP3358675A1
EP3358675A1 EP17159144.9A EP17159144A EP3358675A1 EP 3358675 A1 EP3358675 A1 EP 3358675A1 EP 17159144 A EP17159144 A EP 17159144A EP 3358675 A1 EP3358675 A1 EP 3358675A1
Authority
EP
European Patent Office
Prior art keywords
antenna
parasitic element
parasitic
electric conductor
region
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP17159144.9A
Other languages
German (de)
English (en)
Inventor
Yuichiro Yamaguchi
Yoshihiro NIIHARA
Ning Guan
Hiroiku Tayama
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujikura Ltd
Original Assignee
Fujikura Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujikura Ltd filed Critical Fujikura Ltd
Publication of EP3358675A1 publication Critical patent/EP3358675A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/32—Adaptation for use in or on road or rail vehicles
    • H01Q1/325—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle
    • H01Q1/3283—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle side-mounted antennas, e.g. bumper-mounted, door-mounted
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/27—Adaptation for use in or on movable bodies
    • H01Q1/32—Adaptation for use in or on road or rail vehicles
    • H01Q1/325—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle
    • H01Q1/3275—Adaptation for use in or on road or rail vehicles characterised by the location of the antenna on the vehicle mounted on a horizontal surface of the vehicle, e.g. on roof, hood, trunk
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/30—Arrangements for providing operation on different wavebands
    • H01Q5/378—Combination of fed elements with parasitic elements
    • H01Q5/385—Two or more parasitic elements
    • 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
    • H01Q9/06—Details
    • H01Q9/065—Microstrip dipole antennas
    • 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
    • H01Q9/28—Conical, cylindrical, cage, strip, gauze, or like elements having an extended radiating surface; Elements comprising two conical surfaces having collinear axes and adjacent apices and fed by two-conductor transmission lines
    • H01Q9/285—Planar dipole
    • 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
    • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
    • H01Q9/40—Element having extended radiating surface
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems

Definitions

  • the present invention relates to an antenna.
  • automobiles have been provided with, in addition to conventionally used antennas which operate in frequency bands for FM/AM broadcasting, digital terrestrial broadcasting, and the like, antennas which operate in higher frequency bands, for example, frequency bands for 3G (3rd Generation: third generation mobile phones), LTE (Long Term Evolution), and the like.
  • 3G Third Generation: third generation mobile phones
  • LTE Long Term Evolution
  • Patent Literature 1 discloses an on-vehicle antenna device which includes a spoiler as a housing.
  • the on-vehicle antenna device is configured such that an antenna for LTE is provided in the spoiler which is mounted at a rear end of a roof of an automotive body.
  • Patent Literature 1 discloses, in Fig. 4 , an on-vehicle antenna device which is arranged so that an element constituting an antenna overlaps a metallic member constituting a rear end part of a roof. By causing the element to overlap the metallic member constituting the rear end part of the roof, it is possible to increase radiant gain in a direction across the roof (frontal direction of an automotive body).
  • an area of a region of an element which region overlaps the roof may change, and such a change may cause a change in input impedance of the antenna, depending on a type of an automobile.
  • the present invention has been made in view of the above problem, and an object of the present invention is to provide an antenna which is used in a state where the antenna is arranged so as to be adjacent to an electric conductor plate and which has desired input impedance independent of an area of a region of an element which region overlaps the electric conductor plate.
  • an antenna in accordance with an aspect of the present invention is an antenna including: a first element; a second element; a first parasitic element which surrounds, on three sides, one of ends of the first element which one is farther from a feed region; and a second parasitic element and a third parasitic element between which a middle part of the first element is sandwiched, each of the second parasitic element and the third parasitic element being galvanically insulated from the first parasitic element.
  • the antenna a given capacitance is formed between the first parasitic element and the one of the ends of the first element, which one is farther from the feed region. Therefore, in a case where the antenna is arranged so that the one of the ends of the first element overlaps an electric conductor plate (for example, an electric conductor plate constituting a roof which is part of an automotive body of an automobile), it is possible to suppress a change in capacitance between the first element and the electric conductor plate even in a case where an area of a region of the first element which region overlaps the electric conductor plate (hereinafter, referred to as an overlapping region) changes. As a result, according to the antenna, it is possible to suppress dependency of input impedance on the area of the overlapping region.
  • an electric conductor plate for example, an electric conductor plate constituting a roof which is part of an automotive body of an automobile
  • the second parasitic element and the third parasitic element it is possible to suppress reflection caused by mismatch between (i) impedance between the middle part and the second and third parasitic elements and (ii) impedance of a coaxial cable.
