Vehicular glass antenna

Abstract

Provided is a vehicular glass antenna constituting a diversity antenna which is used in an electric vehicle and not easily affected by electromagnetic noise. The vehicular glass antenna (A), which is provided in an electric vehicle (1) that can travel using the driving force of a motor that receives power supplied from a battery, comprises: a glass plate (2) that separates the inside of the electric vehicle (1) from the outside; and a first antenna element (10) that is fixed to a plate surface (2a) of the glass plate (2) and can receive radio waves propagating in the air outside the electric vehicle (1). The first antenna element (10) constitutes a diversity antenna in cooperation with a second antenna element (20) which is capable of receiving radio waves and provided outside the electric vehicle (1) with a blocking unit (7) therebetween, the blocking unit being capable of blocking electromagnetic noise emitted from a transformer disposed between the battery and an apparatus that is supplied with power from the battery.

Description

Vehicle glass antenna

[0001] The present invention relates to a glass antenna for a vehicle.

[0002] Automobiles are equipped with antennas for receiving broadcast waves and transmitting and receiving various systems. As the vehicle moves, the reception conditions for these radio waves change from moment to moment. In order to stabilize the reception conditions for radio waves, diversity antennas that receive radio waves with multiple antennas are sometimes adopted.

[0003] Patent Document 1 describes a vehicle glass antenna that can provide good diversity reception of FM broadcast waves even when the space above the defogger on the rear window of a vehicle is narrow by providing two antennas in the space. This vehicle glass antenna consists of two antennas for FM broadcast waves arranged in the space above the defogger on the rear window of a vehicle. Each antenna has a power feeder arranged spaced apart on the left and right sides of the upper edge of the rear window, a vertical wire connected to the power feeder and hanging down, and a horizontal wire connected to the lower end of the vertical wire. The horizontal wires of the two antennas are each arranged close to the heating horizontal wire at the top of the defogger and are capacitively coupled to the top heating horizontal wire. At least one auxiliary wire for adjusting the directional characteristics is connected to the vertical wire or the power feeder of at least one of the two antennas.

[0004] Patent Document 2 describes a vehicle glass antenna that is installed in the margin of a defogger on the rear window of an automobile, and that receives AM and FM broadcast waves with high gain and excellent directional characteristics. This antenna includes an AM broadcast wave antenna having a plurality of horizontal wires spaced apart and at least two vertical wires perpendicular to the horizontal wires, with an AM broadcast wave feed point extending from the uppermost horizontal wire via a lead wire. Another FM broadcast wave antenna extends clockwise and counterclockwise from two FM feed points located on either side of the AM feed point along a portion of the outermost periphery of the AM broadcast wave antenna. This FM broadcast wave antenna is configured to effectively achieve diversity reception by extending the second vertical wires at different lengths.

[0005] Patent Document 3 describes a vehicle glass antenna (an automobile diversity glass antenna in Patent Document 3) suitable for receiving AM broadcasts, FM broadcasts, and television broadcasts. This glass antenna has a first antenna conductor capacitively coupled to a defogger on the rear window of the vehicle and a second antenna conductor that is not capacitively coupled to the defogger, and connects the second antenna conductor to the defogger via a capacitor selected to provide high impedance in the AM broadcast wave band, and performs diversity reception using the first antenna conductor and the second antenna conductor.

[0006] JP 2012-248981 A JP 2010-109958 A JP 9-130120 A

[0007] Recently, there has been an increase in automobiles equipped with motors as a driving source (such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and fuel cell electric vehicles (FCEVs), hereinafter also referred to as "electric vehicles"). Electric vehicles have a high-voltage battery installed inside the vehicle, and a DC-DC converter provides voltage for operating various on-board electronic devices. However, electromagnetic noise generated during voltage conversion interferes with signal reception by a diversity antenna. The vehicular glass antennas described in Patent Documents 1 to 3 have two antennas for diversity reception both located on the rear window of the vehicle.

