JP2009111704A - Vehicular reception equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide vehicular reception equipment, which is less susceptible to electromagnetic noise and having a preferable directivity. <P>SOLUTION: The vehicular reception equipment 1 receives frequency modulation broadcast (FM broadcast) or the like. An antenna element 11 is arranged at the peripheral rim part of a metallic roof unit 21 of a vehicle 20. In this case, one end of a radial 12 is electrically connected so that the radial 12 comes to have a potential equal to the arranging place of the antenna element 11 of the roof unit 21. Further, the radial 12 is extended from the vicinity of the connecting place of the roof unit along the surface or the inner surface of a rear glass 30. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle receiving facility for providing a radio broadcast or the like in a vehicle.

  Most automobiles currently on the market are equipped with a receiver for receiving radio broadcasts and an antenna connected to the receiver for receiving radio broadcast waves. It is desired that a receiving facility (receiver and antenna) installed in an automobile satisfies different requirements from a stationary receiving facility and a portable receiver. One of the requirements is that it is difficult to receive electromagnetic noise in an automobile in which various electric devices are mounted and the installation location of the receiving facility is limited by various conditions. Another requirement is that even if the car changes its course (that is, even if the traveling direction of the car changes relative to the direction of arrival of radio waves), the influence of fading is small.

Conventionally, it is a “vehicle antenna structure” applied to a radio disposed substantially in the center in the vehicle width direction on the front side of a vehicle interior, and a monopole antenna that receives radio waves such as AM waves and FM waves is received by a radio (reception). Machine) and connecting the cables with the center cluster equipment, the body ECU and the electric motor, etc., which are located in the vicinity of the antenna and which may generate electric noise, are covered with a metal cover. Is grounded (grounded) on the vehicle body side via a harness such as a ground wire (see, for example, Patent Document 1).
JP 2002-36964 A (paragraphs [0014], [0018], FIG. 1)

  However, in the “vehicle antenna structure” (described in Patent Document 1), a device that may generate electrical noise is covered with a metal cover. For example, a power plant for a hybrid vehicle that is becoming common in recent years. It is difficult to sufficiently shield a number of devices (particularly electrical devices). For this reason, there has been a problem that radio receivers are easily affected by electromagnetic noise from the antenna. In addition, since this “vehicle antenna structure” is arranged on the front side of the vehicle interior, there is a problem that the received wave coming from the rear of the body is particularly attenuated, and the antenna directivity is biased forward.

  SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vehicle receiving facility that solves the above-described problems and has good directivity that is less susceptible to electromagnetic noise.

  In order to solve the above-mentioned problems, a receiving apparatus for a vehicle according to the present invention has one end so as to be equipotential with an antenna element disposed at a peripheral portion of a metal roof portion of the vehicle and an arrangement position of the antenna element of the roof portion. Are electrically connected and provided with a radial extending from the roof portion.

  According to the present invention, it is possible to provide a vehicular reception facility that is less susceptible to electromagnetic noise and has good directivity.

Next, the best mode for carrying out the present invention (hereinafter referred to as “embodiment”) will be described in detail with reference to the accompanying drawings.
FIG. 1A is a perspective view showing an appearance of a vehicle 20 provided with a vehicle receiving facility 1 according to the present invention (described later with reference to FIG. 4), and FIG. FIG. Referring to FIG. 1, an antenna element 11 and a radial 12 are main components of the vehicle receiving facility 1.

  The antenna element 11 is arranged in the vicinity of the rear end on the roof portion 21 of the vehicle 20, that is, in the vicinity of the rear glass 30 and in the vicinity of the center of the left and right in the traveling direction of the vehicle 20. In addition, the antenna element 11 can be arrange | positioned if it is not only the rear-end part of the roof part 21, but the peripheral part of a roof part. The antenna element 11 is grounded, and is grounded to the metal roof portion 21, and its electrical length (electric length) is λ / 4 that resonates well with the received wave of wavelength λ, It is preferable that the angle is 5λ / 8 at which a launch angle close to the horizontal direction can be obtained. The antenna element 11 is, for example, a micro antenna or a whip antenna used as a vehicle-mounted radio antenna.