  • the antenna is capable of having desired input impedance, regardless of how large or small the area of the overlapping region is. It is therefore possible to provide an antenna which is used in a state where the antenna is arranged so as to be adjacent to an electric conductor plate and which has desired input impedance independent of an area of a region of an element which region overlaps the electric conductor plate.
  • an antenna which is used in a state where the antenna is arranged so as to be adjacent to an electric conductor plate and which has desired input impedance independent of an area of a region of an element which region overlaps the electric conductor plate.
  • the antenna 10 is an antenna which covers a frequency band for LTE (Long-Term Evolution) and which has a plurality of resonance points.
  • LTE Long-Term Evolution
  • Fig. 1 is a plan view illustrating a configuration of the antenna 10.
  • (a) of Fig. 2 is an enlarged view of a region R1 (see Fig. 1 ) of the antenna 10.
  • (b) of Fig. 2 is an enlarged view of a region R2 (see Fig. 1 ) of the antenna 10.
  • Fig. 3 is an exploded perspective view illustrating a state where the antenna 10 is arranged in a vicinity of an electric conductor plate 50.
  • (a) of Fig. 4 is a plan view of the antenna 10 in the state illustrated in Fig. 3 .
  • (b) of Fig. 4 is a right side view of the antenna 10 in the state illustrated in Fig. 3 .
  • the antenna 10 includes a substrate 11, an element 12, an element 13, a parasitic element 14, and a parasitic element pair 15.
  • the parasitic element pair 15 is made up of a parasitic element 15a and a parasitic element 15b.
  • the element 12, the element 13, the parasitic element 14, the parasitic element 15a, and the parasitic element 15b correspond to a first element, a second element, a first parasitic element, a second parasitic element, and a third parasitic element, respectively, recited in the claims.
  • the substrate 11 is constituted by a flexible film dielectric material. Since the substrate 11 is flexible, it is possible to wind the antenna 10 around a support 30 as later described with reference to Figs. 3 and 4 .
  • a polyimide resin is employed in the present embodiment. Note, however, that a polyimide resin is merely one of examples of a dielectric material. Therefore, the material is not limited to a polyimide resin.
  • the substrate 11 has a rectangular shape. Note that, in the present embodiment, a direction parallel to a long side of the substrate 11 will be referred to as a longitudinal direction, and a direction parallel to a short side of the substrate 11 will be referred to as a width direction.
  • the elements 12 and 13 and the parasitic elements 14, 15a, and 15b are each constituted by a thin plate member made of an electrically conductive foil (copper foil in the present embodiment), and are provided on one of surfaces of the substrate 11 by patterning.
  • Each of the elements 12 and 13 is fed with electric power through a feed cable (for example, a coaxial cable 20 illustrated in Fig. 3 ).
  • the antenna 10 can be referred to as a film antenna and can be also referred to as a FPC (Flexible printed circuits) substrate.
  • the element 12 has a tip part 12a, a middle part 12b, a root part 12c, a connection part 12d, and a connection part 12e.
  • the element 12 extends along the longitudinal direction of the substrate 11 so as to substantially have a belt shape.
  • the root part 12c constitutes one of ends of the element 12 (which one is closer to a straight line A-A illustrated in Fig. 1 )
  • the tip part 12a constitutes the other one of the ends of the element 12 (which other one is farther from the straight line A-A).
  • Part of the element 12 which part is surrounded by a body 14a of the parasitic element 14 is the tip part 12a
  • part of the element 12 which part is sandwiched by the parasitic element pair 15 is the middle part 12b.
  • the root part 12c has a width greater than those of the tip part 12a and the middle part 12b.
  • the root part 12c When viewed along the longitudinal direction of the substrate 11, the root part 12c is arranged on a middle part of the substrate 11.
  • the width of the root part 12c is (i) at one of ends of the root part 12c, substantially equal to a length of the short side of the substrate 11 and (ii) at the other one of the ends of the root part 12c, narrower than at the one of the ends of the root part 12c.
  • the width of the root part 12c gradually becomes narrower as the root part 12c extends from the one of the ends of the root part 12c toward the other one of the ends of the root part 12c.
  • the root part 12c has a cup shape (glass shape). Note that the root part 12c has, in the middle of the one of the ends of the root part 12c, a notch having a rectangular shape.
  • a belt shaped member extends, from the other one of the ends of the root part 12c, along a direction which is the longitudinal direction and which is a direction away from the straight line A-A.
  • the belt shaped member of the element 12 is made up of the connection part 12e, the middle part 12b, the connection part 12d, and the tip part 12a which are arranged in this order from the root part 12c. Note that a straight line C-C illustrated in Fig. 1 is indicative of a boundary between the connection part 12d and the tip part 12a.