[0008] Recent diversity antennas use a phase diversity method for processing received signals, which calculates interference from the difference between the received signals of two antennas and subtracts the interference from the received signals of the two antennas. Therefore, it is desirable that the performance difference between the two antennas constituting the diversity reception, i.e., the difference in received signal strength, should not be too large. On the other hand, it is not desirable for the distance between the two antennas to be too close. If the distance is too short, the difference between the received signal and interference at each antenna will be small, which may make it difficult to calculate the interference.

[0009] Therefore, there is a demand for a vehicle glass antenna that is used in an electric vehicle and that constitutes a diversity antenna that is less susceptible to the effects of electromagnetic noise.

[0010] One embodiment of the vehicle glass antenna according to the present invention is a vehicle glass antenna provided on an electric vehicle that can run by the driving force of a motor supplied with power from a battery, and includes a glass plate that separates the interior and exterior of the electric vehicle, and a first antenna element that is fixed to a plate surface of the glass plate and is capable of receiving radio waves propagating through the air outside the electric vehicle, and the first antenna element is provided on the exterior of the electric vehicle via a blocking section that blocks electromagnetic noise emitted from a transformer that is arranged between the battery and a device that receives power from the battery, and cooperates with a second antenna element that is capable of receiving the radio waves to form a diversity antenna.

[0011] According to this embodiment, the vehicle glass antenna includes a glass plate separating the interior and exterior of an electric vehicle and a first antenna element capable of receiving radio waves propagating through the air outside the electric vehicle. The first antenna element is provided outside the electric vehicle via a shielding portion capable of blocking electromagnetic noise emitted from a transformer disposed between the battery and a device powered by the battery, and cooperates with a second antenna element capable of receiving radio waves to form a diversity antenna. In this way, the first antenna element fixed to the glass plate cooperates with the second antenna element receiving radio waves via the shielding portion to form a diversity antenna, so that the first antenna element is less susceptible to electromagnetic noise from the transformer of the electric vehicle and can receive radio waves stably.

[0012] In another embodiment of the glass antenna for a vehicle according to the present invention, the blocking portion is made of a metal plate.

[0013] According to this embodiment, since the blocking portion is made of metal, it is possible to reliably block electromagnetic noise emitted from the transformer and suppress the influence of the electromagnetic noise on the second antenna element.

[0014] In another embodiment of the glass antenna for a vehicle according to the present invention, the blocking portion is a metal exterior panel of the electric vehicle.

[0015] According to this embodiment, when the blocking portion is a metal exterior panel of the electric vehicle, there is no need to provide a separate structure for blocking electromagnetic noise, and the electric vehicle can be manufactured at low cost.

[0016] In another embodiment of the glass antenna for a vehicle according to the present invention, the diversity antenna is used for a phase diversity receiving system.

[0017] According to this embodiment, if the diversity antenna is of a phase diversity receiving type, it is possible to receive radio waves stably even in a location where multipath fading is likely to occur, such as a canyon between buildings.

[0018] In another embodiment of the glass antenna for a vehicle according to the present invention, the frequency band includes a frequency band used for FM radio broadcasting.

[0019] According to this embodiment, FM radio broadcasts can be received stably.

[0020] In another embodiment of the vehicle glass antenna according to the present invention, the second antenna element has a power supply portion and an element, and is arranged in this order, facing away from the blocking portion.

[0021] According to this embodiment, the performance of the second antenna element is improved, and radio waves can be received stably.

[0022] In another embodiment of the glass antenna for a vehicle according to the present invention, the first antenna element is disposed at a position where it can be capacitively coupled with the metal exterior panel.

[0023] According to this embodiment, the reception performance of the first antenna element can be changed by changing the coupling capacitance between the first antenna element and the metal exterior panel.

[0024] In another embodiment of the glass antenna for a vehicle according to the present invention, the first antenna element has a receiving gain equal to that of the second antenna element.

[0025] According to this embodiment, if the reception gains of the first antenna element and the second antenna element are equal, the diversity antenna performance can be fully utilized, and radio waves can be received stably.

[0026] In another embodiment of the vehicle glass antenna according to the present invention, an outer edge of the glass plate is fixed so as to cover an opening area formed in the metal exterior panel of the electric vehicle, and the first antenna element includes a horizontal element that is arranged perpendicular to the opening edge of the opening area in the left-right direction of the electric vehicle and at a distance along the plate surface of the glass plate of within 20 mm.

