JPS623507A - Antenna system for automobile - Google Patents

Abstract

PURPOSE:To attain the detection with high density, less noise and high quality to a broadcast wave by using a high frequency surface current generated in a rear roof and front pillar circumferential ridge so as to form a diversity broadcast wave reception antenna. CONSTITUTION:The 1st high frequency pickup 32 is arranged closely along a rear circumferential ridge at the right side of a rear roof 34 in the lengthwise direction of the front pillar at the right side. Then the 1st high frequency pickup 34 provided to the rear rood 34 of the car body and the 2nd high frequency pickup 36 provided to the front pillar constitute a space diversity reception antenna system whose directivities are compensated together and an antenna having the better reception sensitivity is selected always automatically. Thus, the directivities are compensated together and excellent reception of FM waves is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field 1] The present invention is an antenna device for an automobile, particularly an antenna device for effectively detecting broadcast waves received on the body of an automobile and supplying a detection signal to various receivers mounted on the automobile. The present invention relates to an improved antenna device for automobiles.

[Prior Art] An antenna device is indispensable for a car in order to ensure that a receiver installed in the car receives various broadcast waves such as radio, television, telephone broadcast communication waves, etc. This type of antenna device is extremely important for communicating with other stations, such as transmitting and receiving citizen band radio waves.
It will play a major role in the standard communication functions of future vehicles.

A conventional general antenna device is known as a ball antenna, and although the antenna protruding from the car body shows favorable performance in terms of reception characteristics, it has the fate of always being treated as a nuisance when it comes to the car body. had.

In addition, such ball antennas are prone to breakage, bending, and other damage even in actual use, are subject to mischief or theft, and also cause various problems such as generating unpleasant wind noise when driving at high speeds. Conventionally, there have been many requests to somehow remove this.

In particular, as the frequency bands of broadcast waves or communication waves received inside automobiles have expanded in recent years, it has become necessary to install multiple antennas for each frequency band, which has made it difficult to improve the aesthetic concept of the automobile's exterior. There is a problem in that the receiving performance of these antennas is significantly degraded due to mutual electrical interference between these various antennas.

In the past, several efforts have been made to remove or hide the above-mentioned ball antenna so that it cannot be seen from the outside, and for example, pasting an antenna m-line on the rear windshield has been put into practical use.

As another conventional solution, it has been proposed to detect surface current induced in the vehicle body itself by broadcast waves. At first glance, utilizing the current flowing through the car body seems to be the most reliable and efficient method, but previous experiments have continued to show results that completely contradict these expectations.

The first reason why it was not possible to use the surface current generated by general car body broadcast waves is that the surface current value was not as large as expected, and the conventional surface current mainly targeted the front roof of the car body. Even with this, it was not possible to obtain a detection output of a level sufficient for full use.

The second problem with the conventional method is that a very large proportion of noise mixes into the surface current, and this noise mainly comes from the engine's ignition system and battery charging regulator system, and when the engine is active. As a result, these noises leaked into the vehicle body, making it impossible to receive clear broadcast waves that could be used for practical purposes.

Even under such disadvantageous conditions, several proposals have been made in the past. Japanese Patent Publication No. 53-22 as a conventional antenna device that utilizes the current induced in the car body by broadcast waves.
418 is known, in which an electrical insulator is formed in a current concentration area of the vehicle body, and the current across the insulator is directly detected by a sensor. It is certainly suggested that this conventional device can obtain a practically usable detection signal with an excellent S/N ratio, but its pickup structure requires a cutout in a part of the vehicle body, etc. It was impossible to apply this method to mass-produced automobiles.

Another conventional device is known from Japanese Utility Model Publication No. 53-34826, which proposes an antenna that uses a pickup coil to detect the current flowing through the pillar of a vehicle. Although this conventional device was useful in showing the direction of development in which the antenna is built into the vehicle body, it is actually impractical to provide a pickup coil near the pillar and perpendicular to the longitudinal direction of the pillar. Furthermore, it was not possible to obtain a practical antenna output with such a pickup arrangement, and it was considered to be nothing more than an idea.