  • the width of the root part 12c of the element 12 is, as described above, greater than that of the other part (the connection part 12e, the middle part 12b, the connection part 12d, and the tip part 12a) of the element 12. Note that a gap W3 between the root part 12c and the parasitic element 15a and a gap W4 between the root part 12c and the parasitic element 15b (see (b) of Fig. 2 ) will be later described in a section of the parasitic element pair 15.
  • connection part 12d Since the connection part 12d is inserted between the tip part 12a and the middle part 12b, it is possible to prevent the parasitic element 14 (later described) and the parasitic element pair 15 (later described) from being short-circuited. Furthermore, since the connection part 12e is inserted between the middle part 12b and the root part 12c, it is possible to prevent the root part 12c and the parasitic element pair 15 (later described) from being short-circuited. Note that a shape of the connection part 12d and a shape of the connection part 12e (in particular, the shape of the connection part 12d) are each not limited to a shape illustrated in Fig. 1 .
  • the element 13 has a root part 13a, a middle part 13b, and a tip part 13c.
  • the root part 13a has a rectangular shape, and is arranged along the notch of the root part 12c.
  • a belt shaped electric conductor extends, from one of ends of the root part 13a (which one is closer to the straight line A-A), along a direction which is the longitudinal direction and which is, out of directions away from the straight line A-A, a direction opposite to a direction in which the belt shaped member of the element 12 extends. Therefore, the straight line A-A illustrated in Fig. 1 is indicative of a main boundary between the element 12 and the element 13.
  • the belt shaped electric conductor of the element 13 is made up of the middle part 13b and the tip part 13c which are arranged in this order from the root part 13a.
  • the tip part 13c has a width which is uniform and which is substantially equal to the length of the short side of the substrate 11. Therefore, the width of the tip part 13c is greater than that of the root part 13a.
  • a straight line B-B illustrated in Fig. 1 is indicative of a boundary between the middle part 13b and the tip part 13c.
  • the middle part 13b has a width which (1) is, at the boundary between the middle part 13b and the tip part 13c (at the straight line B-B), equal to that of the tip part 13c, (2) is, at a boundary between the middle part 13b and the root part 13a (at the straight line A-A), equal to that of the root part 13a, and (3) gradually becomes narrower as the middle part 13b extends from the boundary between the middle part 13b and the tip part 13c toward the boundary between the middle part 13b and the root part 13a.
  • the middle part 13b has a cup shape (glass shape).
  • the antenna 10 is designed on the assumption that (i) one of electric conductors, of which the feed cable is made up, is connected to the root part 12c of the element 12 and (ii) the other one of the electric conductors, of which the feed cable is made up, is connected to the root part 13a of the element 13.
  • a region including (i) a region of the root part 12c to which region the one of the electric conductors is connected and which region is in a vicinity of the notch of the root part 12c and (ii) the root part 13a to which the other one of the electric conductors is connected, will be referred to as a feed region Rf.
  • the feed region Rf is located in a vicinity of the straight line A-A and on a side of the straight line A-A on which side the belt shaped member of the element 12 extends.
  • the root part 12c constitutes one of the ends of the element 12 which one is closer to the feed region Rf
  • the tip part 12a constitutes the other one of the ends of the element 12 which other one is farther from the feed region Rf.
  • the root part 13a constitutes one of ends of the element 13 which one is closer to the feed region Rf
  • the tip part 13c constitutes the other one of the ends of the element 13 which other one is farther from the feed region Rf.
  • the parasitic element 14 has a body 14a, a sub element 14b, and a sub element 14c.
  • the sub element 14b and the sub element 14c correspond to a first extending part and a second extending part, respectively, recited in the claims.
  • the body 14a is arranged so as to be adjacent to the tip part 12a of the element 12 and so as to surround the tip part 12a on three sides.
  • the body 14a substantially has a rectangular shape, and has a width substantially equal to that of the substrate 11.
  • a notch which has a rectangular shape and which corresponds to a shape of the tip part 12a is provided.
  • a position of the one of the sides of the body 14a matches that of the straight line C-C.
  • the tip part 12a is arranged in the notch thus provided of the body 14a so as to be adjacent to the body 14a.
  • the parasitic element 14 thus arranged is set so that a gap W1 between the body 14a and the tip part 12a (see (a) of Fig. 2 ) is uniform on three sides on which the body 14a surrounds the tip part 12a.
  • the width of the tip part 12a and the gap W1 are set, as appropriate, so that impedance between the tip part 12a and the body 14a has a value suitable for a virtual feed point.
