JP3889886B2 - Microstrip antenna and portable wireless device including microstrip antenna - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microstrip antenna suitable for being mounted on a portable wireless device.
[0002]
[Prior art]
Various satellite communication systems for mobile communication have been proposed. There are two types of satellite communication systems: stationary mobile satellite communication systems that use geostationary satellites and non-stationary mobile satellite communication systems that use nonstationary satellites. .
Non-stationary mobile satellite communication systems include systems that use satellites with low and medium altitude orbits, systems that use satellites with long elliptical orbits, and systems that use tilt-synchronous orbits. Among these systems, there is a LEO (Low Earth Orbit) communication system as a system using non-geostationary satellites in low and medium altitude orbits. Since this LEO communication system has a small propagation delay time and a small propagation loss, it has the advantage that the transmission power of the terminal can be reduced and the terminal can be easily reduced in size and weight.
[0003]
Further, the LEO communication system includes a small-scale LEO (Little LEO) that handles only data transmission and a large-scale LEO (Big LEO) that can perform voice transmission. Among the large-scale LEOs is the international personal satellite communication system “Iridium” which is being promoted by the US company Iridium. This Iridium system is a TDMA (Time Division Multiple Access) system using a frequency of 1.6 GHz band, and (66 + 6) non-booths launched at a high altitude of 780 km to cover the entire earth. Communication is made using geostationary satellites. Non-geostationary satellites are arranged at 30 degree longitude intervals. In addition, the Iridium system is assigned a frequency bandwidth of 161.35 to 1626.5 MHz.
[0004]
In this Iridium system, although many satellites are required, the communication delay time can be ignored, so that communication such as voice and data can be performed in real time. Further, since the transmission power of the terminal can be reduced, the terminal can be portable. Therefore, if a portable wireless device for the Iridium system is carried, it becomes possible to perform telephone calls and data transmission in real time with telephones and mobile phones all over the world. In the iridium system, circularly polarized waves (right-handed) are used so as to be suitable for portable radio devices.
[0005]
In such a portable wireless device, a helical antenna or a microstrip antenna is used because it is necessary to receive circularly polarized waves.
Here, the configuration of a conventional microstrip antenna capable of transmitting and receiving circularly polarized waves is shown in FIG. 7A is a plan view of a rectangular microstrip antenna, FIG. 7B is a side view thereof, and FIG. 7C is a back view thereof.
A rectangular microstrip antenna 100 shown in FIGS. 7A to 7C has a rectangular patch-shaped rectangular radiating conductor 111 formed on the surface of a cylindrical dielectric substrate 110 having a predetermined thickness. An earth conductor 113 is formed on the surface. The rectangular radiating conductor 111 is provided with a feeding point 112 at a position deviated from the center in order to transmit and receive circularly polarized waves. The insertion point 110 a penetrates the dielectric substrate 110 at the position of the feeding point 112. Is provided.
[0006]
A coaxial cable 114, which is a semi-rigid cable, is attached to the back surface of the dielectric substrate 110. The central conductor 114a of the coaxial cable 114 is inserted into the insertion hole 110a, and the tip thereof is soldered to the feeding point 112. Has been. The shield conductor 114b of the coaxial cable 114 is electrically and mechanically fixed to the ground conductor 113 by soldering or the like.
Thus, since the coaxial cable 114 is derived from the position of the feeding point 112, it is derived eccentrically from the center of the dielectric substrate 110 as shown in FIG. 7B. Then, the circularly polarized wave received by the rectangular radiation conductor 111 is guided to the receiver via the coaxial cable 114, and the RF signal supplied from the coaxial cable 114 is radiated from the square radiation conductor 111 to the space as a circularly polarized electromagnetic wave. Will come to be.
[0007]
[Problems to be solved by the invention]
When the conventional microstrip antenna shown in FIG. 7 is mounted on a portable wireless device, the microstrip antenna is usually housed and mounted in a cover case that protects the microstrip antenna. However, in the conventional microstrip antenna shown in FIG. 7, since the coaxial cable 114 is led out of the center, the cover case for housing the antenna is eccentric in the portion for housing the coaxial cable 114 and is rotationally symmetric. It will not be a shape. For this reason, there is a problem in that handling is inconvenient because the aesthetic appearance is impaired and the size of the portion protruding left and right is different. In particular, when the cover case for storing the antenna is provided so as to be extendable and retractable with respect to the casing of the portable wireless device, there is a problem in that the cover case must be positioned and stored when stored.
