JPH05199032A - Plane antenna - Google Patents

Abstract

PURPOSE:To provide the plane antenna in which the sensitivity of a radio wave in a low elevating angle direction is excellent, with less air resistance, ease of mount, simple structure and excellent external appearance. CONSTITUTION:A radiation conductor 3 provided in parallel with a plane ground conductor 2 opposite to each other has a feeding point to fed from a feeding system. A 1st microwave use ceramic dielectric body 20 is provided between a disk shaped ground conductor 2 and the radiation conductor 3. The 2nd ceramic dielectric body 21 for microwave is provided in a ring at the outer circumference of the radiation conductor 3. A slope 21a of the 2nd ceramic dielectric body 21 has a tilt angle and utilizes the prism effect to diffract a radio wave in the low elevating angle direction and receives the diffracted wave. Thus, the radio wave is received with high sensitivity even in the low elevating angle direction being a weak point of the plane antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar antenna, and more particularly to a microstrip antenna used as a mobile communication antenna or the like.

[0002]

2. Description of the Related Art Planar antennas are used in automobiles, aircrafts, etc. because of their low air resistance, good mountability, simple structure, and inconspicuous appearance. As such a planar antenna, for example, a microstrip antenna as disclosed in JP-A-2-156708 is known.

In general, a microstrip antenna for receiving radio waves in the microwave region has a structure as shown in FIG. 11, for example. In this antenna, a ground conductor 2 is formed on the bottom surface of a dielectric 1 such as Teflon or alumina made of a flat plate such as a disc or a square plate, and a radiation conductor 3 is formed on the top surface of the dielectric 1. The ground conductor 2 is grounded by a cable (not shown), and the radiating conductor 3 is a coaxial cable 4.

[0004]

However, in such a conventional planar antenna, when the antenna plane is mounted horizontally with respect to the ground surface, the reception direction of the radio wave is as shown in FIG.
Although the sensitivity is good in the zenith direction as shown by the dotted line C, there is a problem that the sensitivity is low in the low elevation angle region (shown by the diagonal line A) shown in FIG. 11 which is close to the horizontal direction. Further, the microstrip antenna disclosed in Japanese Patent Laid-Open No. 2-156708 is provided with a dielectric for enhancing directivity in the low elevation angle region, but since the dielectric is a flat plate, the sensitivity in the low elevation angle direction is high. Low.

On the other hand, it is a well-known natural principle that the radio wave carrier path is refracted by the prism effect on the boundary surface between the dielectric and air between the electrodes due to the difference in relative permittivity between the two.
The present invention is made by applying such refraction of the radio wave carrier path, that is, the prism effect. Particularly, the sensitivity of radio waves in the low elevation angle direction, which requires high sensitivity, is good, the air resistance is small, and the mounting work is easy. It is an object of the present invention to provide a planar antenna having a good appearance which is easy and has a simple structure.

[0006]

A plane type antenna according to a first aspect of the present invention for achieving the above object is provided with a plane ground conductor and a ground conductor in parallel with each other.
A radiation conductor having a feeding point for feeding from a feeding system;
A first ceramic dielectric provided between the ground conductor and the radiation conductor, and an inclined surface provided in a ring shape on at least an outer peripheral portion of the radiation conductor and refracting radio waves in a low elevation angle direction by utilizing a prism effect to be incident. And a second ceramic dielectric having

The second ceramic dielectric is preferably made of a dielectric material having a dielectric constant higher than that of the first ceramic dielectric. This is because the sensitivity in the low elevation angle direction is improved. In this case, the second ceramic dielectric is preferably made of a high dielectric material having a relative dielectric constant of 10 or more. This is because the sensitivity in the low elevation angle direction is further improved. The inclined surface of the second ceramic dielectric has an inclination angle that does not totally reflect radio waves in the low elevation angle direction.
This is to eliminate radio wave reception failure. Here, the “slope” means a flat surface or a curved surface that is inclined with respect to a horizontal plane. If the ceramic dielectric body is formed by simultaneously molding the first ceramic dielectric body and the second ceramic dielectric body, the manufacturing process is simplified.