[Problems to be Solved by the Invention] Problems of the Prior Art As described above, antenna devices for detecting current induced in a vehicle body by broadcast waves have not necessarily been successful in the past.

In particular, in the past, the pickup structure for effectively detecting the current flowing through the vehicle body and the pickup arrangement for obtaining a practical S/N ratio, which are the main problems mentioned above, have not been properly solved. In fact, various experimental results indicated that antenna devices using car body current may not be usable in principle.

1. Standing Road The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to effectively detect the current induced in the vehicle body by broadcast waves and transmit it to the receiver mounted on the vehicle. An object of the present invention is to provide an improved antenna device for a small automobile that is capable of providing the following functions.

[Means for solving the problem] Conventional antenna devices were mainly intended to receive AM waves due to the background of the times. The result is that good reception characteristics cannot be obtained because the wavelength of
By setting the frequency above the M frequency band to 50 Hz or above, it has become possible to receive signals from the vehicle body current extremely effectively, which was previously considered impossible.

In addition, in the present invention, we have focused on the fact that the current value of such high-frequency car body current has a distribution characteristic that is significantly different in each part of the car body, and we have focused on the fact that the current value of such high-frequency car body current has a distribution characteristic that is significantly different in each part of the car body. The present invention is characterized by the provision of a high frequency pickup, and the rear roof and front pillar of the vehicle body are selected as installation locations that satisfy these conditions.

That is, in the present invention, in order to reliably detect the high-frequency current having the above-mentioned frequency characteristics, the first high-frequency pickup is disposed close to the right or left rear edge of the rear roof of the automobile along its longitudinal direction. , and the second high frequency pickup is connected to the first high frequency pickup.
A spatial diversity system is adopted in which the first and second high-frequency pickups are disposed close to the front pillar of the automobile along the longitudinal direction thereof, and the reception signals of the first and second high-frequency pickups are switched and used. It is.

Here, the first high frequency pickup and the second
When a high-frequency pickup is placed on the right side of the vehicle, the FMm region directional characteristic of the first high-frequency pickup exhibits strong sensitivity toward the right side of the vehicle and in the longitudinal direction.
The high-frequency pickup exhibits strong sensitivity in the left and right directions of the vehicle.

In addition, when the first high frequency pickup and the second high frequency pickup are installed on the left side of the vehicle body, the first high frequency pickup
The second high-frequency pickup exhibits strong sensitivity in the left and front-back directions, and the second high-frequency pickup exhibits strong sensitivity in the left-right direction.

In this way, the FM band directivity characteristics of the two high-frequency pickups complement each other's weaker sensitivity directions, and since both pickups are installed spatially apart from each other, By switching and using the reception signals of these high frequency pickups, it is possible to obtain a good spatial diversity effect.

Each of the high-frequency pickups may be of a loop antenna type for electromagnetically detecting the magnetic flux generated by the car body current, or an electrode that can electrostatically detect high-frequency signals by forming a capacitance with the car body. These types provide an efficient detection effect.

[Embodiment 1] Hereinafter, a preferred embodiment of the automotive antenna device according to the present invention will be described with reference to the drawings.

Installation position of high frequency pickup Figures 4 to 9 explain the process for determining the most efficient antenna installation position by examining the distribution characteristics of high frequency current.

FIG. 4 shows that when an external radio wave W such as a broadcast wave passes through a car body B made of a metal conductor, a surface current I corresponding to the strength of the electromagnetic wave is induced in each part of the car body. Of these radio waves, 50M+! belongs to a relatively high frequency band! , Z and above, only frequency bands used for FM waves, television waves, etc. are targeted.

The present invention is characterized in that the induced current distribution of the vehicle body is measured in such a specific high frequency band, and the pickup is installed in a portion where the surface current density is high and there is little noise.