[0008]
Therefore, an object of the present invention is to provide a microstrip antenna that can be housed in a cover case having a rotationally symmetric shape.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a microstrip antenna of the present invention includes a dielectric substrate in which a patch-like radiation conductor that radiates circularly polarized waves is formed on one surface and an earth conductor is formed on the other surface, and the dielectric A feed cable led out from substantially the center of the other surface of the substrate, an insertion hole formed in the dielectric substrate immediately below the feed point where the radiation conductor is eccentric, and the dielectric connected to the insertion hole A central conductor of the power supply cable is connected to the power supply point of the radiation conductor through a slit formed in the body substrate.
In the microstrip antenna, the dielectric substrate from which the feeding cable is led may be housed in an antenna cover case that is rotationally symmetric.
[0010]
Furthermore, a portable wireless device including the microstrip antenna of the present invention includes a dielectric substrate in which a patch-like radiation conductor that radiates circularly polarized waves is formed on one surface and a ground conductor is formed on the other surface, and the dielectric substrate A feed cable led from substantially the center of the other surface, an insertion hole formed in the dielectric substrate immediately below the feed point where the radiation conductor is eccentric, and the dielectric connected to the insertion hole A microstrip antenna in which a central conductor of the power supply cable is connected to the power supply point of the radiation conductor via a slit formed in a substrate is housed in an antenna cover case having a rotationally symmetric shape, The antenna cover case is provided in the housing so as to be extendable and contractible.
[0011]
According to the present invention, since the slit capable of inserting the central conductor of the coaxial cable is provided in the dielectric substrate, the coaxial cable can be drawn out from the center of the dielectric substrate. Thereby, the microstrip antenna can be configured to be rotationally symmetric. Therefore, since the cover case for housing the microstrip antenna can be formed in a rotationally symmetric shape, the aesthetic appearance is not impaired and the handling can be facilitated.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
One structural example of an embodiment of the microstrip antenna of the present invention is shown in FIG. FIG. 1A is a plan view of a rectangular microstrip antenna 1 of the present invention capable of transmitting and receiving circularly polarized waves, FIG. 1B is a side sectional view, and FIG. 1C is a rear view. .
In the rectangular microstrip antenna 1 shown in FIGS. 1A to 1C, a rectangular radiating conductor 11 having a rectangular patch shape is provided on the surface of a dielectric substrate 10 made of ceramic or the like having a cylindrical shape with a predetermined thickness. A thin-film ground conductor 13 is provided on the entire back surface of the back surface. The rectangular radiation conductor 11 and the ground conductor 13 are formed by vapor deposition on the dielectric substrate 10, or are formed by sticking a metal thin plate. In order to transmit and receive circularly polarized waves, the rectangular radiation conductor 11 is provided with a feeding point 12 at a position eccentric from the center. The feeding point 12 communicates with a slit 10b formed in the dielectric substrate 10. Thus, an insertion hole 10a is provided.
[0013]
The sectional shape of the slit 10b is rectangular, and is formed in the dielectric substrate 10 with a width from the feeding point 12 to the approximate center of the dielectric substrate 10. The thickness of the slit 10b is shown in FIG. As shown, it is formed as thin as possible.
A coaxial cable 14, which is a semi-rigid cable, is attached to the back surface of the dielectric substrate 10, and the central conductor 14 a of the coaxial cable 14 is inserted into the slit 10 b from the lower end of the slit 10 b and communicates with the slit 10 b. It is inserted into the insertion hole 10a. Then, the tip of the central conductor 14 a inserted through the insertion hole 10 a is soldered to the feeding point 12, and the rectangular radiation conductor 11 is fed by the coaxial cable 14. Further, the tip of the pipe-shaped shield conductor 14b of the coaxial cable 14 is electrically and mechanically fixed to the substantial center of the ground conductor 13 by soldering or the like.
[0014]
Thus, since the tip of the pipe-shaped shield conductor 14b of the coaxial cable 14 is fixed to the approximate center of the dielectric substrate 10, the center conductor 14a of the coaxial cable 14 is placed in the slit 10b as shown in FIG. Is inserted diagonally. Thereby, even if the feeding point 12 is eccentric, the coaxial cable 14 is led out from a substantially central position of the dielectric substrate 10. The rectangular microstrip antenna 1 configured as described above has a rotationally symmetric shape.
The circularly polarized wave received by the rectangular radiating conductor 11 is guided to the receiver via the coaxial cable 14, and the RF signal supplied from the coaxial cable 14 is radiated from the rectangular radiating conductor 11 to the space as a circularly polarized electromagnetic wave. Will come to be.
In addition, the width | variety of the slit 10b should just be a width | variety which the center conductor 14a of the coaxial cable 14 can penetrate.
[0015]
Next, the 2nd structural example of embodiment of the microstrip antenna of this invention is shown in FIG. FIG. 2A is a plan view of a circular microstrip antenna 2 of the present invention capable of transmitting and receiving circularly polarized waves, FIG. 2B is a cross-sectional view of the side surface, and FIG. .