A planar antenna according to a second aspect of the present invention is a planar grounding conductor, a radiation conductor provided in parallel with the grounding conductor and having a feeding point for feeding from a feeding system, and A first ceramic dielectric provided between the ground conductor and the radiating conductor and a first ceramic dielectric which is formed integrally with the first ceramic dielectric in a convex ring shape outwardly in the radial direction of the radiating conductor to provide a prism effect. And a second ceramic dielectric for refracting radio waves in the low elevation angle direction for incidence.

A planar antenna according to a third aspect of the present invention is a planar ground conductor, a radiation conductor provided parallel to the ground conductor and having a feeding point for feeding power from a feeding system, and A ceramic dielectric provided between the ground conductor and the radiating conductor, and a circular dielectric provided at least on the outer peripheral portion of the radiating conductor, which has a high permittivity for refracting radio waves in the low elevation angle direction by utilizing the prism effect to enter. And an organic resin dielectric.

The high dielectric constant organic resin dielectric is preferably made of a dielectric material having a relative dielectric constant higher than that of the ceramic dielectric. This is because the sensitivity in the low elevation angle direction is improved. In this case, the organic resin dielectric is preferably made of a high dielectric material having a relative dielectric constant of 10 or more. This is because the sensitivity in the low elevation angle direction is further improved.

A plane type antenna according to a fourth aspect of the present invention is a planar ground conductor, a radiation conductor provided in parallel with the ground conductor and having a feeding point for feeding power from a feeding system, A first organic resin dielectric provided between the ground conductor and the radiation conductor, and an inclined surface provided in a ring shape on at least the outer peripheral portion of the radiation conductor and refracting a radio wave in a low elevation angle direction by utilizing a prism effect to be incident. And a second organic resin dielectric having in this case,
It is desirable that the second organic resin dielectric is made of a dielectric material having a dielectric constant higher than or equal to that of the first organic resin dielectric.

[0012]

According to the planar antenna of the present invention, when the antenna surface is mounted parallel to the horizontal plane, the sensitivity in the zenith direction is good as shown by the solid line B in the schematic diagram of FIG. Compared to the sensitivity of the conventional planar antenna indicated by the dotted line C, it receives radio waves in the low elevation angle direction and even radio waves in the negative elevation angle direction with high sensitivity.

Therefore, when such a planar antenna is installed on a moving body so that the antenna surface is parallel to the horizontal plane, a navigation system using artificial satellites can be used to east and west on the ground, sea, or air on the surface of the earth. The effect is that accurate position information of north and south and height (three-dimensional space) can be obtained.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. An embodiment in which the planar antenna of the present invention is applied to a communication microstrip antenna attached to the body of an automobile will be described. The structure of the microstrip antenna 12 is as shown in FIGS.
The first ceramic dielectric 20 for microwaves has a thin disk shape, and the ground conductor 2 made of a highly conductive material such as Ag, Cu, or Al is formed on the bottom surface thereof. A disk-shaped radiation conductor 3 made of a highly conductive material such as Ag, Cu, or Al is formed on the top surface of the first microwave ceramic dielectric 20.
The ground conductor 2 is grounded by a cable (not shown), and the radiation conductor 3 is connected by a coaxial cable 4 to a vehicle-mounted navigation system control circuit.

As shown in FIG. 2, a second ceramic dielectric material 21 for microwaves is formed in a ring shape on the outer peripheral portion of the radiation conductor 3, and the second ceramic dielectric material 21 corresponds to that of the first ceramic dielectric material 20. It is located around the outer edge. The second ceramic dielectric 21 has a triangular cross section,
It has a slope 21a. The slope 21a has its normal direction inclined upward with respect to the horizontal plane. Regarding the inclination direction of the inclined surface 21a, it is considered that the normal direction of the electric force line formed between the ground conductor 2 and the radiation conductor 3 should approximate the normal direction of the inclined surface. Further, the inclination angle θ of the slope 21 is set to an angle at which a wide-angle radio wave in the low elevation angle direction is incident on the slope 21a without being totally reflected. Therefore, the inclination angle θ of the slope 21 is 30 ° to
The range of 60 ° is desirable, but the inclination angle θ is not limited. As a result, radio waves in the low elevation angle direction, which are difficult to receive on the top surface of the radiation conductor 3, are refracted and incident on the sloped surface 21a of the second ceramic dielectric body 21, so that the prism effect (convex lens effect) is used in the low elevation direction. The sensitivity of radio waves is increased.