In order to know the surface current distribution, computer simulations and actual current intensity measurements are performed at each point, and in the present invention, a probe based on the same principle as a high frequency pickup installed at a desired vehicle body part, which will be described later, is used. The surface current was measured by moving this probe over the entire surface of the vehicle body, changing the direction at each point from time t5.

Figure 5 shows the schematic structure of the probe P, which was created based on almost the same principle as the high-frequency pickup described later, and is made of a conductor to avoid mixing in radio waves from the outside. A loop coil 12 is fixed inside a case 10, and a part of the case 10 has an opening 10a.
is provided, and a part of the loop coil 12 is connected to this frontage 10a.
The loop coil 12 is exposed to the outside, and the exposed portion of the loop coil 12 is brought close to the surface of the vehicle body B, so that the loop coil 12 detects the magnetic flux generated from the vehicle body surface current.

A part of the loop coil 12 is connected to the case 1 by the shorting wire 14.
0, and the output end 16 is connected to the coaxial cable 1.
8 core wires 20. Also, the loop coil 12
A capacitor 22 is provided in a part of the loop coil 12 to resonate the frequency of the loop coil 12 to a desired frequency to be measured, thereby increasing pickup efficiency.

As described above, by moving the probe P along the surface of the vehicle body B and rotating its angle at each measurement point, it is possible to accurately determine the surface current distribution and its direction on the vehicle body surface. In FIG. 5, the output of the probe P is amplified by a high frequency voltage measuring device 24, and the output voltage is measured by a high frequency voltage measuring device 26. This coil output voltage is read by the meter indication value of the measuring device 26, and the voltage corresponding to this meter indication value is recorded by the XY recorder 28 as a surface current distribution in each part of the vehicle body. A signal indicating each position of the insect body is inputted to the XY recorder 28 from a potentiometer 30, making it possible to know the high frequency surface current at each position.

FIG. 6 shows the deviation angle θ between the high-frequency surface current ■ and the loop coil 12 of the pickup, and as shown in the figure, the magnetic flux φ caused by the current I is detected by the loop coil 12 by interlinking with the loop coil 12. Avoid generating a voltage V, and as shown in Figure 7, the maximum voltage is obtained when θ is O, that is, the surface type ff, tI is parallel to the loop coil 12 of the pickup, and the probe P is rotated at each measurement point. The direction of the surface current I when the maximum voltage is obtained can be known.

Figures 8 and 9 show the magnitude and direction of the high-frequency surface current generated in each part of the vehicle body at a frequency of 80H1lz, which was determined from both the measurement results using the probe P and the computer simulation. As is clear from the above, the magnitude of the surface current exhibits a distribution in which the density is high along the edges of the flat plate portion of the vehicle body, and the density is extremely low in the central portion of the flat plate portion.

Furthermore, as shown in the direction of the current in FIG. 9, it is understood that each current is concentrated in a direction parallel to the edge portion of the vehicle body or along a connection portion of each plane portion.

In Fig. 8, if we examine in detail the current distribution induced in the aforementioned metal parts of the car body along the chain line that traverses the car body, we find that
The distribution characteristics as shown in FIGS. 10 to 12 are (q).

Figure 10 shows the surface current distribution along the trunk lid from the vertical new line △ to 8. As is clear from the figure, the largest current flows at both ends, and from these ends to the center of the lid. It shows a distribution characteristic in which the current value decreases towards the end.

Also, Fig. 11 shows the current distribution along the roof of the car body, and Fig. 12 shows the current distribution along the engine cover of the car body. 1 current distribution is shown, and when this current distribution is compared with the magnitude and direction of the high-frequency surface current shown in FIGS. 8 and 9, it is found that It is understood that the high-frequency current flows in a concentrated manner in parallel directions, and the current value decreases toward the center.

Furthermore, such high-frequency surface currents can be applied to the connecting parts of each plane part of the vehicle body, such as the pillars that support the ceiling panel.

The flow also concentrates along the trunk hinge etc., for example, FM
In the frequency band, a high-density surface current that is equal to or higher than the other parts flows in the pillar part, and this tendency becomes more pronounced as the frequency increases, and in the conventional AM band, it is practically possible to obtain the antenna output. This makes it possible to detect current from part of the pillar, which was previously not possible.