[0027] According to this embodiment, by placing the horizontal element perpendicular to the left-right direction of the electric vehicle and at a distance of 20 mm or less along the surface of the glass plate, the reception gain can be made equal to that of the second antenna element, and radio waves can be received stably.

[0028] In another embodiment of the glass antenna for a vehicle according to the present invention, the horizontal element is disposed closer to the center of the glass plate than the opening edge of the opening region.

[0029] According to this embodiment, by arranging the horizontal element closer to the center of the glass plate than the opening edge of the opening area, the reception gain can be made equal to that of the second antenna element, allowing for stable reception of radio waves.

[0030] In another embodiment of the glass antenna for a vehicle according to the present invention, the horizontal element is arranged on the outer edge side of the glass plate with respect to the opening edge of the opening region.

[0031] According to this embodiment, by arranging the horizontal element on the outer edge side of the glass plate relative to the opening edge of the opening area, the reception gain can be made equal to that of the second antenna element, enabling stable reception of radio waves.

[0032] In another embodiment of the glass antenna for a vehicle according to the present invention, the glass plate is a rear glass of the electric vehicle, and the blocking portion is a roof.

[0033] According to this embodiment, when the glass plate is the rear glass of an electric vehicle and the blocking portion is the roof, the first antenna element does not interfere with driving, no special configuration is required for the blocking portion to block electromagnetic noise, radio waves can be received stably, and the electric vehicle can be manufactured inexpensively.

[0034] In another embodiment of the glass antenna for a vehicle according to the present invention, the first antenna element is disposed below the rear window in the up-down direction.

[0035] According to this embodiment, it is possible to provide an appropriate distance between the first antenna element and the second antenna element, thereby making it possible to maximize the performance of the diversity antenna and receive radio waves stably.

[0036] 1 is a side view showing an electric vehicle using the vehicle glass antenna according to the present embodiment. FIG. 2 is a front view showing the vehicle glass antenna. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. FIG. 4 is a front view showing another vehicle glass antenna. FIG. 5 is a front view showing the configuration of another vehicle glass antenna. FIG. 6 is a graph showing the difference in reception gain between an antenna element and a shark fin antenna in a domestic reception frequency band. FIG. 7 is a front view showing the configuration of another vehicle glass antenna. FIG. 8 is a graph showing the difference in reception gain between an antenna element and a shark fin antenna in a reception frequency band. FIG. 9 is a front view showing the configuration of another vehicle glass antenna. FIG. 10 is a graph showing the difference in reception gain between an antenna element and a shark fin antenna in a reception frequency band. FIG. 11 is a front view showing the configuration of another vehicle glass antenna. FIG. 12 is a graph showing the difference in reception gain between an antenna element and a shark fin antenna in a reception frequency band.

[0037] Hereinafter, embodiments of the vehicle glass antenna according to the present invention will be described in detail with reference to the drawings. Note that the embodiments described below are merely examples for explaining the present invention, and the present invention is not limited to these embodiments. Therefore, the present invention can be embodied in various forms without departing from the gist of the present invention.

[0038] As shown in FIGS. 1 and 2 , a vehicle glass antenna A according to the present invention is used in an automobile (such as a hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV), battery electric vehicle (BEV), or fuel cell electric vehicle (FCEV)) equipped with a motor 3 as a driving source. Hereinafter, these automobiles will be collectively referred to as an electric vehicle 1. Hereinafter, the up-down direction of the electric vehicle 1 will be defined as the X direction, and the left-right direction with respect to the traveling direction will be defined as the Y direction. The upper side of the electric vehicle 1 in the X direction will be defined as the X1 side, and the lower side will be defined as the X2 side. Furthermore, the right side with respect to the traveling direction in the Y direction will be defined as the Y1 side, and the left side will be defined as the Y2 side.