  A radial 12 is arranged from the vicinity of the ground point of the antenna element 11 along the rear glass 30 toward the rear of the vehicle 20. The radial 12 is a conductor wire or a conductor film, and is, for example, a silver wire, a copper wire, or an aluminum wire covered with an insulating coating. The radial 12 may use a litz wire from the viewpoint of reducing the effective resistance value of the high-frequency current. One end of the radial 12 (near end with respect to the antenna element 11) is electrically connected to the ground point of the antenna element 11. One end of the radial 12 and the grounding point of the antenna element 11 may be connected directly or using a connection line (not shown), or via a metal portion (the roof portion 21 or the like) of the vehicle 20. May be connected. Although an example in which the other end of the radial 12 (far end with respect to the antenna element 11) is grounded to the vehicle 20 is illustrated, this end (far end) may not be grounded.

  That is, the extending direction of the radial 12 is a direction away from the roof portion 21 along the plane of the window glass from the ground point near the antenna element 11 on the roof portion 21. That is, when the antenna element 11 is disposed behind the peripheral edge of the roof portion 21, the radial 12 extends from the ground point on the roof portion 21 along the surface of the rear glass 30 to the rear of the vehicle 20 (see FIG. 1). It will be extended toward. In other words, at least a part of the radial 12 extends in parallel to a plane that divides the vehicle 20 into left and right.

  The electrical length (electric length) of the radial 12 is, for example, λ / 4 so as to resonate with the fundamental wave of the received wave with reference to the wavelength λ (in free space) of the received wave. In this case, the physical length (physical length) of the radial 12 is obtained by multiplying the electrical length (that is, λ / 4) by a predetermined wavelength shortening rate determined in consideration of the dielectric constant of the rear glass 30 and the like. Value. The electrical length of the radial 12 may be 5λ / 8. In this case, for example, the electrical length of the antenna element 11 may be 5λ / 8. Furthermore, when the electrical length of the radial 12 is λ / n (n is an integer of 1 to 20), good reception performance can be obtained. The reason why the length of the radial 12 is set to λ / n is that resonance occurs in one of the subharmonic wave, the fundamental wave, and the harmonic wave of the received wave, and n is set to 20 or less because the radial 12 has this length. This is because the radial 12 can be expected to exert a predetermined effect, and if the radial 12 is too short with respect to the wavelength λ of the received wave, the effect cannot be expected.

  The reference of the length of the radial 12 may be the length of the part where the radial 12 is extended on the rear glass 30. That is, the electrical length of the radial 12 on the rear glass 30 may be 5λ / 8, λ / 4, or λ / n (n is an integer of 1 to 20) as described above. This is because the radial 12 is extended from the vicinity of the antenna element 11 disposed at the rear end of the roof portion 21, and most of the radial 12 is extended on the rear glass 30. Further, in the radial 12, a portion extending on the rear glass 30 made of a dielectric operates more characteristically as a ground plane than on the roof portion 21 which is a metal member.

  A defogger 32 including a plurality of heat wires 31 is arranged on the rear glass 30 and is connected to the battery 27 via a switch 26 and a fuse (not shown).

FIG. 2 is a side view showing the appearance of the vehicles 20 and 20b in which the vehicle receiving equipment 1 according to the present invention (see FIG. 4) is installed. FIG. 2 (a) shows the case of a four-door vehicle, and FIG. b) shows the case of a 5-door car.
As shown in FIG. 2A, in the case of a vehicle 20 that is a four-door vehicle, the antenna element 11 is disposed in the vicinity of the rear end of the roof portion 21, and the rear glass 30 is connected to the ground point of the antenna element 11 or from the vicinity thereof. Accordingly, the antenna 10 can be configured by extending the radial 12 toward the rear of the vehicle 20.
As shown in FIG. 2B, in the case of a vehicle 20b that is a five-door vehicle, the antenna element 11 is disposed in the vicinity of the rear end of the roof portion 21, as in the case of the vehicle 20 that is a four-door vehicle. The antenna 10 can be configured by extending the radial 12 toward the rear of the vehicle 20 along the rear glass 30 from or near the grounding point of the element 11.