Therefore, in the present invention, by arranging the high frequency pickup near the peripheral edge of each part of the car body or along the connecting part of the flat part, it is possible to detect the high frequency current flowing in each part of the car body and pick up broadcast waves with good sensitivity. That is understood.

In the present invention, the high-frequency pickup is installed close to the peripheral edge of each vehicle body, for example, by arranging a loop antenna in the longitudinal direction along the peripheral edge. It is preferable to set the pickup installation range from the station to a range that depends on the carrier frequency of the broadcast wave.

The distribution characteristics shown in Figures 10 to 12 are the car body current for the FM broadcast frequency of 80HIIz, and as mentioned above, the surface current value decreases as the distance from each car body end or edge increases, indicating that the sensitivity is actually good. 6dB that can be obtained
1 below! Considering the flow reduction range, it is understood that extremely good sensitivity can be obtained within 4.5 CI1 from the edge in each characteristic.

Therefore, in the present invention, for a carrier frequency of 80 Hllz, the high frequency pickup is placed at a distance of 4.56 mm from the periphery of the vehicle body.
(2) If the antenna device is placed within the range 2, a practically sufficient antenna device can be obtained.

It has become clear from computer simulation results and various experimental results that this practical separation distance depends on the carrier frequency, and it has been recognized that the practical separation distance decreases as the frequency increases.

Therefore, since the above-mentioned practical separation distance of 4.5C11 at the carrier frequency of 80MHz is inversely proportional to the frequency, in the present invention, the four ranges of ilQ of the high frequency pickup from the flat metal edge of the vehicle body are set to 12x 10-
If it is provided within 3 c# (m), a good reception effect can be obtained depending on each carrier frequency (in the above equation, C - speed of light, f =
carrier frequency).

As described above, according to the present invention, the high frequency pickup is provided close to the edge of each metal car body, and preferably within the above-mentioned distance from the edge, thereby obtaining a good receiving effect. .

In the present invention, in practice the separation distance is frequency dependent, so for example at carrier frequency 1008H2,
It is sufficient to install the high-frequency pickup within 3.6 cm from the edge of the vehicle body, and as the carrier frequency r increases, the installation location of the high-frequency pickup is limited to a narrow area close to the edge. becomes.

It should be noted that since the above-mentioned connecting parts of the flat plate parts, such as pillars or trunk hinges, have narrow widths, there is almost no need to consider the above-mentioned separation distance, and the high frequency pickup can simply be placed close to the connecting parts along the longitudinal direction. , it becomes possible to pick up broadcast waves with good sensitivity.

By the way, when high frequency pickups are arranged close to each other near the peripheral edge of each part of the vehicle body to receive broadcast waves, the directivity characteristics of each high frequency pickup as an antenna are different from each other.

The characteristic feature of the present invention is that it employs a diversity reception method by combining such high-frequency pickups with different directional characteristics, making it possible to always receive broadcast waves in good reception conditions. , in the present invention,
A first high-frequency pickup disposed close to the right or left rear edge of the rear roof of the vehicle along its longitudinal direction; and a second high frequency pickup disposed close to each other along the antenna, and the first and second high frequency pickups are used to form a diversity type automobile antenna device.

A preferred embodiment of the antenna device of the present invention is shown in FIG. This is because the second high-frequency pickup 36 is disposed close to the peripheral edge along its longitudinal direction, and the second high-frequency pickup 36 is disposed close to the right front pillar 38 along its longitudinal direction.

FIG. 2 shows the FM of the first high frequency pickup 32.
Band directional characteristics are shown, and as is clear from the figure, it is understood that this first high frequency pickup 32 exhibits strong sensitivity in the right side and front and rear directions.

Further, FIG. 3 shows the second high frequency pickup 36.
FMWI region directivity characteristics are shown, and as is clear from the figure, it is understood that this second high frequency pickup 36 exhibits strong sensitivity in the left and right directions of the vehicle.