[0039] The electric vehicle 1 is equipped with a battery 4 that supplies power to a motor 3, which serves as a drive source for traveling. The output voltage of the battery 4 is several hundred volts DC. Therefore, in order to supply power from the battery 4 to onboard electronic devices 6 (an example of a device, such as a car navigation system, radio, or audio) mounted on the electric vehicle 1 that operate at low voltages, such as 12 V DC, the output of the battery 4 must be stepped down using a DC-DC converter 5 (an example of a transformer). The switching required for this step-down operation causes the DC-DC converter 5 to emit electromagnetic noise. This electromagnetic noise may adversely affect reception of radio waves propagating through the air outside the electric vehicle 1 by an antenna provided on the electric vehicle 1. The outside of the electric vehicle 1 refers to the outer space on the opposite side of the vehicle interior 1a from a metal exterior panel 7 (an example of a shielding member or metal plate) of the electric vehicle 1. Hereinafter, the inner space, including the vehicle interior 1a, located on the opposite side of the metal exterior panel 7 from the outside will be referred to as the interior of the electric vehicle 1.

[0040] In this embodiment, a diversity antenna is used to stably receive radio waves in response to changing radio wave reception conditions while the electric vehicle 1 is traveling. The diversity antenna in this embodiment is configured to cooperate with a vehicle glass antenna A and a shark fin antenna 20 (an example of a second antenna element). The diversity antenna employs a phase diversity system that can combine desired waves and eliminate multipath fading by adjusting the amplitude and phase of the radio waves (received signals) received by the vehicle glass antenna A and the shark fin antenna 20, respectively. This improves the quality of the received signal. The diversity antenna in this embodiment is configured to receive frequencies particularly used for FM radio broadcasts. The principles of phase diversity diversity antennas are well known, so detailed description will be omitted. Note that, except for the shark fin antenna 20 shown in FIG. 3 , the transmission line 26 connecting the FM radio receiver included in the on-board electronic device 6 to the vehicle glass antenna A and the shark fin antenna 20 is not shown in FIGS. 1 to 4 .

[0041] The vehicle glass antenna A includes a rear window 2 (an example of a glass plate) of an electric vehicle 1 and an antenna element 10 (an example of a first antenna element) fixed to an inner surface 2a (an example of a plate surface) of the rear window 2 (see FIG. 3). The shark fin antenna 20 is disposed on a roof 7c (an example of a shielding portion, a metal plate) formed by a metal exterior panel 7 of the vehicle in order to reduce adverse effects of electromagnetic noise generated from inside the electric vehicle 1. This can shield electromagnetic noise radiated by the DC-DC converter 5, allowing the shark fin antenna 20 to stably receive radio waves propagating through the air outside.

[0042] 2 , the rear glass 2 is attached to a metal exterior panel 7 of the electric vehicle 1 by applying adhesive to an outer edge 2b of an inner surface 2a located inside the electric vehicle 1. In other words, the part of the rear glass 2 through which light passes is an inner region 7b (an example of an opening region) of a window frame 7a (an example of an opening edge) formed in the metal exterior panel 7. Here, the window frame 7a refers to the outer edge of the inner region 7b of the metal exterior panel 7. In other words, the window frame 7a refers to the boundary between the metal exterior panel 7 and the inner region 7b of the metal exterior panel 7.

[0043] The antenna element 10 is formed by printing and baking a conductive material, such as silver paste, onto the inner surface 2a of the rear window 2. As shown in FIGS. 2 and 3 , the antenna element 10 has a linear shape extending along the X direction and includes a power supply 12 and a horizontal conductor 14 (an example of a horizontal element) extending along the X direction. In this embodiment, the power supply 12 of the antenna element 10 is disposed outside the defog region 2c on the inner surface 2a of the rear window 2 and inside the window frame 7a. The horizontal conductor 14 is disposed outside the defog region 2c formed on the inner surface 2a of the rear window 2 and outside the window frame 7a. In other words, as shown in FIG. 2 , when viewed forward from the rear of the electric vehicle 1, the horizontal conductor 14 of the antenna element 10 is disposed so as to overlap the metal exterior panel 7. In other words, the horizontal conductor 14 of the antenna element 10 is disposed on the outer edge 2b side of the window frame 7a, which is the outer edge of the inner region 7b.

