JPH07183719A - Omnidirectional antenna - Google Patents

Abstract

PURPOSE:To increase the gain in the direction parallel with an antenna element by the control of the beam width in the perpendicular direction by providing the antenna element, which has an earth conductor and is formed into an approximately plane plate, and a conductive ground body extended from the earth conductor to the opposite side of the element. CONSTITUTION:A ground body 40 is extended from the earth conductor of an element 12. A micro strip antenna MSA having the element which has a radiation conductor formed on one face and has the grounding conductor formed on the other face radiates a radio wave by the magnetic current wall generally formed between both or these conductors. In this example, the current is generated along the ground body 40 extended approximately perpendicularly to the grounding conductor. The gain in the direction approximately parallel with the element 12 is increased. When this device is arranged in the place with a fine view of a vehicle, the beam width in the perpendicular direction is controlled by the ground body 40, and as the result, the directivity of a small elevation angle is improved. Consequently, the measurement performance is improved even if a sufficient number of reception satellites cannot be obtained by a conventional device because of a relatively poor satellite arrangement condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reception from GPS satellites and satellite EPIRB (Emergency Position Indicating).
Radio Beacon) etc., and improvement of the omnidirectional directional antenna used for communication with orbiting satellites.

[0002]

2. Description of the Related Art GPS is a navigation system that receives radio waves from a predetermined number of GPS satellites launched and informs the operator of a mobile body of the position. That is, data such as ephemeris is received from GPS satellites, and the current position of the moving body is displayed on the display screen. Examples of the moving body on which the GPS receiver is mounted include ships and automobiles.

Positioning algorithms based on GPS include two-dimensional positioning and three-dimensional positioning. In a state where radio waves can be satisfactorily received from at least four of the predetermined number of GPS satellites, three-dimensional positioning is performed by four satellites. That is, the pseudo-range with four satellites is obtained, the clock offset is further corrected, and the position of the moving body is three-dimensionally determined. In the case of two-dimensional positioning, the earth is used instead of one satellite which is in short supply.

Therefore, no matter which positioning method is adopted, it is necessary to be able to receive radio waves from 3 to 4 GPS satellites.

An omnidirectional directional antenna is used for simple mobile communication using satellite-based EPIRB and orbiting satellites. In these systems, the positional relationship with the target satellite is constantly changing, and the EPIRB and the moving body oscillate. Therefore, the antenna must ensure the required gain over a wide angular range in the vertical plane. Conventionally, a 4-wire helical antenna has been used as an antenna that realizes such characteristics.

[0006]

However, the conventional GPS
However, the gain in the low elevation angle direction was low due to the directivity of the receiving antenna, and there was a case where the reception probability of radio waves from a satellite with a low elevation angle could not satisfy the requirement of 3 to 4 downlinks.

Further, the antenna used in the mobile communication utilizing the satellite EPIRB or the orbiting satellite does not always have sufficient directivity, and its structure is complicated and has a protruding shape. Therefore, it was difficult to handle in operation, and it was difficult to integrate it with the transceiver. That is, it was difficult to operate in the low elevation direction.

A simple antenna used in these systems is a microstrip antenna (hereinafter referred to as M
There is a thin planar antenna such as SA), but when this type of planar antenna is arranged on, for example, the ceiling of an automobile, the low elevation angle gain is reduced.

The present invention has been made to solve the above problems, and improves the directivity of a flat plate antenna such as MSA by a simple means to obtain a gain in a desired elevation angle direction. In order to eliminate the above-mentioned inconveniences, it is possible to realize a hemispherical directivity that secures the above-mentioned characteristics and to improve electrical performance such as simplification of equipment and reduction of power supply loss by integrating with a transmitter and / or a receiver. To do.

[0010]

In order to achieve such an object, the antenna of the present invention has a substantially flat plate-shaped antenna element having a ground conductor, and extends from the ground conductor of the antenna element to the side opposite to the antenna element. And an electrically conductive ground body.

A second aspect of the present invention is characterized in that a circuit for processing a signal related to the antenna element is arranged in a space inside the ground body.

A third aspect of the present invention is characterized by comprising a shielding lid for shielding the space inside the ground body.

A fourth aspect of the present invention is characterized in that the antenna according to the first to third aspects is mounted on a moving body such as an automobile, and the antenna transmits and / or receives radio waves from a satellite. .

[0014]

In the antenna of the present invention, a conductive ground body is extended from the ground conductor of the antenna element to the side opposite to the element. Therefore, the current generated between the conductors in the antenna element is deformed along the ground body, and the gain in the direction close to the element is improved. That is, since the beam width of the element in the vertical direction is controlled by the ground body, M
Omnidirectional directivity can be obtained in an antenna having a substantially flat plate shape such as SA.

