JP2001189616A - Glass antenna for microwave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass antenna for microwave, with which production is facilitated and productivity is improved. SOLUTION: A radiation conductor 2 and a ground conductor 3 are located while facing each other across a dielectric intermediate layer 1. A feed conductor 4 is located while being protruded from the radiation conductor 2 through an opening formed on the dielectric intermediate layer 1 and the ground conductor 3, and a microstrip line is formed from the radiation conductor 2 and the ground conductor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave glass antenna having an antenna function for transmitting or receiving microwaves to a window glass of a vehicle such as an automobile or a building. The present invention relates to an improvement in a glass antenna suitable for a laminated glass or a multi-layer glass obtained by laminating glass substrates.

[0002]

2. Description of the Related Art In recent years, the environment surrounding transportation systems has entered a period of change. Automobiles are becoming more intelligent and computerized rapidly, and in the early 21st century, the intelligent road system ITS (Intelligen
(Transport System) is also accelerating. The main component system of ITS is the automatic toll collection system ETC (Electrical Toll Collection), which collects road usage fees by transmitting and receiving information such as toll information, vehicle type information, ID number, etc. using high-frequency radio waves (5.8 GHz band). Is what you do. In this ETC system, the vehicle-side installation device includes an IC card, an IC card terminal, and an antenna. At this time, 5.8GHz band (5.795 ~
Antennas tuned to 5.845 GHz) are essential. The IC card terminal is usually installed on a dashboard, and a chip type or microstrip antenna built in the IC card terminal is considered as an ETC antenna.

[0003]

However, this type of ET
In the C system, the ETC antenna is built into the IC card terminal separately from the antenna installed outside the vehicle, so the IC card terminal itself must have an antenna function, so the IC card terminal Becomes expensive, ET
There is a technical problem that the C system becomes complicated. In order to solve such a technical problem, there is conceivable a means in which the ETC antenna itself is configured as, for example, a glass antenna of an automobile so that the IC card terminal side does not need to have an antenna function.

As a prior example in which a microstrip antenna is configured as a glass antenna, a technique has been proposed in which a microstrip antenna is configured by using one glass substrate such as laminated glass as a dielectric layer. (See, for example, German Patent DE 3834075, Japanese Patent Publication No. 9-502073). However, in this type of prior example, conductors for forming a microstrip antenna must be formed on both front and back surfaces of the glass substrate, but it is not possible to form conductors on both surfaces of the glass substrate by screen printing or the like. However, there is a risk that the printed pattern may be damaged in the process of transporting the glass substrate, and there is a technical problem that it is very difficult in the manufacturing process.

In the above-mentioned prior art, a means for integrating the antenna portion and assembling it on the surface of the laminated glass has also been proposed. In addition, since an adhesive layer or a fixing jig for attaching the antenna portion is required, there are technical problems such as an increase in the number of steps and an increase in the amount of material used.

Incidentally, such a technical problem is not limited to a glass antenna for a vehicle such as an automobile, but also arises similarly for a glass antenna provided on a window glass of a building such as a building. The present invention has been made in order to solve the above technical problems, and focuses on the structure of a laminated glass obtained by laminating at least a pair of glass substrates via a dielectric intermediate layer. Provided is a microwave glass antenna capable of improving productivity.

[0007]

That is, the present invention relates to a microwave glass antenna provided on a laminated glass obtained by laminating at least a pair of glass substrates with a dielectric intermediate layer interposed therebetween, and comprising: The radiating conductor and the ground conductor are opposed to each other with the layer interposed therebetween, and the feed conductor is arranged so as to protrude from the radiating conductor through openings such as holes and cutouts formed in the dielectric intermediate layer and the ground conductor. The microstrip line is formed by the above.