[0044] In Figure 3, the antenna element 10 formed on the inner surface 2a of the rear glass 2 and the metal exterior panel 7 are spaced apart, but this is because the thickness of the adhesive layer 8 that bonds the rear glass 2 and the metal exterior panel 7 is thicker than the thickness of the antenna element 10. In Figure 3, the thicknesses of the antenna element 10 and the adhesive layer 8 are exaggerated. In reality, the thickness of the antenna element 10 is approximately 3 μm to 30 μm, and the thickness of the adhesive layer 8 is approximately 1 mm to 15 mm.

[0045] The horizontal conductor 14 is divided into two parts. The horizontal conductor 14 located on the Y1 side is referred to as the first horizontal conductor 14a (an example of a horizontal element), and the horizontal conductor 14 located on the Y2 side is referred to as the second horizontal conductor 14b (an example of a horizontal element). The Y1-side end of the first horizontal conductor 14a is connected to the power supply 12. The second horizontal conductor 14b is not connected to the power supply 12. Each horizontal conductor 14 extends from the Y-direction end toward the center of the rear glass 2, but their central tips are spaced apart. As described above, the horizontal conductor 14 of the antenna element 10 is spaced apart from the metal exterior panel 7, but the horizontal conductor 14 of the antenna element 10 is capacitively coupled to the metal exterior panel 7.

[0046] As another example, the horizontal conductor 14 of the antenna element 10 may be disposed outside the defog region 2c on the inner surface 2a of the rear window 2 and inside the window frame 7a, as shown in FIG. 4 . In this case, when viewed from the rear to the front of the electric vehicle 1, the horizontal conductor 14 of the antenna element 10 does not overlap the metal exterior panel 7. In other words, the horizontal conductor 14 of the antenna element 10 is disposed closer to the center of the rear window 2 in the X direction than the window frame 7a, which is the outer edge of the inner region 7b. Even when the horizontal conductor 14 of the antenna element 10 is disposed in this position, the horizontal conductor 14 of the antenna element 10 is capacitively coupled to the metal exterior panel 7.

[0047] As shown in FIGS. 1 to 4 , the shark fin antenna 20 is disposed outside the electric vehicle 1 relative to the roof 7c of the metal exterior panel 7. As shown in FIG. 3 , the shark fin antenna 20 includes a power supply unit 22, an antenna unit 24 (an example of an element) connected to the power supply unit 22, and a transmission line 26 that transmits received radio waves to the on-board electronic device 6. In this embodiment, the shark fin antenna 20 is disposed in this order from the roof 7c (metal exterior panel 7) outside the electric vehicle 1 toward a direction away from the roof 7c. Because the shark fin antenna 20 is disposed outside the electric vehicle 1 relative to the roof 7c, electromagnetic noise generated inside the electric vehicle 1 (particularly the DC-DC converter 5) is blocked by the roof 7c, enabling stable radio wave reception. The roof 7c may be a sunroof or may be composed only of a metal plate. If the roof 7c is a sunroof, the shark fin antenna 20 is preferably disposed on the metal exterior panel 7 other than the glass portion.

[0048] In order for a phase diversity type diversity antenna to stably receive radio waves, it is necessary to reduce the difference (hereinafter simply referred to as the gain difference) in the reception performance (reception gain) between the antenna element 10 and the shark fin antenna 20 of the vehicle glass antenna A in the desired frequency band (76 MHz to 108 MHz used for FM radio broadcasting in this embodiment; hereinafter, this frequency band will also be referred to as the reception frequency band). Specifically, the gain difference between the antenna element 10 and the shark fin antenna 20 needs to be within ±15 dB across the entire reception frequency band, preferably within ±10 dB, and more preferably within ±5 dB. If the gain difference between the antenna element 10 and the shark fin antenna 20 is within ±5 dB across the entire reception frequency band, it can be said that the reception gains of the antenna element 10 and the shark fin antenna 20 are equivalent.