As shown in FIGS. 2A and 2B, the vehicles 20 and 20b are hybrid vehicles or electric vehicles, and include a vehicle interior power plant 25 below the vehicle interior rear portion. Since the antenna element 11 is located on the roof portion 21 above the rear portion of the vehicle interior, the antenna element 11 is relatively susceptible to electromagnetic noise from devices arranged at the rear rear portion of the vehicle interior such as the vehicle interior power plant 25. The configuration of the present embodiment effectively suppresses the influence of the electromagnetic noise.
In addition, since the roof portion 21 occupies the highest ground height position in the vehicle 20, the installation height of the antenna element 11 disposed on the roof portion 21 is also high, and particularly in the frequency band of ultra high frequency or higher, the received signal The strength of can be increased.
Furthermore, by arranging the antenna element 11 at the rear end portion of the roof portion 21, it is possible to give a elegant impression to the vehicles 20 and 20b and to improve the design.

FIG. 3 is a longitudinal sectional view showing a surface obtained by cutting the rear glass 30 along the radial 12. In each of the drawings shown in FIGS. 3A to 3D, the upper side along the plane of the paper is the vehicle interior side, and the lower side along the plane of the paper is the vehicle interior side.
The heat ray 31 which comprises the defogger 32 (refer FIG. 1) is arrange | positioned in the vehicle interior side surface of the rear glass 30 shown to Fig.3 (a) to FIG.3 (d) all.

  As shown in FIG. 3A, in the first example of the radial 12 arrangement, the radial 12 is extended along the vehicle outer side surface of the rear glass 30. The heat wire 31 (1) generates heat when energized with a direct current, and has a relatively large impedance not only with respect to direct current but also with respect to a high frequency current, and (2) radial due to the rear glass 30 that is a dielectric. 12 are separated from each other, and (3) the extending direction of the radial 12 (the longitudinal direction of the vehicle 20) and the extending direction of the hot wire 31 (the lateral direction of the vehicle 20) are substantially perpendicular to each other. Does not significantly affect the radial 12 as a conductor.

  As shown in FIG. 3B, in the second example of the radial 12 arrangement, the radial 12 is formed by being embedded in the rear glass 30. In this example as well, the same effect as in the first example can be obtained, but for the effect based on the reason (2), the radial 12 is embedded so that the radial 12 is closer to the outside of the rear glass 30.

  As shown in FIG. 3C, in the third example of the radial 12 arrangement, the radial 12 extends along the vehicle interior side surface of the rear glass 30, and insulates the radial 12 from the heat wire 31. An insulating member 33 is interposed therebetween.

  As shown in FIG. 3D, in the fourth example of the radial 18 arrangement, the radial 18 formed by covering the core wire 18a made of a high-frequency good conductor with a coating 18b made of an insulator is formed on the inner surface of the rear glass 30 in the vehicle ( That is, it extends over the hot wire 31.

FIG. 4 is an explanatory diagram schematically showing the vehicle receiving facility 1 according to the present invention.
The vehicle receiving facility 1 includes an antenna 10 having an antenna element 11 and a radial 12, a coaxial cable 15 having an inner conductor (core wire) 14 and an outer conductor (mesh wire) 13, and a receiver 16. It consists of
The antenna element 11 may include a preamplifier 17 that is a small-signal high-frequency amplifier that amplifies a reception signal having a target frequency immediately below the main body.