In such technical means, laminated glass includes laminated glass and double glazing. Laminated glass is glass widely used in vehicles such as automobiles and buildings such as buildings. The configuration is, for example, a configuration in which an organic film is sandwiched between two glass substrates.
As an organic film, for example, polyvinyl butyral (PV
B: A dielectric such as Polly Vinyl Butylar) is used. For example, PVB with a thickness of 0.38 to 1.54 mm is generally used,
Especially in Japan, 0.76 mm thick laminated glass for automobiles is used. In addition, double glazing is a glass whose use rate is rapidly increasing in recent years for buildings such as houses and buildings from the viewpoint of adjusting the indoor air temperature and improving the cooling / heating efficiency. The structure is such that a dry air layer or a vacuum portion is provided between two glass substrates. Further, the application of the laminated glass of the present invention is not limited to vehicles and buildings, but may be other applications such as liquid crystal display glass. Although the present invention is directed to a glass antenna, the substrate material is not limited to glass, but may be any other dielectric material.

The dielectric intermediate layer includes not only a tangible dielectric such as PVB but also an intangible dielectric such as an air layer. Here, the dielectric intermediate layer is not limited to a single type, and a plurality of types may be used. When an intangible dielectric is used, a tangible dielectric may be interposed between the glass substrates to secure an air layer of the intangible dielectric inside.

Further, the radiation conductor and the ground conductor may be disposed to face each other with the dielectric intermediate layer interposed therebetween. In this case, as a method of manufacturing each conductor, a radiation conductor and a ground conductor may be provided inside a pair of glass substrates sandwiching the dielectric intermediate layer, respectively, or the dielectric material constituting the dielectric intermediate layer may be provided. Each conductor may be provided on both sides of the sheet, and may be appropriately selected such that it is sandwiched between a pair of glass substrates.
In consideration of manufacturability, it is preferable that a microstrip antenna element in which conductors are provided on both surfaces of a dielectric sheet is preliminarily configured, and the microstrip antenna element is incorporated at the stage of a glass substrate joining process.

Further, the radiation conductor and the ground conductor may be appropriately selected as long as they form a microstrip line. Here, that both conductors form a microstrip line means that both conductors constitute a microstrip antenna, and at the time of reception, a received signal is captured by a voltage generated between a radiation conductor and a ground conductor, At the time of transmission, radio waves are radiated by applying a voltage of a transmission signal between both conductors. At this time, the antenna function of the present invention may correspond to any frequency, but it is particularly effective for radio wave transmission / reception performance in a frequency GHz band (microwave band), for example, a frequency of 1.0 to 10.0 GHz. Bands are preferred.

[0012] For the design of the radiation conductor, the ground conductor, or the dielectric intermediate layer, it is possible to apply the existing microstrip antenna design formula. That is, a microstrip antenna (MSA: Micro Strip)
Antenna) positively utilizes the transmission loss of a microstrip path (MSL: Micro Strip Line), which is a high-frequency transmission path, for radio wave radiation. For example, as shown in FIG.
A certain distance between the radiation conductor 2 and the ground conductor 3 (dielectric intermediate layer 1
(Equivalent to the thickness of the ground conductor 3), and has the characteristic of emitting radio waves in the direction opposite to the ground conductor 3. In FIG. 6, reference numeral 4 denotes a power supply conductor connected to the radiation conductor 2, which is arranged in non-contact with the ground conductor 3.

Here, the thickness between the conductors 2 and 3 is defined as h [m
m], the length of the radiation conductor 2 is a [mm], and the frequency (resonance frequency) of a radio wave capable of radiating with high efficiency is fr [Hz].
The width w [mm] (not shown) of the radiating conductor 2 has little relation to the frequency of the radiated radio wave. For example, in the case of a square, w ≒ a unless otherwise specified. Equations (1) to (3) shown in Equation 1 below are widely known square MSA design equations. Note that these equations are obtained when a dielectric such as a glass substrate does not exist on the surface of the radiation conductor 2 (εr = 1.0
This is the design equation for the case of air.