[0049] Changing the reception performance of the shark fin antenna 20 is difficult due to shape constraints. However, since the antenna element 10 is capacitively coupled to the metal exterior panel 7 as described above, the reception performance of the antenna element 10 can be changed by changing the distance d between the horizontal conductor 14 of the antenna element 10 and the window frame 7a of the metal exterior panel 7 in a direction perpendicular to the Y direction and along the inner surface 2a of the rear window 2 (hereinafter referred to as the inner surface direction) to change the coupling capacitance. The reference for the distance d (where d = 0) is where the normal to the rear window 2 contacts the window frame 7a, as shown in FIG. 3 . In order to reduce the difference in reception gain between the antenna element 10 and the shark fin antenna 20, the distance d between the horizontal conductor 14 of the antenna element 10 and the window frame 7a is preferably within ±20 mm in the inner surface direction from the reference distance. Within this range, the difference in reception gain with the shark fin antenna 20 can be reduced. In the following description, when the distance d is displayed as a plus sign, it indicates that the sensor is located outside the defog area 2c on the inner surface 2a of the rear window 2 and inside the window frame 7a, as shown in Fig. 4. When the distance d is displayed as a minus sign, it indicates that the sensor is located outside the defog area 2c on the inner surface 2a of the rear window 2 and outside the window frame 7a, as shown in Figs. 2 and 3.

[0050] The receiving frequency band of 76 MHz to 108 MHz is roughly divided into a domestic receiving frequency band of 76 to 96 MHz and an overseas receiving frequency band of 88 MHz to 108 MHz. Figures 5 to 8 show the gain difference between the shark fin antenna 20 and the shark fin antenna 20 when the distance d between the horizontal conductor 14 of the antenna element 10 and the window frame 7a in the vehicle glass antenna A is changed.

[0051] Figures 5a, 6a, 6b, 7a, and 8a show the configurations of diversity antennas in which the shape of the horizontal conductor 14 of the antenna element 10 of a vehicle glass antenna A and the distance d from the window frame 7a are changed. The antenna elements 10 shown in Figures 5a, 6a, 6b, and 7a are for the domestic reception frequency band, while the antenna element 10 shown in Figure 8a is for the overseas reception frequency band. Figures 5b, 6c, 7b, and 8b show the gain difference when using diversity antennas including each antenna element 10. Hereinafter, when distinguishing between these five types of antenna elements 10, the antenna element 10 shown in Figure 5a will be referred to as antenna element 10a. The antenna elements 10 shown in Figures 6a and 6b will be referred to as antenna element 10b and antenna element 10c, respectively. The antenna element 10 shown in Figure 7a will be referred to as antenna element 10d. The antenna element 10 shown in Figure 8a will be referred to as antenna element 10e. In any of the antenna elements 10a to 10e, the power supply portion 12 is disposed outside the defog area 2c on the inner surface 2a of the rear window 2 and inside the window frame 7a.

[0052] Figure 5a shows an antenna element 10a in which the distance d between the first horizontal conductor 14a located on the Y1 side and the window frame 7a is +45 mm, and a portion of the heating wire in the defog region 2c is used as the horizontal conductor 14. Figure 5b shows the gain difference when the antenna element 10a is used. Hereinafter, the horizontal conductor 14 consisting of a portion of the heating wire in the defog region 2c is referred to as the third horizontal conductor 14c (an example of a horizontal element). The third horizontal conductor 14c extends downward from the center of the defog region 2c and extends horizontally in both left and right directions from its extended ends. The distance d between the third horizontal conductor 14c and the window frame 7a is +25 mm. The tip of the portion of the third horizontal conductor 14c extending to the right overlaps the tip of the first horizontal conductor 14a in the vertical direction (X direction).

[0053] In the antenna element 10a shown in Fig. 5a, as shown in Fig. 5b, the gain difference exceeds +15 dB in the frequency range from 80 MHz to 84 MHz within the domestic reception frequency band of 76 MHz to 96 MHz. Therefore, the antenna element 10a is unsuitable for use as a diversity antenna for domestic FM radio broadcasts.