  The output signal from the preamplifier 17 is guided to the receiver 16 by the coaxial cable 15. One end (upper end) of the outer conductor 13 of the coaxial cable 15 is electrically connected to the roof portion 21 together with the ground side of the output terminal of the antenna element 11. Since the radial 12 is also grounded at or near this connection point, the ground point of the antenna element 11, the upper end of the coaxial cable 15, and the antenna element 11 side of the radial 12 operate at substantially the same potential during reception. . Therefore, the roof portion 21 operates as a ground plane in front of the antenna element 11, and the radial 12 operates as a ground plane in the rear of the antenna element 11. Thus, since the antenna 10 is substantially non-directional in a horizontal plane, it is possible to suppress the influence of fading due to the change of the vehicle 20 (see FIG. 1 and the like).

  At the other end (lower end) of the coaxial cable 15, the inner conductor 14 is connected to a circuit inside the receiver 16, and the outer conductor 13 is connected to the housing of the receiver 16. The housing of the receiver 16 is made of metal, and is grounded in the passenger compartment of the vehicle 20 (see FIG. 1 and the like). Thus, the ground side of the antenna element 11, the antenna element 11 side of the radial 12, the rear end portion of the roof portion 21, the outer conductor 13 of the coaxial cable 15, and the housing of the receiver 16 are connected to each other, and the roof portion. 21 and the vehicle interior of the vehicle 20 are grounded, the reception signal from the antenna element 11 is suppressed from being mixed with electromagnetic noise from the vehicle interior power plant 25 (see FIG. 2) and the like. To reach.

  The receiver 16 typically receives an ultra-short wave broadcast (so-called FM radio broadcast), but is a medium-wave broadcast (so-called AM radio broadcast), a television broadcast, a text multiplex broadcast, an audio multiplex broadcast, and a data multiplex. It may have a receiving function such as broadcasting. In these cases, in addition to the antenna element 11, an element suitable for the frequency of the broadcast wave to be received is provided.

  FIG. 5A is a rear view showing a state in which a five-door vehicle 20c provided with the radial 12 of the first modification is viewed from the rear, and FIG. 5B shows the radial 12 of the second modification. FIG. 5C is a rear view showing a state in which the 5-door vehicle 20d provided is viewed from the rear, and FIG. 5C shows a state in which the 5-door vehicle 20e provided with the radial 12 of the third modification is viewed from the rear. FIG. 5D is a rear view showing a state in which the 5-door vehicle 20f of the comparative example is viewed from the rear. For convenience of explanation, the rear door is shown open.

  As shown in FIG. 5 (a), the radial 12 of the first modified example extends from the connection point G with the roof portion 21 (see FIG. 1 and the like) to the right side in the traveling direction (right side of the page) in the vehicle 20c. The vehicle is bent near the right end of the vehicle 20c and returned to the vicinity of the connection point G, bent substantially at a right angle, and extends rearward of the vehicle 20c along the rear glass 30. Although not shown, the radial 12 extends from the connection point G with the roof portion 21 (see FIG. 1 and the like) in the vehicle 20c to the left in the traveling direction (leftward in the drawing) and is bent near the left end of the vehicle 20c. It may return to the vicinity of the connection point G, bend at a substantially right angle, and extend rearward of the vehicle 20 c along the rear glass 30. As described above, the radial 12 may have a bent or curved shape as well as linearly extending.

  As shown in FIG. 5 (b), the radial 12 of the second modification has one end connected to the vehicle upper portion of the vehicle 20d or the vicinity of the right end in the traveling direction at the rear edge of the roof portion 21 (see FIG. 1 etc.). It extends to the left in the traveling direction (leftward in the drawing), bends at a substantially right angle near the center in the left-right direction, and extends rearward of the vehicle 20d along the rear glass 30. Although not shown, in the vehicle 20d, one end of the radial 12 is connected to the vehicle upper portion of the vehicle 20d or the vicinity of the left end in the traveling direction at the rear edge of the roof portion 21 (see FIG. 1 and the like), and to the right in the traveling direction (rightward in the drawing) It may be stretched, bent substantially at a right angle in the vicinity of the center in the left-right direction, and stretched rearward of the vehicle 20d along the rear glass 30.