Therefore, by combining the first high-frequency pickup 32 and the second high-frequency pickup 36 and employing a diversity reception system, it is possible to mutually complement the directional characteristics and perform good FM wave reception.

Furthermore, the first ^ frequency pickup 32 and the second high frequency pickup 36 are arranged at an angle of approximately 1 in the longitudinal direction of the vehicle body.
．． They are installed at intervals of about 5 to 1.8 m, and FM
Since the wavelength of the wave is about 4.25 m, F M Wf
It is understood that the effect of spatial diversity in the area is extremely large.

In the embodiment shown in FIG. 1, the first high-frequency pickup 32 and the second high-frequency pickup 36 are installed on the right side of the vehicle body, but the present invention is not limited to this. It is also possible to similarly install both the pickups 32 and 36 on the left side of the vehicle body, and in this case, the first and second high frequency pickups 3
2 and 38 exhibit left and right directional characteristics that are completely opposite to the directional characteristics shown in FIGS. It is understood that this constitutes a good spatial diversity receiving antenna arrangement.

Next, based on FIG. 1, the first high frequency pickup 32
A circuit configuration for automatically selecting the one with better reception sensitivity between the first and second high-frequency pickups 36 to receive broadcast waves will be explained.

In FIG. 1, coaxial cables leading to the respective outputs of four high-frequency pickups 32 and 36 are input to a high-frequency amplification circuit 42 via a switch circuit 40.

Here, the switch circuit 40 is switched by the output from the T-type flip-flop 44, and by switching the switch circuit 40, either the output of the high frequency pickup 32 or 36 is selectively input to the high frequency amplifier circuit 42. The output of the received wave passes through an intermediate frequency amplification circuit 48 to which a local oscillation circuit 46 is connected, and then only the reputation signal is extracted by a wave circuit 50.

Thereafter, this audio signal is separated into a right output and a left output via a multiplexer 52, and left and right amplification tl154L
and 54R to left and right speakers 56L and 5, respectively.
It is played from 6R.

Incidentally, the output signal from the intermediate frequency amplification circuit 48 is compared with a threshold value of the signal in a comparator 58, and the comparator 58 is provided with a signal when the receiving sensitivity by the four high frequency pickups 32 and 36 falls below a predetermined value. The comparator 58 is set with a threshold value of the signal output from the intermediate frequency amplification circuit 48 for outputting a trigger output to invert the T-type flip-flop when the T-type flip-flop is inverted. and 36, the signal output from the intermediate frequency amplification circuit 48 is compared with the signal output from the intermediate frequency amplification circuit 48, and if the signal is below the threshold value, the T-side flip 70 knob 44
A trigger signal is sent to invert the output of the T-type flip 70 tube 44.

As a result of this output reversal, the switch circuit 40 is switched to either the high frequency pickup 32 or 36 with a better reception condition.

Therefore, the first high frequency pickup 32 provided on the real-734 of the vehicle and the second high frequency pickup 32 provided on the front pillar.
The high-frequency pickup 36 constitutes a spatial diversity receiving antenna device whose directional characteristics complement each other, and the antenna can always be automatically switched to an antenna with good receiving sensitivity.

First High Frequency Pickup Next, the specific configuration of the first high frequency pickup 32 provided at the periphery of the rear roof of the vehicle will be described in detail below.

13 to 15 show an embodiment of the present invention in which a high frequency pickup is disposed close to the rear edge of the rear roof.

In FIG. 13, the rear roof 34 is shown in an exposed state, and this metal roof 734 is connected to the rear glass 62 with the rear window frame 60 as its peripheral edge.

As shown in detail in FIG. 14, the high frequency pickup 32 includes a metal case 64 that seals magnetic flux from the outside, includes a loop antenna 66 inside the case 64, and has a T
It forms a magnetic coupling type pickup and has a configuration similar to the probe including the loop coil used to determine the surface current distribution of the vehicle body described above.