[0014]

(Equation 1)

Further, assuming that the characteristic impedance of the microstrip path is Z ₀ , Z ₀ is expressed as follows. Z ₀ = 377 / (√εeff [w / h + 1.393 + 0.677ln (w / h + 1.444)]) where εeff = (εr + 1) / 2 + (εr-1) / 2 (1 + 12h / w) -1/2

As described above, by adjusting the dimension a of the radiation conductor 2 and the distance h between the radiation conductor 2 and the ground conductor 3, it is possible to radiate the frequency with high efficiency.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. First Embodiment FIG. 1 shows a microwave glass antenna according to a first embodiment of the present invention. In the figure, a glass antenna is a glass antenna for an automobile, and a glass 5 of this example is made of a pair of glass substrates 5a and 5b (5a: outer glass substrate, 5b: inner glass substrate) made of polyvinyl butyral (PVB). It is a laminated glass laminated with a dielectric intermediate layer 1 interposed therebetween. On the other hand, the glass antenna of this example has a microstrip antenna element (hereinafter, referred to as an MSA element as required) 10 incorporated in the dielectric intermediate layer 1 and is sandwiched between a pair of glass substrates 5a and 5b. It is. 1A is an explanatory front view of the vehicle exterior glass substrate 5a partially cut away, and FIG. 1B is an explanatory sectional view taken along line BB in FIG. 1A.

In the present embodiment, the dielectric intermediate layer 1
Is such that a part of a dielectric intermediate film 11 made of, for example, PVB is cut out in a rectangular shape, and the MSA element 10 is fitted into a portion corresponding to the cutout opening 12 (see FIG. 2). As shown in FIGS. 1 and 2, the MSA element 10 has a rectangular dielectric sheet 1 made of, for example, PVB.
For example, a rectangular radiating conductor 2 is provided on a part of the outer surface of the vehicle 3, while a ground conductor 3 is provided on the entire inner surface of the dielectric sheet 13, and the dielectric sheet 1 in a region corresponding to the radiating conductor 2 is provided.
A power supply through hole 14 is formed in a part of the ground conductor 3 and the ground conductor 3, and a power supply conductor 4 (in this example, a pin configuration) penetratingly arranged through the power supply through hole 14 is provided on the vehicle interior surface of the radiation conductor 2. The ground conductor 3 is formed so as to protrude in a non-contact state. In this case, FIG.
As schematically shown in FIG. 1, the radiation conductor 2 and the ground conductor 4 sandwiching the dielectric sheet 13 form a microstrip line.

Here, as the dielectric intermediate layer 1, glass 5
By using a dielectric having a higher dielectric constant (for example, a dielectric ceramic having a high perovskite structure), it is possible to reduce the size of the radiation conductor 2 (see (1) above).
See formula). The radiation conductor 2 and the ground conductor 3 may be formed by baking a conductive paste, or may be appropriately selected by using a conductive foil, a conductive film, a conductive thin film, a conductive plate, or the like. Further, the power supply conductor 4 may be connected to the radiation conductor 2 by appropriate means such as soldering, welding, or integral molding.

Further, a connector opening 20 is formed in the vehicle interior glass substrate 5b by punching or cutting out the glass substrate 5b.
The power supply conductor 4 is arranged so as to protrude therein, and a conductive tubular connection connector 21 is provided around the power supply through hole 14 of the ground conductor 3 in a non-contact manner with the power supply conductor 4.
Note that the connection connector 21 has a male screw portion in the outer cylinder portion. On the other hand, a coaxial cable 22 is connected to a communication device that enables reception and transmission inside the vehicle.
2 of the coaxial cable 22 is screwed to the connection connector 21, an outer conductor (not shown) of the coaxial cable 22 is connected to the ground conductor 3 via the connection connector 21, and an inner conductor ( (Not shown) is connected to the power supply conductor 4.

As will be described later, the position of the feed conductor 4 with respect to the radiation conductor 2 is set at a position deviated (offset) from the center of the radiation conductor 2 to any position so as to match the impedance characteristics. It is preferable to select one.