Further, the sloped surface 21a also has a function of providing an inclination so that when the protective cover is attached to the microstrip antenna 12, there is no protruding portion and the surface is smooth so as not to impair the appearance of the automobile body. As a modified example of the second ceramic dielectric body, instead of the second ceramic dielectric body 21, for example, the shape shown in FIGS. 5A, 5B, and 5C can be cited. FIG. 5A shows the slope 21.
An example in which b is extended to the top surface 2a of the ground conductor 2, FIG. 5 (B)
Is an example in which a triangular ceramic dielectric 21c is attached to the end of the outer peripheral top surface of the flat plate-shaped first ceramic dielectric 20. FIG. 5C shows the outer peripheral top surface of the first ceramic dielectric 20. This is an example in which a ceramic dielectric 21d having a semicircular cross section is attached at a position slightly on the inner diameter side from the outer peripheral end.
Of course, the shape of the ceramic dielectric of the present invention is not limited to the above shape.

The material of the second ceramic dielectric 21 is
For example, the materials shown in Table 1 are used.

[0018]

[Table 1]

In Table 1, the larger the relative permittivity ε, the better the sensitivity. The dielectric constants ε of the dielectric materials shown in Table 1 are Teflon (ε: 2.5) and alumina (ε:
It is considerably larger than 8-10). According to the microstrip antenna 12, as shown in FIG. 1, since the second ceramic dielectric 21 functions as a prism, the electric wave is refracted as shown by arrows a ₁ and a _{2 in} the figure, and the sensitivity is lowered in the low elevation angle direction. Get better Moreover, since the second ceramic dielectrics 21 shown in Examples 1 to 6 shown in Table 1 are high dielectric materials having a relative permittivity ε of more than 10, they have a highly sensitive radio wave receiving function. Therefore, due to the shape effect (prism effect) and the material effect (dielectric effect) of the second ceramic dielectric 21 due to the specific shape, it is possible to receive radio waves with high sensitivity even in the low elevation angle direction, which is a weak point of the planar antenna. ..

Also, the first ceramic dielectric and the second ceramic dielectric
The first organic resin dielectric and the second organic resin dielectric made of an organic material may be used instead of the ceramic dielectric. In this case, the reception effect at a low elevation angle becomes good due to the prism effect due to the shape effect of the second organic resin dielectric. The dielectric constant of the second organic resin dielectric is preferably higher than that of the first organic resin dielectric.

As the organic resin dielectric material, phenol resin, bakelite, BT resin or the like is used. By using the organic resin dielectric material as described above, the weight can be reduced as compared with the ceramic, and in particular, the total weight of the planar antenna can be further reduced. Therefore, as a portable antenna, there is an effect that performance such as transportability and easiness of handling is improved due to weight reduction.

Next, an example of a method of manufacturing the microstrip antenna 12 will be described with reference to FIG. First, the first ceramic dielectric 20 shown in FIG. 3 (A) is formed into a thin plate by a slurry casting method, a doctor blade method, an extrusion molding method, an injection molding method, a dry pressure molding method, etc. The hole 20a is formed at the portion or the eccentric position. Alternatively, the hole 20a is integrally formed during the molding.

The obtained disk-shaped first ceramic dielectric 2
As shown in FIG. 3B, a disk-shaped ground conductor 2 and a disk-shaped radiation conductor 3 are formed on the bottom surface and the top surface of 0, respectively. In this forming method, for example, a paste material of Cu or Ag is applied and then heated, or the like. Next, as shown in FIG. 3C, the first first ceramic dielectric 20
The second ceramic dielectric 21 is adhered to the outer peripheral edge of the top surface of the. The bonding means for the second ceramic dielectric 21 is, for example, an adhesive or other bonding means.

The reception characteristics of the microstrip antenna 12 are shown in FIG. As shown by the solid line B in FIG. 4, the received signal strength is represented. In the conventional microstrip antenna, as shown by the dotted line C in FIG. 4, the sensitivity in the low elevation angle direction is particularly poor, and it is almost impossible to capture the radio waves of the artificial satellite at an elevation angle of 15 °, for example. On the other hand, according to the microstrip antenna 12 of the present embodiment, as shown by the solid line B, it can be understood that the sensitivity is excellent even in the range of the low elevation angle direction and the negative elevation angle direction.