Further, in the present invention, a circuit related to the antenna element, for example, a circuit such as a transmitter and a receiver is provided in the space inside the ground body. Thereby, the space is effectively used, the device configuration is simplified, and the power feeding loss is reduced. Further, since the ground body functions as a shield, it also reduces interference with the outside.

In the third aspect, since the space inside the ground body is shielded by the shielding lid, the shielding action in the second aspect becomes more remarkable.

According to the present invention, since the antenna according to any one of claims 1 to 3 is mounted on a moving body such as an automobile, radio waves from a satellite with a low elevation angle can be suitably received by GPS, and positioning by GPS is possible. It becomes difficult for a difficult state to occur.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

1 to 3 show the structure of the MSA according to the first embodiment of the present invention. Of these figures,
1 is a vertical cross section taken along a plane parallel to the receiving PC board 10, FIG. 2B is a vertical cross section taken along a plane perpendicular to FIG. 1, and FIG. The DD cross section of (b) is shown in FIG.
1A is the CC cross section of FIG. 1, and FIG. 3C is the B cross section of FIG.
B-sections are shown respectively. In addition, FIG.
FIG. 4 is a diagram illustrating a mounting state of the preamplifier unit 14 on the MSA element 12.

In this embodiment, the MSA element 12 is a circular element. A radiation conductor is formed on one surface (upper surface in FIGS. 1 and 2B) of the element 12, and a ground conductor is formed on the back surface (not shown). Power feeding is performed from the surface on the ground conductor side, and the preamplifier section 14 provided on the surface on the ground conductor side outputs the output of the element 12 to a high frequency (R
F) Amplify.

The preamplifier section 14 is connected to the receiving section 20 on the receiving section PC board 10 via the wiring 16 and the connector 18. The receiver 20 is electromagnetically shielded for handling RF signals. The receiving unit 20 inputs the RF output of the preamplifier unit 14 via the connector 18, and executes processes such as RF amplification, conversion to an intermediate frequency (IF), and IF amplification. The IF output of the reception unit 20 is processed by the reception processing unit 34 and then output to the outside via the cable 22. For example, when this embodiment is used as an in-vehicle GPS receiving antenna, as shown in FIG.
2 is introduced into the passenger compartment 24 and connected to the display device 30. The display control unit 26 uses the small display 30 such as a small CRT or a liquid crystal display to display the positioning result as, for example, latitude or longitude information, or map information based on the signal subjected to the baseband processing or the like by the reception processing unit 34. And display it on top of.

The preamplifier section 14 and the receiving section 20 operate by receiving power supply from the power supply section 32. The power supply section 32 and the reception processing section 34 are mounted on the power supply section PC board 36 or the reception processing section PC board 38, respectively.
Is the lower part of the figure, and the reception processing unit PC board 38 is the reception unit PC board 1
It is arranged parallel to 0.

The assembly structure of this embodiment will be described in more detail as follows. First, the ground body 40 formed of a cylindrical metal is attached and extended from the ground conductor of the element 12 in the direction opposite to the radiation conductor. The ground body 40 is a member according to the features of the present invention, and its operation will be described later. The element 12 and the ground member 40 are attached by, for example, an insulating rivet as shown in FIG.

Receiving section PC board 10 and receiving processing section PC board 3
8 is fixed to the element 12 by an upper fixture 42 as shown in FIG. The upper fixture 42 is arranged on the side of the ground conductor surface of the element 12, and the preamplifier unit 1
4 has a substantially rectangular hole in the central portion so that 4 can be attached and fixed to the element 12. The upper fixture 42 sandwiches and fixes the reception section PC board 10 and the reception processing section PC board 38, so that these PC boards 10 and 38 are fixed to the internal space of the ground body 40.

The lower part of the ground body 40 is a lower fixing device 4.
It is fixed to the mounting seat 46 of No. 4 by screwing. The lower fixture 44 includes the reception unit PC board 10 and the reception processing unit PC board 3.
8 is sandwiched, and thereby the lower portions of the PC boards 10 and 38 are fixed. Below the PC boards 10 and 38, a conductor shielding cover 47 for shielding the internal space of the ground body 40 is arranged. The lower fixture 44 is further screwed to the mount base 48.

The mount base 48 has a hole in the center thereof, and the cable 22 is pulled out from this hole. The cable 22 is inserted into this hole via the fixture 50 and the packing 52. At the bottom of the mount base 48, a mounting screw hole is provided. Further, as shown in FIG. 2B, the mount base 48 has a power source P
The C plate 36 is screwed and fixed.

These structures are further covered with an antenna radome 54. The antenna radome 54 is
It is a member for protecting the element 12 and other components from rain and the like, and is made of a material capable of transmitting radio waves from a satellite. The antenna radome 54 is fixedly mounted on the mount base 48. In order to prevent the entry of moisture or the like, the contact portion between the antenna radome 54 and the mount base 48, the contact portion between the antenna radome 54 and the lower fixing tool 44, the contact portion between the mount base 48 and the lower fixing tool 44, etc. , Place the waterproof member.