Next, a manufacturing process of the glass antenna according to the present embodiment will be described. In the present embodiment,
As shown in FIG. 2, the manufacturing process of the glass antenna
An MSA element forming step of forming the A element 10;
It comprises a laminated glass sealing step of sealing the A element 10 between the glass substrates 5a and 5b, and a laminated glass pressing step of finally bonding the glass substrates 5a and 5b.

Here, the MSA element forming step is performed, for example, through the following steps. Adhesive copper foils serving as the radiating conductor 2 and the ground conductor 3 are attached to both surfaces of the dielectric sheet 13, and power supply through holes 14 are opened in the dielectric sheet 13 and the ground conductor 3. Then, the power supply conductor 4 is passed through the power supply through hole 14 formed in the dielectric sheet 13 and the ground conductor 3, and the power supply terminal 4 and the discharge conductor 2 are connected by soldering or the like. Thereafter, the ground conductor 3 around the power supply through-hole 14 is formed.
To the connector 21 by soldering or the like. At this stage, the MS including the connector 21
The A element 10 is completed.

Next, the laminated glass enclosing step is performed, for example, through the following steps. First, the inside of the dielectric intermediate film 11 is cut out corresponding to the shape of the MSA element 10. Thereafter, the connector opening 2 is formed in the vehicle interior glass substrate 5b.
Open 1 The outer glass substrate 5a and the dielectric interlayer 11
After the MSA element 10 is fitted into the hollow opening 12 of the dielectric intermediate film 11, the car interior glass substrate 5b is laminated. Thereafter, the set that was laminated in the previous process is attached with, for example, tape so as not to be displaced, and is placed in a vacuum pack such as a plastic bag. Then, a vacuum is drawn, and the vacuum pack is heated and pressurized.

Finally, a laminated glass pressing step, that is,
A set of laminated glass in a vacuum pack is placed in an autoclave, and the laminated glass is pressed and completed.

In such a manufacturing process, in the laminated glass encapsulating process, the already prepared MSA element 10 is merely encapsulated between the glass substrates 5a and 5b for laminated glass, and thereafter, it is produced in the same manner as ordinary laminated glass. And productivity is remarkably improved. In this regard, in the conventional method for manufacturing a glass antenna, since the MSA element must be formed together with the glass substrate in the manufacturing process of the laminated glass, the productivity is significantly reduced.

In this embodiment, FIG.
As shown in (a), the MSA element 10 is formed on a small dielectric sheet 13, so that the manufacturing apparatus itself of the MSA element 10 can be reduced in size.
As shown in FIG. 3B, the MSA element 10 may be formed for the dielectric intermediate film 11 itself constituting the dielectric intermediate layer 1. By doing so, it is possible to omit a process such as forming a hollow opening 12 in the dielectric intermediate film 11.

The operation of the glass antenna according to this embodiment will be described. Now, when power is supplied to the radiation conductor 2 through the power supply conductor 4, the length of the radiation conductor 2 (see FIG. 6A) and the thickness between the conductors 2 and 3 (see FIG. 6H) are appropriately set. Otherwise, it functions as a microstrip antenna and can radiate frequency with high efficiency. Here, since the glass substrate 5a on the radiation conductor 2 side is a dielectric, the wavelength of the transmitted / received radio wave is determined by the effect of shortening the wavelength of the dielectric (effect of delaying the propagation speed of the electromagnetic wave in the dielectric) by the presence or absence of the glass. It is estimated that the resonance wavelength of (MSA) changes. For this reason, when resonating with radio waves of the same wavelength, it is necessary to make the size of the radiation conductor 2 smaller when glass is present than when there is no glass. Further, in the present embodiment, it is possible to function as an MSA even if there is no glass in a portion corresponding to the radiation conductor 2 in the laminated glass substrate 5a. At this time, in order to configure an aspect without glass in a portion corresponding to the radiation conductor 2, the glass substrate 5a is shifted, hollowed out,
It can be realized by a method such as notching.

