JP2013078027A - Patch antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a patch antenna which is easily manufactured and has small variations of antenna characteristics.SOLUTION: A patch antenna 1 includes: a substrate 10 made of a dielectric body; a patch electrode 11 formed on an upper surface 10a of the substrate 10; a feeding electrode 13 which is formed at a part of a bottom surface 10b of the substrate 10 and is capacitively coupled to the patch electrode 11; and a ground electrode which is formed at the bottom surface 10b of the substrate 10 and is electrically insulated from the feeding electrode 13. Since all side surfaces 10c to 10f of the substrate are insulation surfaces that no electrode pattern exists, the patch antenna prevents variations of antenna characteristics due to misalignment of a side surface electrode pattern.

Description

  The present invention relates to a patch antenna, and more particularly to an electrode structure of a patch antenna.

  In recent years, location information services using a GPS system are rapidly expanding. A microstrip antenna called a “patch antenna” is used as the GPS antenna. In the conventional patch antenna, a radiation electrode (patch electrode) and a ground electrode are formed on the top and bottom surfaces of a substantially square dielectric substrate, respectively, and a feed pin penetrating the dielectric substrate is provided near the center of the dielectric substrate. A structure in which power is supplied to a patch electrode via a power supply pin is common (see, for example, Patent Document 1).

  However, in the case of a patch antenna using a feed pin, the feed pin is necessary, and a through hole for inserting the feed pin needs to be formed in the dielectric substrate in advance, and the feed pin is further soldered A process is also required, and there is a problem that the manufacturing cost increases. Further, when the patch antenna is mounted on the printed circuit board, it is necessary to solder-connect the tip end portion of the power supply pin to the power supply line on the printed circuit board side, and there is a problem that the reflow mounting process cannot be adopted. Furthermore, the upper end (head) of the power feed pin protrudes above the electrode surface of the radiation electrode, and when the power feed pin head is soldered to the patch electrode surface, the height further increases. There is a problem that a reduction in the height of the antenna is hindered.

  Therefore, a patch antenna that does not use a feed pin has also been proposed. For example, the patch antenna described in Patent Document 2 has a power supply line provided on the side surface of a dielectric substrate, and power is supplied to the patch electrode through this power supply line. Further, the patch antenna described in Patent Document 3 has a concave portion formed on the side surface of the dielectric substrate, a power supply terminal (power supply line) is provided in the concave portion, a power supply conductor is provided on the top surface of the dielectric substrate, and a patch electrode. In this case, capacitively coupled power supply is performed.

JP 2003-289219 A JP 2002-314325 A JP 2001-267834 A

  However, the conventional patch antennas described in Patent Documents 2 and 3 require a step of printing an electrode pattern on the side surface separately from the upper and lower surfaces of the dielectric substrate, and the manufacturing cost increases due to an increase in man-hours. There's a problem. In addition, it is difficult to print an electrode pattern on a part of the side surface of a thin dielectric substrate of about several millimeters with high positional accuracy, and there is a problem that antenna characteristics deteriorate when the position of the electrode is shifted.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a patch antenna that can be manufactured with a small number of man-hours, has small variations in antenna characteristics, and has a low profile.

  In order to solve the above problems, a patch antenna according to the present invention includes a dielectric substrate, a patch electrode formed on an upper surface of the substrate, a part of a bottom surface of the substrate, the patch electrode and an electromagnetic field. And a ground electrode formed on the bottom surface of the substrate and insulated from the power supply electrode, wherein all side surfaces of the substrate are insulating surfaces having no electrode pattern.

  According to the present invention, there is no need to print an electrode pattern on the side surface of the substrate, the manufacturing cost can be reduced, and there is no variation in antenna characteristics due to electrode displacement. In addition, since no power supply pin is used, there is no need for drilling the board or soldering the power supply pin, and reflow mounting can be employed.

  In the present invention, one side of the power supply electrode is provided in the center in the width direction in contact with the edge of the substrate, and the other three sides are opposed to the ground electrode through an insulating gap having a predetermined width. Is preferred. According to this configuration, it is possible to realize a patch antenna with good characteristics that is hardly affected by noise.

  The patch antenna according to the present invention preferably further comprises corner electrodes formed at the four corners of the bottom surface of the substrate and insulated and separated from the ground electrode, and a chip element is connected to the corner electrode. In this case, it is preferable that the chip element includes two terminals, one terminal is connected to the corner electrode, and the other terminal is connected to the ground. According to this configuration, a chip element for adjusting impedance and frequency can be connected as necessary, and the characteristics of the patch antenna can be easily adjusted.