  • the parasitic element 14 having the body 14a Since the parasitic element 14 having the body 14a is provided, a given capacitance is formed between the tip part 12a and the body 14a of the parasitic element 14. Therefore, in a case where the antenna 10 is arranged so that the tip part 12a overlaps an electric conductor plate (for example, an electric conductor plate constituting a roof which is part of an automotive body of an automobile), it is possible to suppress a change in capacitance between the element 12 and the electric conductor plate even in a case where an area of a region of the tip part 12a of the element 12 which region overlaps the electric conductor plate (hereinafter, referred to as an overlapping region) changes. As a result, according to the antenna 10, it is possible to suppress dependency of input impedance on the area of the overlapping region.
  • an electric conductor plate for example, an electric conductor plate constituting a roof which is part of an automotive body of an automobile
  • the sub element 14b and the sub element 14c extend, from respective parts of the one of the sides of the body 14a in which parts the notch is not provided, along a direction which is the longitudinal direction and which is a direction toward the straight line A-A.
  • the sub element 14b and the sub element 14c extend along respective outer sides of the parasitic element 15a and the parasitic element 15b (later described).
  • the body 14a Since the body 14a is arranged so as to be adjacent to the tip part 12a, electromagnetic coupling is formed between the tip part 12a and the body 14a. As a result, a boundary region between the tip part 12a and the body 14a functions as a virtual feed point.
  • the parasitic element 14 functions as a kind of element, although the parasitic element 14 is a parasitic element galvanically insulated from the element 12.
  • a length of the sub element 14b which length is measured from the straight line C-C along the longitudinal direction will be referred to as an element length of the sub element 14b.
  • a length of sub element 14c which length is measured from the straight line C-C along the longitudinal direction will be referred to as an element length of the sub element 14c.
  • the element length of the sub element 14b is set so as to be longer than that of the sub element 14c. Therefore, a virtual electrical length of the sub element 14b is longer than that of the sub element 14c.
  • the parasitic element pair 15 is made up of the parasitic element 15a and the parasitic element 15b.
  • the parasitic element 15a and the parasitic element 15b are arranged so that the middle part 12b of the element 12 is sandwiched between the parasitic element 15a and the parasitic element 15b and so that the parasitic element 15a and the parasitic element 15b are adjacent to respective both sides of the middle part 12b (which both sides faces each other in a state where the width direction is a normal direction).
  • the parasitic element 15a is galvanically insulated from each of the parasitic element 14 and the element 12.
  • the parasitic element 15b is galvanically insulated from each of the parasitic element 14 and the element 12.
  • the parasitic element 15a substantially has a trapezoidal shape, although a leg 15a1 which is one of legs of such a trapezoid is curved. That is, two sides extending along a direction in which the middle part 12b extends (two sides constituting respective lower and upper bases of the trapezoid) are parallel to each other. Note that, in the present embodiment, the lower base and the upper base are each parallel to the direction in which the middle part 12b extends.
  • the parasitic element 15a and the parasitic element 15b are symmetrical with respect to a center line, serving as a symmetrical axis, of the middle part 12b (a line passing through a midpoint, in the width direction, of the middle part 12b). That is, the parasitic element 15b substantially has a trapezoidal shape, although a leg 15b1 is curved, as with the case of the parasitic element 15a.
  • a side of the parasitic element pair 15, made up of the parasitic element 15a and the parasitic element 15b, which side is closer to the middle part 12b will be referred to as an inner side
  • a side of the parasitic element pair 15 which side is farther from the middle part 12b will be referred to as an outer side. Therefore, the lower base of the parasitic element 15a constitutes an innermost part of a contour of the parasitic element 15a, and the upper base of the parasitic element 15a constitutes an outermost part of the contour of the parasitic element 15a.
  • the leg 15a1 constitutes part of an outer part of the contour of the parasitic element 15a.
  • an inner side and an outer side are similarly defined.
  • the parasitic element pair 15 thus arranged is set so that a gap W2 between the parasitic element 15a and the middle part 12b and a gap W2 between the parasitic element 15b and the middle part 12b (see (a) of Fig. 2 ) are uniform.
  • the width of the middle part 12b and the gaps W2 are set, as appropriate, so that impedance between the middle part 12b and the parasitic element pair 15 matches impedance of the feed cable.
  • the antenna 10 including the foregoing parasitic element 14 and the foregoing parasitic element pair 15 is capable of having desired input impedance, regardless of how large or small the area of the overlapping region is. It is therefore possible to provide an antenna which is used in a state where the antenna is arranged so as to be adjacent to an electric conductor plate and which has desired input impedance independent of an area of a region of an element which region overlaps the electric conductor plate.
  • the antenna 10 is preferably used while (i) the element 12 is being connected to a cold side electric conductor of the feed cable and (ii) the element 13 is being connected to a hot side electric conductor of the feed cable.
  • the antenna 10 it is possible to further suppress the dependency of the input impedance on the area of the overlapping region, as compared with a case where (i) the element 12 is connected to the hot side electric conductor of the feed cable and (ii) the element 13 is connected to the cold side electric conductor of the feed cable.
