JPH0648209U - Circularly polarized antenna - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a circularly polarized antenna that is small and can be used in a wide range of temperature environments. [Structure] A flat spiral-wound antenna 52 is provided on the front surface of a high dielectric constant dielectric substrate 50, and a base plate 54 is provided on the back surface thereof.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a circularly polarized antenna which is small and can be used in a wide range of temperature environments.

[0002]

[Prior art]

 2. Description of the Related Art In recent years, GPS systems that receive information radiated from positioning satellites and calculate the position have been widely used by being incorporated in navigation systems for aircraft, ships, and vehicles. In addition, small portable receivers for mountain climbing and location confirmation at outdoor leisure are also provided.

In these vehicle-mounted and small-sized portable receivers, etc., signal processing circuits have been increasingly integrated and the circuits themselves have been miniaturized, but they receive information from positioning satellites. The actual size of the antenna has not been fully reduced.

The signal from the positioning satellite is transmitted by circular polarization, and there is an antenna using a patch antenna element shown in FIGS. 5 and 6 as an example of the antenna of the receiving device. To briefly explain this, a patch antenna element 18 having a patch 16 laminated on a dielectric substrate 14 is arranged on the surface of a low noise amplifier case 12 accommodating the low noise amplifier 10. The patch antenna element 18 is connected to the radome 20. Covered with. The feed point 22 of the patch antenna element 18 and the low noise amplifier 10 are connected by a coaxial line 24.

The dimension of the long side of the patch antenna element 18 becomes short according to the dielectric constant εγ of the dielectric substrate 14, and is suitable for downsizing. However, the patch antenna element 18 is a resonance type and has a relatively narrow band. Then, as the dielectric constant ε γ of the dielectric substrate 14 changes with temperature, the resonance frequency changes. For this reason, it is not practical as an antenna used in a wide range of temperature environments such as those used in vehicles.

Therefore, although miniaturization is not sufficient, a planar spiral-wound antenna shown in FIG. 7 and a helical antenna shown in FIG. 8 have been put into practical use as those that can be used in a wide range of temperature environments. .

In the antenna shown in FIG. 7, a flat spiral-wound antenna 30 having a maximum outer diameter of about 0.3λ (where λ is a wavelength of a reception frequency) is supported by a shaft portion 32 at a feeding point of a central axis, and a flat spiral coil is provided. A ground plate 34 is arranged at a distance of about 0.15λ to 0.25λ from the winding antenna 30. Here, in order to set the half-value angle of the radiation pattern wide, the distance between the planar spiral-wound antenna 30 and the ground plane 34 is set. The base plate 34 also serves as the surface of the low noise amplifier case 12.

The antenna shown in FIG. 8 uses a helical antenna 40 having a maximum outer diameter of about 0.3λ and an axial height from the ground plane 34 of 0.3λ to 0.8λ.

[0009]

[Problems to be solved by the device]

 In the case of using the above-described conventional planar spiral antenna 30 or helical antenna 40, the antenna itself has an outer diameter of about 57 mm with respect to the signal of 1.57542 GHz transmitted from the positioning satellite. The height of FIG. 7 is 28.5 mm to 47.5 mm, and the height of FIG. 8 is 57 mm to 152 mm, which is relatively large. Therefore, there has been a strong demand for the realization of a circularly polarized antenna which can be used in a wide range of temperature environments and which can be easily downsized.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a circularly polarized antenna that can be used in a wide range of temperature environments and that is easily miniaturized.

[0011]

[Means for Solving the Problems]

 In order to achieve such an object, the circularly polarized wave antenna of the present invention is constructed by disposing a flat spiral-wound antenna on the surface of a high-dielectric-constant dielectric substrate and disposing a ground plate on the back surface of the dielectric substrate. Has been done.

Then, a hole is formed on the axis of the planar spiral antenna of the dielectric substrate, and a matching circuit connected to the feeding point of the planar spiral antenna is arranged in the hole. You can do it.

Further, a low noise amplifier case accommodating a low noise amplifier may be disposed and fixed on the back surface side of the dielectric substrate, and the low noise amplifier and the matching circuit may be connected.

Further, the base plate of the dielectric substrate and the base plate of the print substrate on which the low noise amplifier is formed may be attached back to back.

