EP2273608A1 - Fahrzeugglasantenne - Google Patents

Fahrzeugglasantenne Download PDF

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Publication number
EP2273608A1
EP2273608A1 EP10167723A EP10167723A EP2273608A1 EP 2273608 A1 EP2273608 A1 EP 2273608A1 EP 10167723 A EP10167723 A EP 10167723A EP 10167723 A EP10167723 A EP 10167723A EP 2273608 A1 EP2273608 A1 EP 2273608A1
Authority
EP
European Patent Office
Prior art keywords
antenna
antenna element
vehicle
glass
bend
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Withdrawn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
EP10167723A
Other languages
English (en)
French (fr)
Inventor
Hidetoshi Oka
Hikaru Mizukami
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.)
Nippon Sheet Glass Co Ltd
Original Assignee
Nippon Sheet Glass Co 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 Nippon Sheet Glass Co Ltd filed Critical Nippon Sheet Glass Co Ltd
Publication of EP2273608A1 publication Critical patent/EP2273608A1/de
Withdrawn legal-status Critical Current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
    • H01Q1/12—Supports; Mounting means
    • H01Q1/1271—Supports; Mounting means for mounting on windscreens
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/1271—Supports; Mounting means for mounting on windscreens
    • H01Q1/1278—Supports; Mounting means for mounting on windscreens in association with heating wires or layers