In the circular microstrip antenna 2 shown in FIGS. 2A to 2C, a circular radiating conductor 21 having a circular patch shape is provided on the surface of a dielectric substrate 20 made of ceramic or the like having a cylindrical shape with a predetermined thickness. A thin-film ground conductor 23 is provided on the entire back surface of the back surface. The circular radiating conductor 21 and the ground conductor 23 are formed by vapor deposition on the dielectric substrate 20, or are formed by sticking a metal thin plate. In order to transmit and receive circularly polarized waves, the circular radiating conductor 21 has opposite edges cut out, and a feeding point 22 is provided at a position eccentric from the center. An insertion hole 20 a is provided so as to communicate with the slit 20 b formed in the body substrate 20.
[0016]
The sectional shape of the slit 20b is rectangular, and is formed in the dielectric substrate 20 with a width from the feeding point 22 to the approximate center of the dielectric substrate 20. The thickness of the slit 20b is shown in FIG. As shown, it is formed as thin as possible.
A coaxial cable 24, which is a semi-rigid cable, is attached to the back surface of the dielectric substrate 20, and the central conductor 24a of the coaxial cable 24 is inserted into the slit 20b from the lower end of the slit 20b and communicates with the slit 20b. It is inserted into the insertion hole 20a. Then, the tip of the center conductor 24 a inserted through the insertion hole 20 a is soldered to the feeding point 22, and the circular radiation conductor 21 is fed by the coaxial cable 24. Further, the tip of the pipe-shaped shield conductor 24b of the coaxial cable 24 is electrically and mechanically fixed to the substantial center of the ground conductor 23 by soldering or the like.
[0017]
Thus, since the tip of the pipe-shaped shield conductor 24b of the coaxial cable 24 is fixed to the approximate center of the dielectric substrate 20, the center conductor 24a of the coaxial cable 24 is placed in the slit 20b as shown in FIG. Is inserted diagonally. As a result, even if the feeding point 22 is eccentric, the coaxial cable 24 is led out from the approximate center position of the dielectric substrate 20. The thus configured circular microstrip antenna 2 has a rotationally symmetric shape.
The circularly polarized wave received by the circular radiating conductor 21 is guided to the receiver via the coaxial cable 24, and the RF signal supplied from the coaxial cable 24 is radiated from the circular radiating conductor 21 to the space as a circularly polarized electromagnetic wave. Will come to be.
In addition, the width | variety of the slit 20b should just be a width | variety which the center conductor 24a of the coaxial cable 24 can penetrate.
[0018]
The cross-sectional shapes of the slits 10b and 20b described with reference to FIGS. 1 and 2 are rectangular, but the shape of the slits in the microstrip antenna of the present invention may be the shapes shown in FIGS.
FIGS. 3A to 3C show the shape of the second slit. FIG. 3A is a plan view, FIG. 3B is a side sectional view, and FIG. 3C is a back view. . The shape of the slit 31b shown in these drawings is a wedge shape whose width is narrowed toward the top, and the upper end thereof is an insertion hole 31a. The position of the insertion hole 31 a is the position of the feeding point of the radiation conductor formed on the surface of the dielectric substrate 31. Further, the width of the lower end of the slit 31b formed on the back surface of the dielectric substrate 31 is a width between the feeding point and the approximate center of the dielectric substrate 31 as shown in FIG.
[0019]
Next, FIGS. 4A to 4C show the shape of the third slit. FIG. 4A is a plan view, FIG. 4B is a side sectional view, and FIG. FIG. The shape of the slit 32a shown in these drawings is a wedge shape whose width increases toward the top, and its lower end is an insertion hole 32b for inserting the central conductor of the coaxial cable. The position of the insertion hole 32 b formed in the back surface of the dielectric substrate 32 is set at a substantially central position of the dielectric substrate 32. The width of the upper end of the slit 32a formed on the surface of the dielectric substrate 31 is such that the feed point of the radiation conductor formed on the surface of the dielectric substrate 32 and the dielectric substrate 32 are as shown in FIG. The width is approximately the center.
In the above description, the dielectric substrate is described as being made of ceramic. However, the present invention is not limited to this and may be a dielectric substrate made of a general dielectric material having a predetermined dielectric constant.
[0020]
Next, FIG. 5 and FIG. 6 show a configuration example of a portable wireless device in which the microstrip antenna according to the present invention is applied to an iridium system or the like. 5A is a plan view of the portable wireless device partially shown in cross-sectional view, FIG. 5B is a side view of the portable wireless device, and FIG. 5C is a portable wireless device partially shown in cross-sectional view. FIG. 6 is a plan view showing a portable wireless device containing an antenna unit.