[0015]

[Work]

 Since the flat spiral antenna is arranged on the surface of the high dielectric constant dielectric substrate, the wavelength is shortened by the dielectric, and the outer diameter of the flat spiral antenna can be reduced. Further, since the ground plane is arranged on the back surface of the dielectric substrate, the distance between the plane spiral-wound antenna and the ground plane necessary to obtain a desired radiation pattern having a wide half-value angle can be shortened. Therefore, it is easy to downsize the whole antenna.

If a matching circuit is provided in the hole formed in the dielectric substrate, a desired output impedance can be obtained without increasing the thickness.

Further, if the dielectric substrate on which the flat spiral-wound antenna is arranged is fixed to the low noise amplifier case, the entire circular polarization antenna including the antenna unit and the amplifier unit is integrated, and its handling becomes easy. .

Further, if the ground plane of the dielectric substrate and the ground plane of the printed circuit board on which the low noise amplifier is formed are attached back to back, the height of the entire circularly polarized antenna can be made small.

[0019]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. 1 is a vertical cross-sectional view of an embodiment of the circularly polarized antenna of the present invention, FIG. 2 is a plan view of an example of a flat spiral antenna, and FIG. 3 is a circularly polarized antenna of FIG. It is a partially exploded perspective view of FIG.

In FIG. 1 to FIG. 3, a planar spiral-wound antenna 52 is appropriately arranged by printing or vapor deposition on the surface of a disk-shaped dielectric substrate 50 having a high dielectric constant of 10 or more. . On the back surface of the dielectric substrate 50, similarly, a base plate 54 is appropriately arranged by printing or vapor deposition. Further, the dielectric substrate 50 is provided with a bottomed hole 56 from the back surface at the axial center of the planar spiral-wound antenna 52, and a small through hole 58 is drilled at the bottom thereof at the axial center. A matching circuit 64 including a coil 60 and a capacitor 62 is housed in the bottomed hole 56.

Further, the dielectric substrate 50 is fixed to the bottom surface of the low noise amplifier case 12 in the shape of a flat cylindrical container by adhering the ground plate 54 thereto, and the radome 20 is covered with the dielectric substrate 50. It is arranged in the case 12. A printed circuit board 66 on which the low noise amplifier 10 is formed is fixed to the low noise amplifier case 12 by attaching a base plate 68 to the bottom surface of the case 12. Further, the lid body 70 closes the low noise amplifier case 12.

The matching circuit 64 has one end of the coil 60 fixedly connected to the feed point of the axial center of the flat spiral antenna 52 by soldering or the like. The other end of the coil 60 is connected to the input terminal of the low noise amplifier 10 and also connected to the ground plate 54 via the capacitor 62. In this matching circuit 64, a constant is set so that the output impedance is 50Ω when the planar spiral-wound antenna 52 is viewed from the other end of the coil 60.

In such a configuration, by using the dielectric substrate 50 having a dielectric constant εγ of 10, the flat spiral-wound antenna 52 can have a small outer diameter of about 35 mm. Further, the thickness of the dielectric substrate 50 itself can be about 11 mm. Therefore, by making the low-noise amplifier case 12 as thin as possible, the circularly polarized antenna of the present invention can be made extremely small as a whole with an outer diameter of about 38 mm and a height of about 19 mm. However, the planar spiral-wound antenna 52 has a wide band rather than a resonance type, and according to experiments by the inventor, a gain which can be sufficiently used in a wide temperature environment of -40 ° C to 80 ° C was obtained. .

The flat spiral antenna 52 generally has an output impedance of 150 to 170Ω, but by setting the output impedance to 50Ω by the matching circuit 64, the dielectric substrate 50 and the flat spiral antenna 52 can be connected to each other. The characteristic inspection of the antenna unit including the ground plane 54 and the matching circuit 64 can be performed by a general antenna measuring device, which is convenient for mass production. In addition, since the matching circuit 64 is housed within the thickness of the dielectric substrate 50, the thickness does not increase excessively and the miniaturization is not hindered.

Further, since the dielectric substrate 50 is fixedly attached to the surface of the low-noise amplifier case 12 by contact, the antenna unit and the amplifier unit are integrated, and the whole antenna is one flat disc shape, which is easy to handle. Besides, it is extremely suitable for fixing to a vehicle body or the like.

FIG. 4 is a vertical sectional view showing another embodiment of the circularly polarized antenna of the present invention. In FIG. 4, the same members as those in FIG. 1 are designated by the same reference numerals, and duplicate description will be omitted.