Definitions

  • the present invention relates to an antenna provided on a window glass of a vehicle, and in particular relates to a glass antenna for a vehicle which is suitable for receiving signals in the digital television band.
  • Digital television (DTV) antennas mounted in vehicles primarily assume the configuration of a film mounted on the window glass of a vehicle due to considerations of installation space and outward appearance.
  • Automobile high-frequency glass antennas assuming the form of a film installed on the window glass of a vehicle are known in the art; e.g. as disclosed in Japanese Patent Application Laid-Open Publication No. 2008-22538 ( JP-A 2008-22538 ).
  • FIG. 15 hereof shows the glass antenna disclosed in JP-A 2008-22538 .
  • An antenna conductor 100 shown in FIG. 15 is formed on a windshield 110.
  • the antenna conductor 100 comprises a first antenna element 101, a second antenna element 102, a first connecting conductor 103, and a loop-forming element 104.
  • a U-shaped conductor pattern is formed from the first antenna element 101, the second antenna element 102, and the first connecting conductor 103.
  • the first antenna element 101 and a feeder 105 are connected via a second connecting conductor 106, and a loop is formed by the first antenna element 101, the first connecting conductor 103, and the loop-forming element 104.
  • the antenna conductor 100 since the antenna conductor 100 has a loop, the antenna conductor can have a plurality of resonant frequencies, and it is possible to achieve a level of high antenna gain and a high FB ratio (front-to-back power ratio) without compromising the aesthetic appearance, even in a wideband broadcasting frequency.
  • a high FB ratio front-to-back power ratio
  • the distance between the second antenna element 102 and a body edge composed of metal is 1/4 of the wavelength or less, the radiation impedance decreases, the radiation efficiency of the antenna is reduced, and restrictions are imposed on the bandwidth and the directional characteristics.
  • the second antenna element 102 serving as the main antenna must be separated from the body edge of the vehicle roof by a distance of approximately 100 mm.
  • a glass antenna for a vehicle mounted on a window glass provided to a vehicle body so as to close an opening in the vehicle body, which glass antenna comprises an antenna element having at least a double-bend pattern.
  • providing the glass antenna for a vehicle with at least a double-bend pattern extending along the edge of the opening of the vehicle body thus makes it possible to improve reception sensitivity while minimizing the loss of impedance caused by placing the antenna in close proximity to the body edge of the vehicle.
  • the antenna element is comprised of a linear first antenna element which extends from a feeder into the opening and along an edge of the opening, a second antenna element which bends approximately 180° from a distal end of the first antenna element and extends facing the first antenna element, and a third antenna element which folds approximately 180 degrees from a distal end of the second antenna element and extends facing the second antenna element.
  • a double-bend pattern can be formed by the first, second, and third antenna elements, making it possible to improve reception sensitivity while minimizing the loss of impedance caused by placing the antenna element in close proximity to the body edge of the vehicle.
  • the third antenna element is disposed at a distance from the edge of the opening that is equal to or less than one-sixteenth of one wavelength of a predetermined frequency.
  • the third antenna element positioned at the lowest part of the glass antenna is disposed at a short distance equal to or less than one-sixteenth of one wavelength of a predetermined frequency from the edge of the opening, the third antenna element does not interfere with the field of vision during driving.
  • the length of the third antenna element is set to a value obtained by multiplying a shortening rate by one-half of one wavelength of the predetermined frequency.
  • the antenna pattern is accordingly of simple design.
  • a glass antenna for a vehicle according to the present invention can be mounted on a window glass of a vehicle.
  • a vehicle 10 is provided with window glass composed of a windshield 13 fitted between left and right front pillars 12L, 12R (L is a symbol indicating left, R is a symbol indicating right; hereinafter likewise) of a vehicle body 11, a rear window 15 fitted between rear pillars 14L, 14R, front door windows 17L, 17R raisably and lowerably mounted to front doors 16L, 16R, and rear door windows 19L, 19R raisably and lowerably mounted to rear doors 18L, 18R, as shown in FIG. 1 .
  • a glass antenna 20 for a vehicle can be mounted on any of the window glasses described above, but in the present embodiment, the antenna is provided in substantially the top center part of the windshield 13.
  • the glass antenna 20 for a vehicle is primarily a DTV antenna designed in order to receive radio waves of terrestrial digital broadcasting using a terrestrial UHF (ultra-high frequency) band for an in-car television.
  • the details of the glass antenna 20 for a vehicle are described in FIG. 2 .
  • the glass antenna 20 for a vehicle is mounted to the window glass 13 provided to the vehicle body 11 so as to close an opening in the vehicle body 11, as shown in FIG. 2(a) .
  • the glass antenna 20 for a vehicle includes an impedance adjustment element 20a as an antenna body, a main antenna element 20b, and a feeder 20c, which are mounted in close proximity to an edge of the opening of the vehicle body 11 (hereinafter referred to as a body edge 24).
  • the numeral 25 indicates a glass edge of the window glass 13 installed in the interior of the vehicle body 11.
  • the impedance adjustment element 20a is described in further detail.
  • the impedance adjustment element 20a is composed of a linear conductor, and includes a first antenna element 21 and a second antenna element 22, as shown in FIG. 2(b) .
  • the first antenna element 21 is a linear conductor formed extending along the body edge 24 from the feeder 20c.
  • the second antenna element 22 is a linear conductor formed bent back 180° from a distal end position of the first antenna element 21 and extending facing the first antenna element 21.
  • the two elements herein extend substantially parallel facing each other.
  • the main antenna element 20b shown as a third antenna element is a linear conductor formed bent back at approximately 180° from the distal end of the second antenna element 22 constituting the impedance adjustment element 20a and extending facing the second antenna element 22.