  • part of the element 12 (the root part 12c) which part is included in the feed region Rf is set as a cold side feed point Pc
  • part of the element 13 (the root part 13a) which part is included in the feed region Rf is set as a hot side feed point Ph.
  • the feed cable is connected to the antenna 10
  • the cold side electric conductor of the feed cable is connected to the feed point Pc
  • the hot side electric conductor of the feed cable is connected to the feed point Ph.
  • the feed cable can be connected to the feed points Pc and Ph with use of, for example, solder.
  • the width of the middle part 12b is greater than that of the tip part 12a.
  • the element 12 is designed so that (1) the impedance between the tip part 12a and the body 14a and (2) the impedance between the middle part 12b and the parasitic element pair 15 have respective suitable values. Therefore, a relationship between the width of the tip part 12a and the width of the middle part 12b is not limited in particular.
  • the root part 12c of the element 12 is part of the element 12 which part is most adjacent to the element 13. Since the width of the root part 12c, which is adjacent to the element 13, of the element 12 is greater than that of the other part (the tip part 12a, the middle part 12b, the connection part 12d, and the connection part 12e) of the element 12, the element 12 is capable of operating suitably as a cold side element.
  • the fact that the element 12 has the root part 12c allows an increase in resonance frequency of the antenna 10. Therefore, it is possible to expand an operation band of the antenna 10.
  • gaps W5 and W6 between the element 12 and the element 13 are each arranged so as to, along a width direction of the element 13, be narrower on a center side of the element 13 and wider on an outer side of the element 13.
  • the gap W3 between the parasitic element 15a and the root part 12c is arranged so as to, along a width direction of the root part 12c (direction along the straight line A-A), become wider as extending from a center side of the root part 12c toward an outer side of the root part 12c (see (b) of Fig. 2 ).
  • the gap W4 between the parasitic element 15b and the root part 12c is arranged so as to, along the width direction of the root part 12c, become wider as extending from the center side of the root part 12c toward the outer side of the root part 12c.
  • a capacitance formed between the element 12 and the parasitic element 15a can be adjusted with use of the gap W3.
  • a capacitance formed between the element 12 and the parasitic element 15b can be adjusted with use of the gap W4. Therefore, according to the antenna 10, it is possible to easily cause impedance of the element 12 to match the impedance of the feed cable. Therefore, according to the antenna 10, it is possible to suppress a return loss in the element 12.
  • the root part 12c is arranged such that a side of the root part 12c which side faces a leg 15a2 of the parasitic element 15a and a side of the root part 12c which side faces a leg 15b2 of the parasitic element 15b are each constituted by a quarter-ellipse. That is, the root part 12c has a cup shape. According to such arrangement, it is possible to cause each of the gaps W3 and W4 to be narrower on the center side of the root part 12c and wider on the outer side of the root part 12c without reducing an area of each of the parasitic elements 15a and 15b.
  • the sub element 14b and the sub element 14c extend along the respective outer sides of the parasitic element 15a and the parasitic element 15b. Since each of the parasitic element 15a and the parasitic element 15b substantially has a trapezoidal shape, it is possible to arrange each of the sub element 14b and the sub element 14c on an outer side of a corresponding one of the parasitic element 15a and the parasitic element 15b without excessively reducing an area of the corresponding one of the parasitic element 15a and the parasitic element 15b. Furthermore, since each of the leg 15a1 and the leg 15b1 is curved toward an inside of the substantial trapezoid, it is possible to set the element length of each of the sub element 14b and the sub element 14c to be longer.
  • the fact that the parasitic element 14 has the sub element 14b and the sub element 14c allows an increase in resonance frequency of the antenna 10. Therefore, it is possible to expand the operation band of the antenna 10.
  • the sub element 14b and the sub element 14c are preferably different from each other in element length. This allows the sub element 14b and the sub element 14c to be different from each other in virtual electrical length. Therefore, it is possible to further increase the resonance frequency of the antenna 10.
  • the antenna 10 is used in a state where the antenna 10 is mounted on an automotive body of an automobile.
  • a case where the antenna 10 is housed in a spoiler 116 mounted at a rear end of a roof 120 of an automotive body 101 is assumed (later described with reference to Fig. 5 ).
  • the antenna 10 is connected to the coaxial cable 20, which is an aspect of the feed cable, and is housed in the spoiler 116 in a state where the antenna 10 is wound around the support 30 illustrated in Fig. 3 . Note that illustration of the support 30 is omitted in Fig. 4 .
  • the electric conductor plate 50 illustrated in Figs. 3 and 4 is one that is modeled on a spoiler fixing section 121d of the roof 120 illustrated in (b) of Fig. 5 .