  As shown in FIG. 5 (c), the radial 12 of the third modification electrically connects the roof portion 21 (see FIG. 1 and the like) and the rear door at the right end (right side of the paper) in the traveling direction of the vehicle 20e. The bonding wire 12a to be connected and the rear door of the closed state, the upper end of the bonding wire 12a is connected to the vicinity of the center in the left-right direction of the upper portion of the rear door, and the radial 12 main body extends to the rear of the vehicle 20. Although not shown, the bonding wire 12a may electrically connect the roof portion 21 (see FIG. 1 and the like) and the rear door at the left end of the traveling direction (left side of the paper). That is, the bonding wire 12 a is electrically part of the radial 12.

As shown in FIGS. 5 (a) to 5 (c), it is the periphery of the rear door or roof portion 21 (see FIG. 1 and the like) (that is, the boundary between the rear door or roof portion 21 and the rear glass 30). A tangent line (not shown) relating to the peripheral edge or boundary is drawn at a location where the radial 12 crosses, in other words, at the boundary between the rear door or roof portion 21 and the rear glass 30 and in the vicinity of the antenna 10. A certain portion of the radial 12 may extend to the roof portion 21, the rear door, the rear glass 30, etc. of the vehicles 20 c to 20 e so as to be parallel to the tangent line. Another part may be extended to the roof portion 21, the rear door, the rear glass 30 and the like of the vehicles 20c to 20e so as to be perpendicular to the tangent line.
As shown in FIG. 5 (d), the vehicle 20 f of the comparative example does not have the radial 12.

FIG. 6 (a) is a graph showing the reception characteristics of the vehicle 20c of the present embodiment shown in FIG. 5 (a) in terms of noise level with respect to frequency, and FIG. 6 (b) is a comparative example shown in FIG. 5 (b). It is a graph which shows the receiving characteristic in the vehicle 20d of this by the noise level with respect to a frequency.
As shown in FIG. 6A, in the vehicle 20c of the present embodiment, the noise level with respect to the noise floor (dark noise) is 5 in most frequency ranges from 87.5 MHz to 108.5 MHz. It is within [dBμV], and it can be seen that the influence of the noise source in the passenger compartment is very small.
As shown in FIG. 6B, in the vehicle 20d of the comparative example, the magnitude of the noise level based on the noise floor (dark noise) is 5 [ dB [mu] V] or more and 10 [dB [mu] V] or less, and it can be seen that it is influenced by a noise source in the passenger compartment.

  FIG. 7 shows a noise source installed in the vehicle interior power plant 25 (see FIG. 2) of the vehicle 20 of the present embodiment, and the spatial electric field strength with respect to the reception frequency at the apex position of the antenna element 11 for each thickness of the radial 12. It is a graph which shows the result of having simulated.

As shown in the figure, when there is no radial 12, the electric field strength of noise increases little by little as the frequency increases.
On the other hand, when the radial 12 is present, the electric field strength of noise is significantly lower than that without the radial 12 in a frequency band of approximately 85 MHz or higher. That is, it can be seen that providing the radial 12 has an effect of reducing noise.

Further, when the linear radial 12 having a diameter of 0.5 mm is provided, the electric field intensity of noise is lowest in the vicinity of 89 MHz. Further, when the linear radial 12 having a diameter of 1.0 mm is provided, the electric field intensity of noise is flat and low in a frequency band of 85 MHz or higher. In addition, when the linear radial 12 mm is provided, the electric field strength of noise is flat and low in the frequency band of 85 MHz or higher as in the case of the linear 1.0 mm radial 12. However, the electric field intensity of noise is the lowest in the vicinity of 79 MHz.
Thus, by changing the diameter (thickness) of the radial 12, it is possible to select a frequency band that is effective in reducing noise.