[0054] Figure 6a shows antenna element 10b in which the separation distance d between the horizontal conductor 14 (first horizontal conductor 14a) located on the Y1 side and the window frame 7a is +10 mm. Figure 6b shows antenna element 10c in which the separation distance d is -10 mm. Figure 6c shows the gain difference when antenna element 10b and antenna element 10c are used.

[0055] In the antenna element 10b shown in Fig. 6a, the gain difference is within ±15 dB over the entire domestic reception frequency band from 76 MHz to 96 MHz, as shown in Fig. 6c. Therefore, the antenna element 10b can be used as a diversity antenna for domestic FM radio broadcasts.

[0056] In the antenna element 10c shown in Fig. 6b, the gain difference is within ±7 dB over the entire domestic reception frequency band, as shown in Fig. 6c. Therefore, the antenna element 10c can be used as a diversity antenna for domestic FM radio broadcasts, with better reception performance than the antenna element 10b.

[0057] Figure 7a shows an antenna element 10d in which the distance d between the horizontal conductor 14 (first horizontal conductor 14a) located on the Y1 side and the window frame 7a is set to +17 mm, and the antenna element 10d has a horizontal conductor 14 (second horizontal conductor 14b) connected to the busbar 2d on the Y2 side of the busbars 2d that supply power to the heating wires in the defog area 2c located outside the defog area 2c. Figure 7b shows the gain difference when the antenna element 10d is used. The second horizontal conductor 14b in Figure 7a extends downward from the busbar 2d on the Y2 side and extends in the Y direction toward the center of the rear window 2 (Y1 side) at a position where the distance d between the second horizontal conductor 14b and the window frame 7a is -8 mm. The second horizontal conductor 14b is then folded back 180 degrees near the center of the rear window 2 and extends toward the Y2 side. This folded portion is separated from the window frame 7a by a distance d of +7 mm, and extends from the Y2 side end of the rear window 2 to a position inward by about one-third of the left-right length of the rear window 2.

[0058] In the antenna element 10d shown in Fig. 7a, the gain difference is within ±5 dB over the entire domestic reception frequency band, as shown in Fig. 7b. Therefore, the antenna element 10d can be used as an optimal diversity antenna for domestic FM radio broadcasts, with better reception performance than the antenna elements 10b and 10c.

[0059] FIG. 8a shows an antenna element 10e having a horizontal conductor 14 (first horizontal conductor 14a) arranged on the Y1 side, with a separation distance d between the window frame 7a and the horizontal conductor 14 (second horizontal conductor 14b) set to +8 mm, and a horizontal conductor 14 connected to the busbar 2d on the Y2 side of the busbars 2d arranged outside the defog region 2c. FIG. 8b shows the gain difference when the antenna element 10e is used. The second horizontal conductor 14b in FIG. 8a extends downward from the busbar 2d on the Y2 side and extends in the Y direction toward the center of the rear window 2 (Y1 side) at a position where the separation distance d between the horizontal conductor 14 and the window frame 7a is −7 mm. This configuration is adjusted to reduce the gain difference in the overseas reception frequency band of 88 MHz to 108 MHz.

[0060] In the antenna element 10e shown in Fig. 8a, the gain difference is within ±5 dB over the entire overseas receiving frequency band, as shown in Fig. 8b. Therefore, the antenna element 10e can be used as an optimal diversity antenna for overseas FM radio broadcasts.

[0061] [Other Embodiments] Next, the configuration of the antenna and the like including the glass antenna A for a vehicle according to other embodiments of the present invention will be described. In this embodiment, the configuration of the antenna and the like is different from that of the above embodiment. Other configurations are the same as those of the above embodiment. Therefore, in the description of this embodiment, parts having the same configuration as those of the above embodiment are given the same reference numerals, and detailed description of the same configurations will be omitted.

[0062] (1) In the above embodiment, the shark fin antenna 20 is used as one of the antennas constituting the phase diversity type diversity antenna, but this is not limited to this. For example, an antenna of any shape can be used at any location on the electric vehicle 1, such as a rod antenna, an antenna built into the rear spoiler, or an antenna built into the rear wing, as long as it can form a diversity antenna with the vehicle glass antenna A. However, it is preferable to place the antenna in a position where electromagnetic noise generated inside the electric vehicle 1 (particularly the DC-DC converter 5) is blocked by the metal exterior panel 7.