The most significant feature of this embodiment is that the ground body 40 extends from the ground conductor of the element 12. An MSA having an element in which a radiation conductor is formed on one surface and a ground conductor is formed on the other surface generally radiates radio waves by a magnetic current wall formed between both conductors. In the MSA 28 of this embodiment, a current is generated along the ground body 40 extending almost at right angles to the ground conductor.
This current increases the gain in the direction parallel to the element 12.

In particular, when used as a vehicle-mounted GPS receiving antenna as shown in FIG. 4, when the MSA 28 is placed in a good vantage point (roof or the like) of the vehicle and the element 12 is used in a substantially horizontal state, Body 40
As a result of controlling the beam width in the vertical direction, the directivity at a low elevation angle is improved. Therefore, even if the satellite arrangement is relatively poor and the conventional MSA cannot obtain a sufficient number of receiving satellites, according to the present embodiment, it is possible to receive radio waves from a satellite with a low elevation angle at a sufficient level. , Positioning performance is improved.

The present invention is not limited to GPS.
That is, the present invention can be applied to a communication system, a navigation system, etc. that needs to receive and / or receive a radio wave incident at a low elevation angle.

Further, the present invention does not require the shape and structure of the ground body to be limited. For example, in FIG.
In the second embodiment shown in (a), the ground body 56 has a tapered shape that opens downward, and for example, in the third embodiment shown in FIG. 5 (b), it has a tapered shape that opens upward.
Even with such a shape, the effects of gain improvement and directivity improvement similar to those of the first embodiment can be obtained. Which shape is selected can be selected by design. In addition, the first to third embodiments
In the examples, the ground body was a tubular conductor. Instead of this, for example, a cage-like structure in which rod-shaped conductors are arranged at intervals of about λ / 10 (λ: reception wavelength) may be used. Moreover, you may use a mesh of suitable eyes. That is, it is sufficient if it has a function of bending the current. Of course, the sectional shape of the ground body is not limited to the circular shape.

Furthermore, the present invention is not limited to the shape and structure of the MSA element. Therefore, the conventional MSA element as shown in FIG. 6A is sufficient. This MSA
The element 60 includes a radiation conductor 6 on the upper surface of a circular dielectric substrate 62.
4 and the ground conductor 66 is adhered and formed on the lower surface. The dielectric substrate 62 may have a relative permittivity of about 2 to 3, but it can be downsized by using a material having a higher relative permittivity. The radiation conductor 64 has a degenerate separation element 68 for generating circularly polarized waves, and power is supplied from a point 70 on a line inclined by 45 ° with respect to a straight line connecting the degenerate separation element 68 and the center of the radiation conductor 64. ing. When the feeding point 70 is provided at the center of the radiation conductor 64, the input impedance becomes 0,
Since it becomes infinite when it is provided at the end, impedance can be matched by selecting the location at which the feeding point 70 is provided.

Further, as shown in FIG. 6B, the matching element 7 is placed on a straight line connecting the feeding point 70 and the center of the radiation conductor 64.
The MSA element 74 provided with 2 may be used. Matching element 7
2 is provided in the peripheral portion of the radiation conductor 64, and is formed of a conductor having a size of about λ / 100 in the diameter direction and about λ / 10 in the width direction. The addition of such a conductor has little effect on the amplitude and phase of the current and does not affect the directivity, but the operating frequency is a little (0.1%).
Shift). Therefore, the impedance matching can be easily obtained by adjusting the matching element 72. The MSA element 74 having such a structure is particularly effective when the substrate 62 having a high dielectric constant that makes it difficult to obtain impedance matching is used. That is, MSA while reducing costs
This matching element is effective when it is desired to reduce the size.

As the MSA element, in addition to the circular element as shown in FIGS. 6 (a) and 6 (b), FIG.
Square elements such as (e) can be used. Further, the degenerate separation element may be as shown in FIGS. 6 (d) and 6 (f).

In addition, the present invention is not limited to MSAs. That is, since the antenna according to the present invention excites the ground conductor having a structure in which the ground body is extended on the side opposite to the element by the plate-shaped element to enable control of the beam width in the element vertical direction, Not limited to this, any thin antenna having a substantially flat plate shape can be applied.

FIG. 7A shows the structure of the antenna according to the fourth embodiment of the present invention. The antenna shown in this figure is a printed cross dipole antenna, and has a configuration in which a cross dipole 78 is arranged on the upper side and a reflector 80 which is a ground conductor is arranged on the lower side through a dielectric 76.
A cylindrical ground body 82 extends from the reflection plate 80 on the side opposite to the cross dipole 78.