In Fig. 15, the high frequency pickup 32 is 7/1z.
-734, the rear roof 34 includes a rear panel 68 with the previously described rear window frame 60 secured to one end of the roof panel 68, and with the roof panel 68 having fasteners 70 and The rear glass 62 is fixed via a dam 72, and the fastener 70 and the dam 72 are airtightly attached using an adhesive 74. In addition, the roof panel 68 and the rear glass 6
A molding 76 is fixed between the two.

Furthermore, a roof garnish 88 is provided inside the rear window frame 60 (inside the vehicle body) in the Real-734.
is fixed to the roof panel 68, and an edge molding 90 is fixed to one end of the roof garnish 88 and the rear window frame 60.

An edge molding retainer 92 for mounting the edge molding 90 is arranged between the front wind frame 60 and the roof garnish 88. This retainer 92 is separated from the rear window frame 60 by spacers 94 and 96.

In this embodiment, in order to arrange the loop antenna 66 of the high-frequency pickup 32 to face the peripheral edge of the retainer 92, an opening 60a is first provided in a part of the front wind frame 60, and the high-frequency pickup 32 cases 64 are inserted and arranged.

That is, the characteristic feature of this embodiment is that the retainer 9
The loop antenna 66 of the high frequency pickup 32 is disposed near the peripheral edge of the high frequency pickup 32 along its longitudinal direction.

Since the length of the retainer 92 in the arm direction is approximately equal to about half a wavelength of the FM broadcast wave band, reception with even higher sensitivity can be achieved.

At this time, as shown in detail in FIG. 15, the case 64 of the high frequency pickup 32 is provided with an opening 64a through which the longitudinal side of the loop antenna 66 is exposed. case 64
The exposed portion of the loop antenna 66 is placed close to and opposite to the edge of the retainer 92 for edge mold attachment.

Therefore, the magnetic flux induced from the high frequency surface current flowing around the periphery of the retainer 92 inside the case 64 is reliably captured by the loop antenna 66.
The magnetic flux from the outside is reliably shielded, so
Sensitive high-frequency pickup 3 for current induced in the car body
2 enables detection.

In order to securely position and fix the case 64 of the high-frequency pickup 32 to the Edge Mall mounting retainer 92, L-shaped brackets 78 and 80 are connected to both ends of the case 64 with bolts or the like, as shown in FIG. The brackets 78 and 80 are fixed to the rear window frame 60 with screws.

Further, a circuit section 82 connected to the loop antenna 66 described above is built in the case 70 of the high frequency pickup 32, and a signal detected by a front amplifier or the like provided in the circuit section 82 is processed. Furthermore, the high frequency detection signal thus obtained is taken out from the coaxial cable 84 and processed by the same circuit as used in the surface current distribution measurement described above. The circuit section 82 is supplied with power and signals for circuit control from a cable 86.

The loop antenna 66 is a single-turn antenna, and the coil is coated with an insulating coating so as to be placed in close contact with the edge mold mounting retainer 92 while being electrically insulated, and is pressed against the end face of the retainer 92. This structure allows the magnetic flux generated from the surface current to more strongly intersect with the loop antenna 66.

In this embodiment, the side of the loop antenna 660 exposed from the case 64 is 4.5C1 from the edge of the retainer 92.
As a result, broadcast waves in the broadcast band frequency (particularly 50 to 300 HIIZ) can be reliably detected from the car body surface current flowing around the periphery of the retainer 92, and the direction of the car body surface current at this time is As is clear from FIG. 9, the flow is along the peripheral edge of the retainer 92, so in this embodiment, the loop antenna 66 is arranged with its longitudinal direction along the peripheral edge of the retainer 92.

Second High Frequency Pickup Next, the specific configuration of the second high frequency pickup 36, which is disposed close to the front pillar of the vehicle body along its longitudinal direction, will be described in detail below.

16 to 18 show the specific structure of the second high-frequency pickup 34 according to this embodiment. In the embodiment, this high-frequency pickup 36 is built in a front pillar 38 that supports a ceiling plate. Furthermore, this high frequency pickup 36 is an electromagnetic coupling type pickup including a loop antenna.