  • a frontal direction of the automotive body 101 corresponds to a plus direction of a y-axis in coordinate systems illustrated in Figs. 3 and 4 .
  • the support 30 substantially has a rectangular parallelepiped shape, and is surrounded by walls 31 through 36 on six sides.
  • the wall 31 and the wall 36 face each other, and are arranged along an xy plane in the coordinate system illustrated in Fig. 3 .
  • the wall 32 and the wall 35 face each other, and are arranged along a zx plane in the coordinate system illustrated in Fig. 3 .
  • the wall 33 and the wall 34 face each other, and are arranged along a yz plane in the coordinate system illustrated in Fig. 3 .
  • the wall 31 is an upper wall
  • the wall 32 is a rear side wall
  • the wall 33 is a right side wall
  • the wall 34 is a left side wall
  • the wall 35 is a front side wall
  • the wall 36 is a lower wall, in a state where the walls 31 through 36 are illustrated in Fig. 3 .
  • the antenna 10 is wound around the support 30 so that (1) the tip part 13c is in contact with the wall 36, (2) the middle part 13b is in contact with the wall 32, and (3) the root part 13a, the root part 12c, the connection part 12e, part of the middle part 12b, and part of parasitic element pair 15 are in contact with the wall 31.
  • the antenna 10 can be fixed to the support 30 by an existing method as appropriate.
  • the antenna 10 can be adhered to the support 30 with use of fixing means such as a double-sided adhesive tape or a resin adhesive.
  • the support 30 can be, for example, arranged such that the wall 31 and the wall 36 have respective protrusions, and the antenna 10 can be hooked on the protrusions.
  • the tip part 12a of the element 12 of the antenna 10 is preferably caused to overlap the rear end of the roof 120 so as to increase radiant gain in a direction across the roof 120 from the rear end of the roof 120, that is, in the frontal direction of the automotive body 101.
  • the tip part 12a is preferably caused to overlap the electric conductor plate 50.
  • a region of the antenna 10 which region overlaps the electric conductor plate 50 will be referred to as an overlapping region R3.
  • a length of the tip part 12a which length is measured along a direction in which the element 12 extends (y-axis direction in the coordinate system illustrated in Fig. 4 ) will be referred to as a length L1.
  • a length of part, included in the overlapping region R3, of the tip part 12a which length is measured along the direction in which the element 12 extends will be referred to as a length L2.
  • the antenna 10 includes the parasitic element 14 which surrounds the tip part 12a. Accordingly, even in a case where the length L2 is changed, it is possible to suppress a change in capacitance formed between the element 12 and the electric conductor plate 50, provided that 0 (zero) ⁇ L2 ⁇ L1. Therefore, according to the antenna 10, it is possible to suppress dependency of the input impedance on an area of the overlapping region R3.
  • the antenna 10 is a highly versatile antenna, as compared with a conventional antenna, and it is possible to mount the antenna 10 on various types of automobiles without changing a design of the antenna 10.
  • it is not necessary to change (optimize) the design of the antenna 10 in accordance with a type of an automobile on which the antenna 10 is to be mounted it is possible to suppress a production cost.
  • FIG. 5 is a perspective view of the automotive body 101 on which the antenna 10 is mounted.
  • (b) of Fig. 5 is an enlarged plan view of the automotive body 101 illustrated in (a) of Fig. 5 .
  • the automotive body 101 is a hatchback type automotive body.
  • an outer plate (body panel) including the roof 120 is constituted by a metallic member such as a steel plate or an aluminum plate, and the roof 120 has a substantially horizontal surface. That is, the roof 120 lies along a horizontal plane and intersects with an up-and-down direction of the automotive body 101.
  • the roof 120 is a specific example of the electric conductor plate 50 illustrated in Fig. 3 .
  • a direction along the roof 120 is synonymous with a direction along the horizontal plane (xy plane in a coordinate system illustrated in Fig. 5 ), and a direction perpendicular to the roof 120 is synonymous with a direction perpendicular to the horizontal plane.
  • the antenna 10 is mounted at the rear end of the roof 120 in a state where the antenna 10 is housed in the spoiler 116 which functions as a housing. Therefore, the antenna 10 constitutes an on-vehicle antenna device 110 together with the coaxial cable 20, the support 30, and the spoiler 116.
  • a hatch gate 121 of the automotive body 101 is made up of a hatch gate panel 121a which constitutes a lower part of the hatch gate 121, a frame body 121c which constitutes an upper part of the hatch gate 121, and a rear glass 121 b.
  • the frame body 121 c is made up of two vertical poles and two beams, and the rear glass 121b is fitted in the frame body 121 c.