Next, FIGS. 6 and 7 show microstrip antennas according to the second and third embodiments of the present invention. 6 and 7, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The second embodiment shown in FIG. 6 is an example in which a monolithic microwave ceramic dielectric 30 is used instead of the first ceramic dielectric 20 and the second ceramic dielectric 21 according to the first embodiment. In the second embodiment, the lens portion 30a having a triangular cross-section formed in a convex shape on the outer peripheral apex of the radiation conductor 3 is integrally formed with the disc portion 30b between the ground conductor 2 and the radiation conductor 3. Further, there is an effect that the forming step is omitted and the manufacturability is good.

The third embodiment shown in FIG. 7 is an example in which a ceramic dielectric 32a for microwaves having a semicircular cross section and having a prism effect is integrally formed on the outer peripheral portion of the top surface of the ceramic dielectric 32. Also in such an example, there is an effect that the reception and transmission of a radio wave with a low elevation angle are good. Next, fourth, fifth and sixth embodiments of the present invention are shown in FIGS. 8, 9 and 10, respectively.

The fourth embodiment shown in FIG. 8 is an example of a ceramic dielectric 40 having a disk shape and an H-shaped diametrical longitudinal section when viewed from above. In this example, the ceramic dielectric 40
The disk-shaped radiation conductor 3 is formed on the upper concave surface 40a, and the disk-shaped ground conductor 2 is formed on the lower concave surface b. The ground conductor 2 and the radiating conductor 3 are made of a highly conductive material such as Ag, Cu or Al. In addition, the method for manufacturing the ground conductor 2 and the radiation conductor 3 is formed by, for example, applying a paste material and then heating it. In this example, the ceramic dielectric 4 having a high dielectric constant is formed in a convex ring shape facing upward on the outer periphery of the radiation conductor.
Since 0 is formed, the sensitivity in the low elevation angle direction is good.

The fifth embodiment shown in FIG. 9 is an example in which a recess 50a is provided on the top surface of the ceramic dielectric 50 and the bottom surface 50b is flat. The radiation conductor 3 is formed in the recess 50a, and the ground conductor 2 is formed in the bottom surface 50b. An amplifier 55 that amplifies a radio signal received or transmitted is attached to the bottom surface 50b of the ground conductor 2. Also in the fifth embodiment, the annular convex portion 50c is formed so that the ceramic dielectric 50 provided between the ground conductor 2 and the radiation conductor 3 is convex upward toward the radially outer side of the radiation electrode 3. Because it is formed
The sensitivity in the low elevation direction and the negative elevation direction is good.

The sixth embodiment shown in FIG. 10 is an example in which an amplifier 55 is provided on the lower concave surface 40b of the fourth embodiment shown in FIG. The substrate 54 to which the amplifier 55 is attached is fixed so as to be accommodated in the lower concave space of the bottom surface of the ceramic dielectric 60. As a result, the shape of the bottom surface of this antenna becomes extremely simple and flat, so that there is an effect that the attachability, adhesiveness, handleability, etc. are improved.

Further, in the fourth, fifth and sixth embodiments shown in FIGS. 8, 9 and 10, the ceramic dielectric 40,
Since both 50 and 60 are formed by integral molding,
There is also an effect that the manufacturing process of the antenna is simplified and the manufacturing cost can be reduced. In the above embodiment, although applied to the communication system for automobiles, examples of other mobile objects to which the present invention is applicable include pedestrians, portable transceivers carried by mountaineers and the like, ocean current survey mobile objects, A ship, a helicopter, an airplane, etc. are mentioned. In particular, taxi dispatch system, position detection system for transportation trucks,
It is effective when applied to mobile devices for ocean current surveys.

Further, according to the planar antenna of the present invention, when the antenna body is fitted with the protective cover when it is mounted on the body of the automobile, the slope of the second ceramic dielectric does not stick out from the protective cover. Since a smooth appearance can be formed, there is an effect that the appearance of the automobile body is not impaired.