  • the elements extend substantially parallel facing each other.
  • the bend dimension a of the first and second antenna elements 21, 22 constituting the impedance adjustment element 20a is 100 mm
  • the element length d of the main antenna element 20b is 150 mm
  • the conductor gaps c between the first and second antenna pattern and between the impedance adjustment element 20a (the second antenna element 22) and the main antenna element 20b are both 5 mm.
  • the reason the conductor gaps c are 5 mm because there is a tradeoff in terms of design between improving the performance or the size of the antenna (reducing the installation space), with size being given priority from an optimal range of 3 mm to 20 mm for the conductor gaps.
  • the distance b between the main antenna element 20b and the body edge 24 of the vehicle body 11 is optimally 30 mm or less. The basis for this is described hereinafter.
  • the gap e between the feeding point 20c and the bending point of the impedance adjustment element 20a is optimally 5 mm.
  • the dimensions of the feed point (terminal 20b) used herein are preferably 20 mm ⁇ 12 mm, and the antenna wire width is 0.2 mm to 1.0 mm.
  • Designing the impedance adjustment element 20a with a double-bend pattern is equivalent to electrically adding impedance. Additionally the distance b to the body edge 24 of the vehicle body 11, which had been 100 mm in conventional practice, is reduced to 30 mm.
  • the inventors measured antenna sensitivity while varying the bend dimension a of the impedance adjustment element 20a shown in FIG. 2(b) from 0 to 150 mm and varying the frequency from 400 MHz to 800 MHz.
  • FIGS. 3(d) though (d) For ease of reference, a representative example of the impedance adjustment element 20a is shown in FIGS. 3(d) though (d). Specifically, when the bend dimension a is varied while the antenna length d is kept constant, the shape of the impedance adjustment element 20a changes as shown in (a) through (d), for example.
  • FIG. 4 shows the result of varying the bend dimension a of the impedance adjustment element 20a from 0 to 150 mm and plotting the corresponding sensitivities on a graph.
  • the horizontal axis represents the frequency [MHz] centered on the DTV band (473 MHz to 713 MHz), and the vertical axis represents relative sensitivity [dBd].
  • the sensitivity curves when the bend dimension a has been varied among 0 (no bend), 25 mm, 50 mm, 75 mm, 80 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, and 150 mm are indicated by a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, and a14, respectively.
  • the curve indicated by the bold line a8 shows the sensitivity obtained in the DTV band, which is particularly stable in comparison with the thin lines a1 to a7 and a9 to a14.
  • the ratio between the maximum voltage and the minimum voltage of a standing wave occurring at the feeding point 20c is indicated by the VSWR (voltage standing wave ratio), representing the degree of matching between characteristic impedance and load impedance of the feeder line.
  • the VSWR is 1.
  • FIGS. 5 through 10 show the VSWR at points of 473 MHz, 575 MHz, 586 MHz, and 713 MHz, wherein the frequency (in MHz) is plotted on the horizontal axis, the VSWR is plotted on the vertical axis, with 400 MHz being the measurement starting point, and 800 MHz being the measurement ending point.
  • the 473 MHz frequency shown in FIG. 4 is used for the frequency in the hypothetical description.
  • the 473 MHz frequency has the worst impedance within the DTV band (473 to 713 MHz). Therefore, if a description is provided for 473 MHz, which is the lowest, other frequencies that are more favorable will not need to be described.
  • the bend dimension can be found by multiplying one wavelength of the predetermined frequency (design frequency)] by (1/4) by the shortening factor.
  • the value of one wavelength of the predetermined frequency (design frequency) is determined by dividing 300 by 473.
  • the bend dimension a which is obtained by multiplying (300/470) by (1/4) by 0.6, is thus 95 mm.
  • 100 mm is the preferred value of the optimal bend dimension.
  • the impedance adjustment element 20a with at least a double-bend pattern extending along the edge of an opening in the vehicle body 11 makes it possible to improve reception sensitivity while minimizing the loss of impedance caused by placing the impedance adjustment element 20a in close proximity to the body edge 24.
  • the optimal value for the bend dimension in such circumstances is obtained by multiplying the shortening factor by one-fourth of one wavelength of a predetermined frequency.
  • FIG. 11 shows a sensitivity measurement pattern according to the distance between the main antenna element 20b and the body edge 24, and FIG. 12 shows a graph representing the variation in sensitivity.
  • the impedance adjustment element 20a is provided with a bend of a dimension which matches the frequency at which sensitivity is inadequate due to impedance mismatching, but since matching is the purpose of the bend, the impedance adjustment element 20a must be placed in close proximity to the body edge 24 so as not to form an antenna receiving element.
  • the main antenna element 20b which is the third antenna element positioned at the lowest point of the bending pattern, is subjected to impedance adjustment by the impedance adjustment element 20a.
  • the main antenna element 20b therefore can be disposed in close proximity to the body edge 24 without impeding the field of vision during driving.
  • FIG. 13 shows the sensitivity measurement pattern and its dimensions resulting from varying the element length of the main antenna element 20b
  • FIG. 14 shows a graph representing the relationship between element length and sensitivity.
  • the manner in which the sensitivity changes when the length (element length) d' of the main antenna element 20b shown in FIG. 13 is varied in 5 mm increments from 130 mm to 170 mm is indicated in FIG. 14 as d1, d2, d3, d4, d5, d6, d7, d8, and d9, respectively.
  • the antenna pattern is more readily designed because the element length of the main antenna element 20b is set to a value obtained by multiplying the shortening factor by one-half of one wavelength of a predetermined frequency.
  • the present invention can be applied to the DTV band within Japan
  • the present invention can also be applied to digital television bands in other countries, and is suitable as means for optimizing resonant impedance and improving reception sensitivity in cases in which the glass antenna for a vehicle is installed in close proximity to the body edge in order to achieve a favorable field of vision during driving.