  • One of the two beams of the frame body 121 c which one is adjacent to the roof 120 (upper one of the two beams) is attached to the rear end of the roof 120 with use of a hinge (not illustrated).
  • Each of the hatch gate panel 121 a and the frame body 121 c is constituted by a metallic member.
  • the spoiler fixing section 121 d is provided to part of the upper one of the two beams of the frame body 121 c. Part of the upper one of the two beams of the frame body 121 c is caused to protrude rearward, and the part thus protruding is used as the spoiler fixing section 121d.
  • the spoiler fixing section 121 d is constituted by a metallic member, as with the case of the frame body 121 c. A surface of the spoiler fixing section 121 d to which surface the spoiler 116 is attached faces substantially in a zenith direction and lies along the horizontal plane, as with the case of the surface of the roof 120. As such, the spoiler fixing section 121d constitutes a rear end part of the roof 120.
  • the spoiler fixing section 121d is constituted by a metallic member which is integrally formed with the frame body 121 c. Note, however, that the spoiler fixing section 121d can be constituted by a metallic member which is formed separately from the frame body 121c and is fixed to the frame body 121c with use of a bolt or the like.
  • the spoiler 116 is attached to the spoiler fixing section 121d with use of fixing means (e.g., a bolt or the like, not illustrated). In a case where the spoiler 116 is fixed to the spoiler fixing section 121d, an upper surface of the spoiler 116 becomes substantially flush with an entire upper surface of the roof 120.
  • the spoiler 116 has functions of improving an appearance of the automotive body 101, improving an aerodynamic characteristic of the automotive body 101, and the like, and also functions as a housing of the on-vehicle antenna device 110. In the spoiler 116, the antenna 10 and a stop lamp 119 are incorporated.
  • the spoiler 116 is made of a dielectric substance (e.g., resin), and transmits an electromagnetic wave.
  • the antenna 10 is arranged at a location inside the spoiler 116 at which location the antenna 10 does not interfere with the stop lamp 119. Specifically, the antenna 10 is arranged on a left side of the stop lamp 119 so as to avoid the stop lamp 119 which is arranged in the middle, in a right-and-left direction, of the spoiler 116.
  • Fig. 6 is a graph showing frequency dependency of a VSWR (Voltage Standing Wave Ratio) of an antenna 10.
  • the frequency dependency of the VSWR will be referred to a VSWR characteristic.
  • the antenna 10 of the Example was designed so as to be targeted for a frequency band of not less than 698 MHz and not more than 960 MHz, that is, a lower frequency band out of a frequency band for LTE.
  • the antenna 10 of the Example was obtained by arranging the antenna 10 illustrated in Fig. 1 such that (i) a length of the substrate 11 was 173 mm and (ii) a width of the substrate 11 was 40 mm.
  • Fig. 7 is a plan view schematically illustrating a configuration of an antenna 60 in accordance with a Comparative Example for comparison with the antenna 10.
  • the antenna 60 included a substrate 61, an element 62 provided on one of surfaces of the substrate 61, and an element 63 provided on the one of the surfaces of the substrate 61.
  • the element 62 was connected to an outer electric conductor (cold side electric conductor) of a coaxial cable, as with the case of an element 12 of the antenna 10.
  • the element 63 was connected to a center electric conductor (hot side electric conductor) of the coaxial cable, as with the case of an element 13 of the antenna 10.
  • the antenna 60 had a configuration identical to that of an antenna 91 B illustrated in Fig. 15 of Patent Literature 1. Therefore, the antenna 60 will not be described here in detail.
  • the length L3 and the length L4 of the antenna 60 correspond to the length L1 and the length L2, respectively, of the antenna 10.
  • Fig. 8 is a graph showing a VSWR characteristic of the antenna 60.
  • an antenna in accordance with an aspect of the present invention is an antenna including: a first element; a second element; a first parasitic element which surrounds, on three sides, one of ends of the first element which one is farther from a feed region; and a second parasitic element and a third parasitic element between which a middle part of the first element is sandwiched, each of the second parasitic element and the third parasitic element being galvanically insulated from the first parasitic element.
  • the antenna a given capacitance is formed between the first parasitic element and the one of the ends of the first element, which one is farther from the feed region. Therefore, in a case where the antenna is arranged so that the one of the ends of the first element overlaps an electric conductor plate (for example, an electric conductor plate constituting a roof which is part of an automotive body of an automobile), it is possible to suppress a change in capacitance between the first element and the electric conductor plate even in a case where an area of a region of the first element which region overlaps the electric conductor plate (hereinafter, referred to as an overlapping region) changes. As a result, according to the antenna, it is possible to suppress dependency of input impedance on the area of the overlapping region.