4 is different from FIG. 1 in that there is no bottom portion of the low noise amplifier case 12 ′, and there is a bottom plate 54 of the dielectric substrate 50 and a bottom plate 68 of a print substrate 66 on which the low noise amplifier 10 is formed. However, it is being directly contacted.

In such a configuration, the height of the circularly polarized antenna as a whole can be reduced by the thickness of the bottom portion of the low noise amplifier case 12 in FIG. 1, and the size can be further reduced.

In the above description, the circularly polarized antenna of the present invention has been described as an antenna used to receive signals from positioning satellites, but the present invention is not limited to this, and the planar antenna may be used depending on the signal frequency to be transmitted and received. It can be easily understood that the outer diameter of the spiral antenna 52 can be changed appropriately and the thickness of the dielectric substrate 50 can be set appropriately according to a desired radiation pattern.

[0030]

[Effect of device]

 As described above, since the circularly polarized antenna of the present invention is constructed, it has the following special effects.

In the circularly polarized wave antenna according to claim 1, since the flat spiral antenna and the base plate are arranged on the dielectric substrate having a high dielectric constant, the outer diameter of the antenna is reduced by the amount corresponding to the shortened wavelength. The size can be reduced, and both the outer diameter and the height can be reduced to approximately 1/2 as compared with those using the conventional planar spiral-wound antenna, which is extremely compact. Moreover, due to the wide band characteristics of the flat spiral-wound antenna, it can withstand practical use in a wide range of temperature environments.

Further, in the circularly polarized wave antenna according to claim 2, the matching circuit is incorporated within the thickness of the dielectric substrate, and the desired output impedance as an antenna unit is obtained without increasing the thickness. can get. Therefore, by setting the output impedance to 50 Ω, the characteristics of the antenna unit can be inspected with general-purpose measuring equipment, and the antenna related to the present invention can be used in a line for performing inspection of a general antenna with an output impedance of about 50 Ω. The unit can be inspected, which is convenient for mass production.

Further, in the circularly polarized antenna according to the third aspect, the antenna unit and the amplifier unit are integrated into a flat disc shape as a whole, and the handling thereof is easy. In particular, it is suitable when it is fixed to the top plate of the vehicle body using a magnet or the like.

Further, in the circularly polarized wave antenna according to the fourth aspect, the dielectric substrate and the base plate of the printed circuit board are attached back to back, so that the thickness can be further reduced. In particular, when it is fixed to the vehicle body, the air resistance is reduced due to the thinner thickness, and wind noise is less likely to occur.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a circularly polarized antenna of the present invention.

FIG. 2 is a plan view of an example of a flat spiral antenna.

3 is a partially exploded perspective view of the circularly polarized antenna of FIG.

FIG. 4 is a vertical sectional view showing another embodiment of the circularly polarized antenna of the present invention.

FIG. 5 is a vertical cross-sectional view of a circular polarization antenna using a conventional patch antenna element.

FIG. 6 is a plan view of a patch antenna element.

FIG. 7 is a vertical cross-sectional view of a circularly polarized antenna using a conventional flat spiral antenna.

FIG. 8 is a vertical cross-sectional view of a circular polarization antenna using a conventional helical antenna.

[Explanation of symbols]

 10 Low Noise Amplifier 12, 12 'Low Noise Amplifier Case 50 Dielectric Substrate 52 Flat Spiral Antenna 54 Ground Plate 56 Bottom Hole 64 Matching Circuit 66 Printed Circuit Board 68 Ground Plate

Claims (4)

[Scope of utility model registration request] 1. A circularly polarized antenna comprising a high-dielectric-constant dielectric substrate on which a flat spiral-wound antenna is disposed, and a bottom plate disposed on the rear surface of the dielectric substrate. 2. The circularly polarized antenna according to claim 1, wherein a hole is formed in the dielectric substrate on the axis of the planar spiral antenna, and the hole is connected to a feeding point of the planar spiral antenna. A circularly polarized wave antenna comprising a matching circuit provided therein. 3. The circularly polarized antenna according to claim 2, wherein a low noise amplifier case for accommodating a low noise amplifier is arranged and fixed on the back surface side of the dielectric substrate,
A circular polarization antenna, characterized in that the low noise amplifier and the matching circuit are connected to each other. 4. The circularly polarized antenna according to claim 3, wherein the ground plane of the dielectric substrate and the ground plane of the printed circuit board on which the low noise amplifier is formed are attached back to back. Circular polarized antenna.