As is clear from the cross-sectional view of FIG. 17, 1. The front pillar 38 includes a pillar leg plate 136 formed in the shape of a hollow rectangular prism serving as its main pillar. A windshield molding 138 is fixed to the outer surface of the vehicle body of the pillar leg plate 136, and a windshield 140 is held on this molding 138.

Further, the pillar leg plate 136 is provided with weather protection on the rear side of the vehicle body.
A strip rubber 142 is fixed, and the rubber 142
This ensures watertightness between the side glass 144 and the side glass 144.

Further, a front pillar garnish 146 is attached to the pillar leg plate 136 on the passenger compartment surface side, and a front pillar garnish 146 is attached to the pillar leg plate 136.
It hides the surface and maintains its aesthetic appearance.

A characteristic feature of the present invention is that a high frequency pickup is disposed in the pillar, the front pillar 38 in the embodiment along the longitudinal direction of the pillar, and in the embodiment, in the hollow interior of the pillar leg plate 136. It is characterized in that an electromagnetic coupling type high frequency pickup 36 is inserted.

As is clear from FIGS. 17 and 18, the high frequency pickup 36 has a structure in which a loop antenna 150 is provided within a case 148 made of a conductor.
48 shields electromagnetic fields from the outside, and has an opening 148a on one side, through which the loop antenna 150 is exposed, and the high-frequency surface current concentrates on the pillar, especially the pillar leg plate 136. They are placed close to each other.

In the embodiment, in order to insert the high frequency pickup 36 into the hollow prism of the pillar leg plate 136, the pillar leg plate 13
An opening 136a is provided in a part of the pillar 6, and the high frequency pickup 36 is inserted into the pillar before the front pillar garnish 146 is fixed.

In order to fix the case 148 of the high frequency pickup 36 to the pillar leg plate 136, brackets 152 and 1514 are fixed to both ends of the case 148 by spot welding or the like, and these brackets 152 and 154 are attached to the pillar leg plate as shown in the figure. 136, firmly tighten the screws.

Therefore, in this fixed upper plate, the loop antenna 1
50 is disposed in a position close to the opposite side of the opening 1363 of the pillar leg plate 136, so that the magnetic flux caused by the high frequency surface current flowing intensively through the pillar leg plate 136 effectively interlinks with the loop antenna 150.

Inside the case 148 is the loop antenna 150 described above.
A circuit section 156 including a preamplifier, etc. is built into the back side of the circuit, and power and signals for controlling the circuit are supplied to this circuit section 156 from a cable 158. The signal is extracted externally from coaxial cable 160 and processed by circuitry similar to that used in the surface M flow distribution described above.

In the embodiment, the loop antenna 150 is a single-turn antenna, and the coil is coated with an insulating coating so that it is placed in close contact with the pillar leg plate 136 in an electrically insulated state. A structure in which the antenna is pressed against the edge of the pillar is preferable, and the magnetic flux generated by the high-frequency surface current that flows concentratedly in the pillar can be efficiently transferred to the loop antenna 150.
can be linked to.

After the high-frequency pickup 36 is installed in the front pillar 38 in the above manner, the front pillar garnish 1146 is attached to the pillar 38, thereby obtaining a structure that is no different in appearance from a normal pillar structure. Can be done.

As described above, according to the embodiment, the high-frequency surface current flowing intensively in the front pillar of a car can be effectively detected by the loop antenna arranged in the longitudinal direction of the pillar, and the antenna device can be completely removed. It is now possible to reliably receive high frequency bands without being exposed to the outside,
It is extremely useful as an automotive antenna.

Other Embodiments In the above embodiments, one
Although a lila coupling type pickup is used, the characteristic feature of the present invention is that an antenna device that detects surface current in the rear roof and pillar peripheral area and receives external waves, which was completely unthinkable in the past, has been obtained. As the high frequency pickup, not only the above-mentioned electromagnetic coupling type but also a capacitive coupling type pickup can be used.