  • an electric conductor plate for example, an electric conductor plate constituting a roof which is part of an automotive body of an automobile
  • the second parasitic element and the third parasitic element it is possible to suppress reflection caused by mismatch between (i) impedance between the middle part and the second and third parasitic elements and (ii) impedance of a coaxial cable.
  • the antenna is capable of having desired input impedance, regardless of how large or small the area of the overlapping region is. It is therefore possible to provide an antenna which is used in a state where the antenna is arranged so as to be adjacent to an electric conductor plate and which has desired input impedance independent of an area of a region of an element which region overlaps the electric conductor plate.
  • the antenna in accordance with an aspect of the present invention is arranged so as to further including: a feed cable which is connected to the first element and the second element, the feed cable being made up of a cold side electric conductor and a hot side electric conductor, the first element being connected to the cold side electric conductor of the feed cable, the second element being connected to the hot side electric conductor of the feed cable.
  • the antenna in accordance with an aspect of the present invention is arranged such that the first element has, at the other one of the ends of the first element which other one is closer to the feed region, a root part having a width greater than that of the other part of the first element.
  • the root part of the first element is part of the first element which part is most adjacent to the second element. Since a width of part of the first element which part is adjacent to the second element is greater than that of the other part of the first element, the first element is capable of operating suitably as a cold side element.
  • the fact that the first element has the root part allows an increase in resonance frequency of the antenna. Therefore, it is possible to expand an operation band of the antenna.
  • the antenna in accordance with an aspect of the present invention is arranged such that a gap between the root part and the second parasitic element and a gap between the root part and the third parasitic element are each arranged so as to become wider as extending from a center side of the root part toward an outer side of the root part.
  • the antenna in accordance with an aspect of the present invention is arranged such that the first parasitic element has (i) a first extending part which extends along an outer side of the second parasitic element and (ii) a second extending part which extends along an outer side of the third parasitic element.
  • the first extending part and the second extending part of the first parasitic element which is virtually fed with electric power via a tip part of the first element that is adjacent to the first parasitic element, function as antenna elements. This allows an increase in resonance frequency of the antenna. Therefore, it is possible to expand the operation band of the antenna.
  • the antenna in accordance with an aspect of the present invention is arranged such that the first extending part and the second extending part are different from each other in virtual electrical length.

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Details Of Aerials (AREA)
EP17159144.9A 2017-02-02 2017-03-03 Antenne Withdrawn EP3358675A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3102615A1 (fr) * 2019-10-23 2021-04-30 Renault S.A.S Véhicule comprenant un boitier muni d’une antenne
CN114128042A (zh) * 2019-07-22 2022-03-01 马自达汽车株式会社 车辆的上部结构

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EP1469553A1 (fr) * 2003-04-15 2004-10-20 Hewlett-Packard Development Company, L.P. Dispositif d'antenne monopole
US20070030200A1 (en) * 2005-08-04 2007-02-08 Heng Chew C Multi-band antenna structure
US20120262351A1 (en) * 2010-06-10 2012-10-18 Panasonic Corporation Antenna device and display device
US20150022401A1 (en) * 2013-07-18 2015-01-22 Nvidia Corporation Antenna system and an electronic device including the same
CN105024150A (zh) * 2015-05-11 2015-11-04 云南大学 一种应用于WLAN和WiMAX的三频段天线
US20160218421A1 (en) * 2015-01-23 2016-07-28 Chiun Mai Communication Systems, Inc. Antenna structure for electronic device
WO2016125876A1 (fr) 2015-02-05 2016-08-11 株式会社フジクラ Dispositif d'antenne monté sur véhicule

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1469553A1 (fr) * 2003-04-15 2004-10-20 Hewlett-Packard Development Company, L.P. Dispositif d'antenne monopole
US20070030200A1 (en) * 2005-08-04 2007-02-08 Heng Chew C Multi-band antenna structure
US20120262351A1 (en) * 2010-06-10 2012-10-18 Panasonic Corporation Antenna device and display device
US20150022401A1 (en) * 2013-07-18 2015-01-22 Nvidia Corporation Antenna system and an electronic device including the same
US20160218421A1 (en) * 2015-01-23 2016-07-28 Chiun Mai Communication Systems, Inc. Antenna structure for electronic device
WO2016125876A1 (fr) 2015-02-05 2016-08-11 株式会社フジクラ Dispositif d'antenne monté sur véhicule
CN105024150A (zh) * 2015-05-11 2015-11-04 云南大学 一种应用于WLAN和WiMAX的三频段天线

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114128042A (zh) * 2019-07-22 2022-03-01 马自达汽车株式会社 车辆的上部结构
FR3102615A1 (fr) * 2019-10-23 2021-04-30 Renault S.A.S Véhicule comprenant un boitier muni d’une antenne

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