[0032]

As described above, according to the planar antenna of the present invention, the weakness of the planar antenna is due to the shape effect (prism effect) and the material effect (dielectric effect) of the specific shape of the second ceramic dielectric. The effect is that radio waves can be received with high sensitivity even in the low elevation angle direction.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a microstrip antenna according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a microstrip antenna according to a first embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a manufacturing process of the microstrip antenna according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing the relationship of directivity of the microstrip antenna between the first embodiment of the present invention and the conventional comparative example.

FIG. 5 is a partial schematic cross-sectional view showing a modified example of the second ceramic dielectric body of the present invention.

FIG. 6 is a schematic sectional view showing a microstrip antenna according to a second embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a microstrip antenna according to a third embodiment of the present invention.

FIG. 8 is a schematic sectional view showing a microstrip antenna according to a fourth embodiment of the present invention.

FIG. 9 is a schematic sectional view showing a microstrip antenna according to a fifth embodiment of the present invention.

FIG. 10 is a schematic sectional view showing a microstrip antenna according to a sixth embodiment of the present invention.

FIG. 11 is an explanatory diagram for explaining a radio wave receiving direction of a general microstrip antenna (planar antenna).

[Explanation of symbols]

 2 Ground Conductor 3 Radiating Conductor 12 Microstrip Antenna 20, 40, 50, 60 First Ceramic Dielectric 21, 40, 50, 60 Second Ceramic Dielectric 21a Slope

Claims (11)

[Claims] 1. A planar ground conductor, a radiation conductor provided in parallel with the ground conductor and having a feeding point for feeding power from a power feeding system, and provided between the ground conductor and the radiation conductor. A first ceramic dielectric body, and a second ceramic dielectric body provided in an annular shape on at least an outer peripheral portion of the radiation conductor, the second ceramic dielectric body having an inclined surface for refracting and entering a radio wave in a low elevation angle direction by utilizing a prism effect. A flat antenna characterized by the above. 2. The planar antenna according to claim 1, wherein the second ceramic dielectric body is made of a dielectric material having a dielectric constant higher than that of the first ceramic dielectric body. 3. The second ceramic dielectric has a relative dielectric constant of 1
The planar antenna according to claim 1 or 2, which is made of a high dielectric material of 0 or more. 4. The planar antenna according to claim 1, wherein the inclined surface of the second ceramic dielectric has an inclination angle that does not cause total reflection. 5. The planar antenna according to claim 1, wherein the first ceramic dielectric and the second ceramic dielectric are simultaneously molded. 6. A planar ground conductor, a radiation conductor provided in parallel with and facing the ground conductor, and having a feeding point for feeding power from a power feeding system, and provided between the ground conductor and the radiation conductor. And a first ceramic dielectric body that is integrally formed with the first ceramic dielectric body in a convex ring shape that is directed upward on the outside in the radial direction of the radiation conductor, and refracts radio waves in the low elevation angle direction by utilizing the prism effect. A planar antenna, comprising: a second ceramic dielectric that is incident upon. 7. A ground conductor having a planar shape, a radiation conductor provided in parallel with the ground conductor and having a feeding point for feeding power from a power feeding system, and provided between the ground conductor and the radiation conductor. And a high dielectric constant organic resin dielectric that is provided in a ring shape on at least the outer peripheral portion of the radiation conductor and that refracts radio waves in the low elevation angle direction by using the prism effect to enter. A characteristic planar antenna. 8. The planar antenna according to claim 7, wherein the organic resin dielectric is made of a dielectric material having a dielectric constant higher than that of the ceramic dielectric. 9. The planar antenna according to claim 7, wherein the organic resin dielectric is made of a high dielectric material having a relative dielectric constant of 10 or more. 10. A planar ground conductor, a radiation conductor provided in parallel with the ground conductor and having a feeding point for feeding power from a power feeding system, and provided between the ground conductor and the radiation conductor. A first organic resin dielectric and a second organic resin dielectric provided in a ring shape on at least the outer peripheral portion of the radiation conductor and having a slope for refracting and entering radio waves in the low elevation angle direction by utilizing a prism effect. A planar antenna characterized by being provided. 11. The planar antenna according to claim 1, wherein the second organic resin dielectric is made of a dielectric material having a dielectric constant higher than that of the first organic resin dielectric.