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EP10167723A 2009-07-08 2010-06-29 Fahrzeugglasantenne Withdrawn EP2273608A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2009162239A JP5285521B2 (ja) 2009-07-08 2009-07-08 車両用ガラスアンテナおよび窓ガラス

Publications (1)

Publication Number Publication Date
EP2273608A1 true EP2273608A1 (de) 2011-01-12

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EP10167723A Withdrawn EP2273608A1 (de) 2009-07-08 2010-06-29 Fahrzeugglasantenne

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EP (1) EP2273608A1 (de)
JP (1) JP5285521B2 (de)
CN (1) CN101950853A (de)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013131889A (ja) * 2011-12-21 2013-07-04 Central Glass Co Ltd 車両用ガラスアンテナ
JP6137191B2 (ja) * 2012-10-25 2017-05-31 旭硝子株式会社 車両用窓ガラスおよびその取付構造
US10714809B2 (en) * 2016-05-10 2020-07-14 AGC Inc. Antenna for vehicle
CN115335525A (zh) * 2020-03-24 2022-11-11 国立大学法人岩手大学 经修饰的通道视紫红质

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4791425A (en) * 1985-05-20 1988-12-13 Toyota Jidosha Kaisha Window antenna for a vehicle
EP1100144A2 (de) * 1999-11-10 2001-05-16 Nippon Sheet Glass Co., Ltd. Glasantenne für Fahrzeug
JP2002299932A (ja) * 2001-04-03 2002-10-11 Central Glass Co Ltd 車両用のガラスアンテナ
US20040212541A1 (en) * 2003-04-28 2004-10-28 Apostolos John T. Ferrite loaded meander line loaded antenna
EP1732160A1 (de) * 2005-06-10 2006-12-13 Matsushita Electric Industrial Co., Ltd. Doppelbandantenne für den digitalen Tonrundfunk
JP2008022538A (ja) 2006-06-12 2008-01-31 Asahi Glass Co Ltd 自動車用高周波ガラスアンテナ
US20080158074A1 (en) * 2006-12-28 2008-07-03 Agc Automotive Americas R&D, Inc. Multi-Band Strip Antenna

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5512481Y2 (de) * 1974-07-16 1980-03-19
JP2004242153A (ja) * 2003-02-07 2004-08-26 Honda Motor Co Ltd 車載アンテナ

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4791425A (en) * 1985-05-20 1988-12-13 Toyota Jidosha Kaisha Window antenna for a vehicle
EP1100144A2 (de) * 1999-11-10 2001-05-16 Nippon Sheet Glass Co., Ltd. Glasantenne für Fahrzeug
JP2002299932A (ja) * 2001-04-03 2002-10-11 Central Glass Co Ltd 車両用のガラスアンテナ
US20040212541A1 (en) * 2003-04-28 2004-10-28 Apostolos John T. Ferrite loaded meander line loaded antenna
EP1732160A1 (de) * 2005-06-10 2006-12-13 Matsushita Electric Industrial Co., Ltd. Doppelbandantenne für den digitalen Tonrundfunk
JP2008022538A (ja) 2006-06-12 2008-01-31 Asahi Glass Co Ltd 自動車用高周波ガラスアンテナ
US20080158074A1 (en) * 2006-12-28 2008-07-03 Agc Automotive Americas R&D, Inc. Multi-Band Strip Antenna

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Publication number Publication date
CN101950853A (zh) 2011-01-19
JP2011019081A (ja) 2011-01-27
JP5285521B2 (ja) 2013-09-11

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