In the case of a capacitively coupled pickup, a detection electrode is arranged along the longitudinal direction of the rear roof and front pillar periphery in each of the above-mentioned parts via an air layer or an insulating plate, and the detection electrode is connected to the surface of the real-7 and front pillar. The high frequency surface current is taken out to the detection electrode side through the electrostatic channel formed between the two, thereby making it possible to take out a high frequency signal of JH in a desired band.

[Effects of the Invention] As explained above, according to the present invention, high-frequency surface currents generated in specific parts of the vehicle body, particularly around the rear roof and front pillars, in response to broadcast waves in a high frequency band, that is, in the FM wave frequency band or above, can be suppressed. Since a die-hacity type broadcast wave receiving antenna is formed using the antenna, it is possible to perform high-quality detection of broadcast waves with high density and low noise, eliminating the need for conventional externally exposed ball antennas and other devices. Therefore, it becomes possible to obtain a small-sized and high-performance automobile antenna device.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a preferred embodiment of the automotive antenna device according to the present invention, FIGS. 2 and 3 are FM band directional characteristics diagrams of the high frequency pickup used in the device shown in FIG. The figure is an explanatory diagram showing the surface current ■ generated in the vehicle body B by the external wave W. Figure 5 is a probe and its processing circuit for determining the distribution of the vehicle body surface current using a probe similar to the high frequency pickup obtained in the present invention. Figure 6 is an explanatory diagram showing the electromagnetic coupling state between the surface current I and the pickup loop antenna, Figure 7 is a characteristic diagram showing the directivity characteristics of the Lubehotena in Figure 6, and Figure 8 is an illustration of the surface current intensity. FIG. 9 is an explanatory diagram showing the direction of the surface current, and FIGS. 10 to 12 are characteristic diagrams showing the car body surface current distribution along the longitudinal section of the car body in FIG. 8. Figures 13 to 15 are explanatory diagrams of a pickup using an electromagnetic coupling type loop anti-thickness as the first high frequency pickup fixed to the rear roof, and Figures 16 to 18 are illustrations of a pickup using an electromagnetic coupling type high frequency pickup as the second high frequency pickup. It is an explanatory view showing a state where a pickup is attached to a front 1-pillar of an automobile. 32... First high frequency pickup 34...
Rear roof 36... Second high frequency pickup 38...
front pillar

Claims (4)

[Claims] (1) A first high-frequency pickup disposed near the rear edge of the right or left side of the rear roof of the automobile along its longitudinal direction, and a front pillar located on the same side as the first high-frequency pickup; a second high-frequency pickup disposed close to each other along the direction; the high-frequency surface current flowing concentratedly near the rear roof periphery and the front pillar due to broadcast waves is received by each of the high-frequency pickups, and the high-frequency wave is in an optimal reception state. A diversity-type automobile antenna device characterized by switching and using a reception signal of a pickup. (2) In the device according to claim (1), the first high-frequency pickup is fixed to the vehicle ceiling panel in a state that is separate from the rear window frame, and the longitudinal length thereof is broadcast. An antenna device for an automobile, characterized in that a loop antenna for a high frequency pickup is disposed near the periphery of a retainer for attaching an edge molding, which is approximately equal to the wavelength of a wave band, along the longitudinal direction of the retainer. (3) In the device according to any one of claims (1) and (2), the second high-frequency pickup includes a loop antenna fixed along the pillar, and the second high-frequency pickup includes a loop antenna fixed along the pillar, and the second high-frequency pickup includes a loop antenna fixed along the pillar. An antenna device for an automobile, characterized in that the magnetic field formed by the loop antenna is electromagnetically detected by the loop antenna. (4) In the device according to any one of claims (1) and (2), the second high-frequency pickup includes a detection electrode arranged closely along the pillar, and detects the high-frequency surface current flowing through the pillar. An antenna device for an automobile characterized in that detection is performed by electrostatic coupling between a pillar and a detection electrode.