Further, FIG. 7B shows the structure of the antenna according to the fifth embodiment of the present invention. The antenna shown in this figure is a cross slot antenna, and the cross dipole 78 in the fourth embodiment is replaced by the cross slot 8.
4 has a configuration replaced with 4.

In any of these structures, the beam width in the vertical direction can be controlled by using the cross dipole 78 or the cross slot 84 as an exciting element, and the directivity can be improved. Of course, a circuit may be arranged inside the ground body 82 or a shielding lid may be used. When transmitting and receiving as in communication with an orbiting satellite, the frequency band of the antenna element to be excited may be narrow and unusable. In that case, a two-stage stacked microstrip antenna or an annular patch antenna shown in FIG. 7E can be used as the excitation antenna. It should be noted that reference numerals 86 and 88 denote first and second patch antennas, respectively. Other than these, as the thin plate antenna to which the present invention can be applied, the short helical shown in FIG. 7C, the plane spiral shown in FIG. 7D, and the like can be given.

[0039]

As described above, according to the antenna of the present invention, since the ground body is extended from the ground conductor of the element, the current generated between the ground conductor and the radiation conductor is deformed along the ground body, By controlling the beam width in the vertical direction, the gain in the direction close to the element is improved.

Further, according to the second aspect, since the circuit (transmitting unit, receiving unit, etc.) related to the element is provided in the space inside the ground body, the space is effectively used and the device configuration is simplified. It also reduces power loss. In addition, since the ground body functions as a shield, the effect of reducing interference with an external circuit can be obtained.

According to the third aspect, since the space inside the ground body is shielded by the shielding lid, the shielding effect in the second aspect is improved.

Further, according to claim 4, since the antenna according to claim 1 is mounted on a moving body such as an automobile,
For example, the GPS can preferably receive radio waves from a satellite with a low elevation angle, which makes it difficult to perform positioning by the GPS.

[Brief description of drawings]

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

2 (a) is a DD sectional view of this embodiment, FIG.
(B) is a longitudinal sectional view taken along a plane perpendicular to FIG. 1.

FIG. 3 (a) is a sectional view taken along line CC of this embodiment.
FIG. 3B is a mounting state diagram of the preamplifier section, and FIG. 3C is a BB sectional view.

FIG. 4 is a schematic configuration diagram of a GPS using this embodiment.

FIG. 5 (a) is a partial vertical cross-sectional view showing the configuration of a main part of a microstrip antenna according to a second embodiment of the present invention,
FIG. 5B is a partial vertical cross-sectional view showing the configuration of the main part of the microstrip antenna according to the third embodiment of the present invention.

6 (a) to 6 (f) are perspective views each showing an example of the shape and structure of an element that can be used in the present invention, and FIG. 6 (a) is a conventional circular element having a degenerate separation element. 6 (b) and 6 (f) are circular elements having degenerate separation elements and matching elements, FIGS. 6 (c) and 6 (d) are square elements having degenerate separation elements and matching elements, and FIG. FIG. 3A is a diagram showing a rectangular element having a matching element.

FIG. 7 (a) is a diagram showing the configuration of a printed cross dipole antenna according to a fourth embodiment of the present invention, and FIG. 7 (b) is a diagram showing the configuration of a cross slot antenna according to the fifth embodiment of the present invention. 7 (c) is a configuration of a short helical antenna according to a sixth embodiment of the present invention, FIG. 7 (d) is a configuration of a planar spiral antenna according to the seventh embodiment of the present invention, and FIG. The configuration of the ring patch antenna according to the eighth embodiment of the invention is
It is a perspective view or a sectional view showing respectively.

[Explanation of symbols]

 12, 60, 74 Microstrip antenna element 14 Preamplifier section 20 Reception section 26 Display control section 28 Microstrip antenna 30 Display unit 32 Power supply section 34 Reception processing section 40, 56, 58, 82 Ground body 62 Dielectric substrate 64 Radiation conductor 66 Ground conductor 68 Degenerate separation element 70 Feed point 78 Cross dipole 80 Reflector 84 Cross slot

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroya Suzuki 5-1-1 Shimorenjaku, Mitaka-shi, Tokyo Within Japan Radio Co., Ltd. (72) Inventor Shinpei 5-1-1 1-1 Shimorenjaku, Mitaka-shi, Tokyo Japan Radio Within the corporation

Claims (4)

[Claims] 1. An antenna, comprising: a substantially flat plate-shaped antenna element having a ground conductor; and a conductive ground body extending from the ground conductor of the antenna element to the side opposite to the antenna element. 2. The antenna according to claim 1, wherein a circuit for processing a signal related to the antenna element is arranged in a space inside a ground body. 3. The antenna according to claim 2, further comprising a shield lid that shields an inner space of the ground body. 4. The antenna according to any one of claims 1 to 3, which is used in a device for transmitting and / or receiving radio waves between a mobile body such as an automobile and a satellite.