5A to 5C, a transmission / reception circuit is housed in a housing 40a of the portable wireless device 40. The housing 40a has a display unit 40b for performing various displays, and dialing and various operations. A plurality of buttons 40c to perform are provided. An antenna portion 41 is provided to be extendable and contractable with respect to the housing 40a. FIG. 6 shows a state where the antenna unit 41 is housed in the housing 40a.
[0021]
The antenna unit 41 includes a microstrip antenna 42, an upper antenna cover case 41a that houses the microstrip antenna 42, and a lower antenna cover case 41b. The microstrip antenna 42 is a microstrip antenna having the configuration shown in FIG. 1 or FIG. The upper antenna cover case 41a accommodates a dielectric substrate in a microstrip antenna, and the lower antenna cover case 41b accommodates a coaxial cable. The upper antenna cover case 41a and the lower antenna cover case 41b are made of synthetic resin and have a rotationally symmetric shape.
[0022]
In the portable wireless device 40 having such a configuration, since the microstrip antenna 42 is provided on the upper portion of the antenna unit 41, transmission / reception can be performed regardless of whether the antenna unit 41 is in the extended state or the stored state. Further, when the portable wireless device 40 is on standby, the antenna unit 41 can be housed in the housing 40a as shown in FIG.
Note that the antenna unit 41 may be tiltable with respect to the housing 40a when the antenna unit 41 that can be expanded and contracted with respect to the housing 40a is extended.
[0023]
【The invention's effect】
As described above, the microstrip antenna of the present invention is provided with the slit through which the central conductor of the coaxial cable can be inserted in the dielectric substrate, so that the coaxial cable can be drawn out from the center of the dielectric substrate. Can do. Thereby, a microstrip antenna can be made into a rotationally symmetric shape. Therefore, since the cover case that accommodates the microstrip antenna can be formed in a rotationally symmetric shape, the appearance of the cover case when attached to the portable wireless device is not impaired, and the handling is facilitated.
[Brief description of the drawings]
FIG. 1 is a diagram showing a first configuration example of an embodiment of a microstrip antenna of the present invention.
FIG. 2 is a diagram showing a second configuration example of an embodiment of a microstrip antenna of the present invention.
FIG. 3 is a diagram showing a second configuration example of slits in the microstrip antenna according to the embodiment of the present invention.
FIG. 4 is a diagram showing a third configuration example of slits in the microstrip antenna according to the embodiment of the present invention.
FIG. 5 is a diagram showing a configuration in which a microstrip antenna according to an embodiment of the present invention is attached to a portable wireless device.
FIG. 6 is a diagram illustrating a state in which the antenna unit is housed when the microstrip antenna according to the embodiment of the present invention is attached to the portable wireless device.
FIG. 7 is a diagram showing a configuration of a conventional microstrip antenna.
[Explanation of symbols]
1,100 rectangular microstrip antenna 2 circular microstrip antennas 10, 20, 31, 32 dielectric substrates 10a, 20a, 31a, 32b, 110a insertion holes 10b, 20b, 31b, 32a slits 11, 111 rectangular radiating conductors 12, 22 , 112 Feed point 13, 23, 113 Ground conductors 14, 24, 114 Coaxial cables 14a, 24a, 114a Center conductors 14b, 24b, 114b Shield conductor 21 Circular radiating conductor 40 Portable radio 40a Housing 40b Display unit 40c Button 41 Antenna Part 41a upper antenna cover case 41b lower antenna cover case 42 microstrip antenna

Claims (3)

A dielectric substrate in which a patch-like radiation conductor that radiates circularly polarized waves is formed on one surface, and a ground conductor is formed on the other surface;
A power supply cable derived from the approximate center of the other surface of the dielectric substrate,
A central conductor of the feeder cable through an insertion hole formed in the dielectric substrate immediately below the feeding point where the radiation conductor is eccentric, and a slit formed in the dielectric substrate in communication with the insertion hole Is connected to the feed point of the radiating conductor. 2. The microstrip antenna according to claim 1, wherein the dielectric substrate from which the feeding cable is led is housed in an antenna cover case that is rotationally symmetric. A dielectric substrate in which a patch-like radiation conductor that radiates circularly polarized waves is formed on one surface and a ground conductor is formed on the other surface, and a power supply cable led out from the approximate center of the other surface of the dielectric substrate. An insertion hole formed in the dielectric substrate immediately below the eccentric feeding point of the radiation conductor, and a slit formed in the dielectric substrate in communication with the insertion hole. A microstrip antenna whose conductor is connected to the feeding point of the radiating conductor is housed in an antenna cover case having a rotationally symmetric shape, and the antenna cover case is provided in a housing in a telescopic manner. A portable wireless device including a microstrip antenna.

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