Further, with respect to the comparative form model and the embodiment model shown in FIGS.
When the reflection coefficient for q. was examined, the results shown in FIG. 4 were obtained. Here, FIG. 5A shows a rectangular ground conductor 3 having one side of k, and one side of d (15.4 mm in this example).
5B, and a comparative form model in which the feed conductor 4 is provided at the center of the radiating conductor 2, and FIG.
, And a rectangular radiating conductor 2 on one side d, which is 3 mm in length and width (3 mm in this example) from the end of the radiating conductor 2.
The power supply conductor 4 is provided with a deviation (offset) only by
This is an embodiment model excluding the glass substrate 5a on the power supply conductor 4 side.

In FIG. 4, the solid line shows the embodiment model (FIG. 5B), and the dotted line shows the comparison model of the central power supply. According to the figure, the model of the present embodiment (FIG. 5)
In (b)), a sufficient reflection coefficient is obtained near the frequency of 5.5 [GHz], and it is understood that good antenna performance is obtained. The reason why a sufficient reflection coefficient cannot be obtained in the case of the comparative morphological model (central power supply) is that the impedance usually needs to match 50Ω, but in the case of central power supply, the impedance is abnormally higher than 50Ω. This is due to the fact that it becomes a dance and cannot match the impedance characteristics.

The structure of the dielectric intermediate layer 1 is as follows.
The present invention is not limited to the above embodiment, and the design may be changed as appropriate, for example, by using a dielectric material other than PVB (for example, Teflon). Further, in the case of a double-glazing glass for architectural purposes, a dry air or vacuum dielectric layer may be provided between the glass substrates 5a and 5b instead of the dielectric sheet 13 of FIG. . This is preferable in that a dielectric material is unnecessary and higher radiation efficiency can be obtained.

[0032]

As described above, according to the present invention, attention is paid to the structure of a laminated glass laminated on at least a pair of glass substrates with a dielectric intermediate layer interposed therebetween, and microstructures are formed using the dielectric intermediate layer. Since the strip antenna is configured, it is possible to easily form a microstrip antenna for microwaves, and accordingly, it is possible to reliably provide a glass antenna that is easy to produce and can improve productivity. can do.

[Brief description of the drawings]

FIG. 1A is a front view of a microwave glass antenna according to a first embodiment, and FIG. 1B is a cross-sectional view taken along line BB.

FIG. 2 is an exploded configuration diagram of the glass antenna according to the first embodiment.

FIG. 3A is a schematic diagram of a glass antenna according to the present embodiment, and FIG. 3B is a schematic diagram showing a modification thereof.

FIG. 4 is an explanatory diagram showing a measurement result of a reflection coefficient of each model shown in FIGS.

FIGS. 5A and 5B are explanatory diagrams showing a measurement model of a reflection coefficient.

FIG. 6 is an explanatory diagram showing a basic configuration (microstrip antenna (MSA)) of a glass antenna according to the present invention.

[Explanation of symbols]

1 ... dielectric intermediate layer, 2 ... radiation conductor, 3 ... ground conductor, 4
... power supply conductor, 5 (5a, 5b) ... glass, 10 ... MSA
(Microstrip antenna) element. 11 dielectric intermediate film, 12 hollow opening, 13 dielectric sheet, 14
... Power supply through hole, 15 ... Dielectric layer, 20 ... Connector opening, 21 ... Connector, 22 ... Coaxial cable, 23 ...
Tip connector

Claims (1)

[Claims] 1. A microwave glass antenna provided on a laminated glass obtained by laminating at least a pair of glass substrates with a dielectric intermediate layer interposed therebetween, comprising: a radiation conductor and a ground conductor sandwiching the dielectric intermediate layer. And a feed conductor is projected from the radiation conductor through an opening formed in the dielectric intermediate layer and the ground conductor, so that a microstrip line is formed by the radiation conductor and the ground conductor. Glass antenna for microwave.