[0063] (2) In the above embodiment, the horizontal conductor 14 of the antenna element 10 extends along the X direction, but it may be configured to extend at an angle relative to the X direction. In this case, the horizontal conductor 14 may be configured to intersect with the window frame 7 a of the metal exterior panel 7 when the electric vehicle 1 is viewed from the rear to the front.

[0064] (3) In the above embodiment, the antenna element 10 is disposed below the rear window 2 in the X direction (X2 side). However, it may be configured to be disposed above the rear window 2 (X1 side).

[0065] The present invention can be used for a glass antenna for a vehicle.

[0066] 1: Electric vehicle 2: Rear glass (glass plate) 2a: Inner surface (plate surface) 2b: Outer edge 3: Motor 4: Battery 5: DC-DC converter (transformer) 6: On-board electronic device (equipment) 7: Metal exterior panel (shielding portion, metal plate) 7a: Window frame (opening edge) 7b: Internal area (opening area) 7c: Roof (shielding portion, metal plate) 10: Antenna element (first antenna element) 10a: Antenna element (first antenna element) 10b: Antenna element (first antenna element) 10c: Antenna element (first antenna element) 14: Horizontal conductor (horizontal element) 14a: First horizontal conductor (horizontal element) 14b: Second horizontal conductor (horizontal element) 14c: Third horizontal conductor (horizontal element) 20: Shark fin antenna (second antenna element) 22 : Power supply unit 24 : Antenna unit (element) A : Vehicle glass antenna

Claims

1. A glass antenna for vehicles installed on an electric vehicle that can run by the driving force of a motor powered by a battery, comprising: a glass plate that separates the inside and outside of the electric vehicle; and a first antenna element that is fixed to the plate surface of the glass plate and is capable of receiving radio waves propagating through the air outside the electric vehicle, wherein the first antenna element is installed outside the electric vehicle via a blocking section that can block electromagnetic noise emitted from a transformer located between the battery and a device powered by the battery, and cooperates with a second antenna element that can receive the radio waves to form a diversity antenna.

2. A glass antenna for vehicles as claimed in claim 1, wherein the blocking portion is made of a metal plate.

3. The vehicle glass antenna according to claim 2, wherein the blocking portion is a metal exterior panel of the electric vehicle.

4. The vehicle glass antenna according to any one of claims 1 to 3, wherein the diversity antenna is used in a phase diversity receiving system.

5. A glass antenna for vehicles according to any one of claims 1 to 4, wherein the radio waves include a frequency band used for FM radio broadcasting.

6. A glass antenna for vehicles as claimed in any one of claims 1 to 5, wherein the second antenna element has a power supply portion and an element, and is arranged in the order of the power supply portion and the element in a direction away from the blocking portion.

7. A glass antenna for vehicles according to claim 3, wherein the first antenna element is disposed at a position capable of being capacitively coupled with the metal exterior panel.

8. The glass antenna for vehicles according to claim 7, wherein the first antenna element has a receiving gain equal to that of the second antenna element.

9. A glass antenna for vehicles as described in claim 8, wherein an outer edge of the glass plate is fixed so as to cover an opening area formed in the metal exterior panel of the electric vehicle, and the first antenna element includes a horizontal element arranged perpendicular to the opening edge of the opening area in the left-right direction of the electric vehicle and at a distance along the plate surface of the glass plate of 20 mm or less.

10. A glass antenna for vehicles according to claim 9, wherein the horizontal element is disposed closer to the center of the glass plate than the edge of the opening region.

11. The glass antenna for a vehicle according to claim 9, wherein the horizontal element is disposed on the outer edge side of the glass plate with respect to the opening edge of the opening region.

12. The glass antenna for vehicles according to claim 9, wherein the glass plate is a rear glass of the electric vehicle, and the blocking portion is a roof.

13. The glass antenna for a vehicle according to claim 12, wherein the first antenna element is disposed below the rear glass in the up-down direction.

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