(A) is a perspective view which shows the external appearance of the vehicle which installed the receiver for vehicles by this invention, (b) is the perspective view which expands and shows the principal part typically. It is a side view which shows the external appearance of the vehicle which installed the receiving apparatus for vehicles by this invention, (a) shows the case of a 4-door vehicle, (b) shows the case of a 5-door vehicle. It is a longitudinal cross-sectional view which shows the surface which cut | disconnected the rear glass along radial. It is explanatory drawing which shows typically the receiver for vehicles by this invention. (A) is a rear view which shows the state which looked at the 5-door vehicle provided with the radial of the 1st modification from the rear, and (b) is the 5-door vehicle provided with the radial of the 2nd modification. It is a rear view which shows the state seen from the rear part, (c) is a rear view which shows the state which looked at the 5-door vehicle provided with the radial of the 3rd modification from the rear part, (d) is a comparative example It is a rear view which shows the state which looked at the vehicle of these 5 doors from the rear part. (A) is a graph which shows the receiving characteristic in the vehicle of this embodiment shown to Fig.5 (a) by the noise level with respect to a frequency, (b) is the receiving characteristic in the vehicle of the comparative example shown in FIG.5 (b). Is a graph showing the noise level with respect to frequency. It is a graph which shows the result of having simulated the spatial electric field strength with respect to the receiving frequency in the vertex position of an antenna element for every radial thickness by installing a noise source in the vehicle interior power plant of the vehicle of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Receiving equipment for vehicles 10 Antenna 11 Antenna element 12 Radial 15 Coaxial cable 16 Receiver 17 Preamplifier 20, 20b, 20c, 20d Vehicle 21 Roof part 25 Car interior power plant 30 Rear glass 31 Heat wire 32 Defogger

Claims (13)

An antenna element disposed at the periphery of the metal roof of the vehicle;
One end is electrically connected so as to be equipotential with the arrangement position of the antenna element of the roof portion, and a radial extending from the roof portion,
A receiver to which a signal received by the antenna element is input;
A vehicle receiving facility comprising:   2. The vehicle receiving equipment according to claim 1, wherein the radial electrical length is approximately λ / n (n is an integer of 1 or more and 20 or less), where λ is a wavelength of a reception wave.   2. The vehicular receiving facility according to claim 1, wherein the radial electrical length is approximately 5λ / 8, where λ is a wavelength of a received wave.   The electrical length of the radial portion of the vehicle that extends to the glass portion is approximately λ / n (where n is an integer of 1 to 20), where λ is the wavelength of the received wave. The vehicle receiving facility according to claim 1.   2. The vehicle receiving equipment according to claim 1, wherein an electrical length of a portion of the radial extending to the glass portion of the vehicle is approximately 5λ / 8 when a wavelength of a received wave is λ. .   The reception facility for a vehicle, wherein the reception wave is of an ultra high frequency FM broadcast.   The at least part of the radial is extended substantially perpendicularly to the peripheral edge or a tangent thereof at a position where the radial of the metal part of the vehicle crosses the radial. Vehicle receiving equipment according to any one of the above.   The vehicle receiving facility according to any one of claims 1 to 7, wherein at least a part of the radial is parallel to a plane dividing the vehicle into left and right.   The vehicle receiving facility according to claim 1, wherein at least a part of the radial is curved or bent.   The vehicle receiving facility according to any one of claims 1 to 9, wherein the radial is disposed on a glass surface of the vehicle.   The vehicle receiving facility according to any one of claims 1 to 9, wherein the radial is disposed inside a glass of the vehicle.   The vehicle according to claim 10 or 11, wherein the radial includes a curved or bent portion between a position of the roof portion where the antenna is disposed and a portion disposed on the glass. For receiving equipment. The vehicle is a hybrid vehicle or an electric vehicle equipped with a power control device at a rear part thereof,
The glass is a rear glass,
The vehicle receiving facility according to any one of claims 10 to 12, wherein

Images