  According to the present invention, it is possible to provide a patch antenna that can be manufactured with a small number of man-hours, has small variations in antenna characteristics, and has a low profile.

FIG. 1 is a schematic perspective view showing the configuration of the patch antenna 1 according to the first embodiment of the present invention, and shows a state mounted on a printed circuit board 20. FIG. 2 is a development view of the patch antenna 1. FIG. 3 is a schematic perspective view showing an example of a conductor pattern in the antenna mounting area 20 </ b> A of the printed circuit board 20. FIG. 4 is a schematic perspective view showing another example of the conductor pattern in the antenna mounting area 20A of the printed circuit board 20. FIG. 5 is a schematic perspective view showing the configuration of the patch antenna 2 according to the second embodiment of the present invention, and shows a state before being mounted on the printed circuit board 20. FIG. 6 is a schematic plan view showing an example of a conductor pattern in the antenna mounting area 20A of the printed board 20 on which the patch antenna 2 is mounted.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic perspective view showing the configuration of the patch antenna 1 according to the first embodiment of the present invention, and shows a state mounted on a printed circuit board 20. FIG. 2 is a development view of the patch antenna 1.

  As shown in FIGS. 1 and 2, the patch antenna 1 includes a substrate 10, a patch electrode 11 formed on the upper surface 10 a of the substrate 10, a ground electrode 12 formed on the bottom surface 10 b of the substrate 10, and a ground electrode 12. In addition, a power supply electrode 13 formed on the bottom surface 10 b of the substrate 10 is provided.

  The substrate 10 is a thin dielectric block having an upper surface 10a and a bottom surface 10b as main surfaces. The planar size of the substrate 10 is preferably slightly larger than the planar size of the patch electrode 11 and is not particularly limited, but may be, for example, 12 × 12 (mm). The thickness of the substrate 10 is preferably as thick as possible from the viewpoint of antenna characteristics, but is preferably as thin as possible from the viewpoint of reducing the height, and is preferably 2 to 4 (mm). The material of the substrate 10 is ceramic, and has an appropriate dielectric constant in accordance with the resonance frequency of the patch antenna. By using a high dielectric constant ceramic as the substrate material, the wavelength shortening effect can be obtained, and the antenna can be miniaturized.

  The patch electrode 11 is a rectangular pattern with one side having a length of about ½ wavelength. The aspect ratio of the rectangular pattern is adjusted according to characteristics such as gain and bandwidth. The planar size of the patch electrode 11 can be set to 10 × 10 (mm), for example.

  The ground electrode 12 is formed on substantially the entire bottom surface 10 b excluding the power supply electrode 13. The ground electrode 12 is connected to the ground pattern on the printed circuit board 20 side.

  The feeding electrode 13 is an electrode connected to the feeding line. The power supply electrode 13 has a rectangular pattern and is provided in contact with the edge of one side of the bottom surface 10 b of the substrate 10. In addition, the feeding electrode 13 is disposed at the center of the bottom surface 10b of the substrate 10 in the width direction, thereby ensuring the symmetry of the electrode pattern. The power supply electrode 13 is connected to a power supply line 21 on the printed circuit board 20 side.

  One side of the power supply electrode 13 is in contact with the edge of one side of the bottom surface 10b of the substrate 10, but the other three sides are opposed to the ground electrode 12 through an insulating gap region 14 that is a region where no electrode pattern is formed. ing. Since the insulating gap region 14 having a constant width is interposed between the power supply electrode 13 and the ground electrode 12, the insulation between them can be ensured. In addition, since the three directions around the power supply electrode 13 are surrounded by the ground electrode 12, it can be made less susceptible to noise.

  In the present embodiment, the power supply electrode 13 is formed small in a region near the edge of one side of the bottom surface 10b, but may be an elongated rectangular pattern extending from the edge side of the bottom surface 10b toward the center. In this case, the portion overlapping the patch electrode 11 increases, so that capacitive coupling can be strengthened.

  Electrode patterns are not formed on the four side surfaces 10 c to 10 f of the substrate 10. For this reason, the patch electrode 11 is not directly connected to the power supply electrode 13 but is capacitively coupled through a gap (dielectric) corresponding to the thickness of the substrate 10. Thus, power can be supplied without going through the electrode pattern on the side surface of the substrate 10. As described above, the patch antenna 1 according to the present embodiment does not require an electrode printing process on the side surface of the substrate 10 because all the side surfaces 10c to 10f of the substrate 10 are insulating surfaces without an electrode pattern, and is easy and It can be manufactured at low cost. In addition, it is possible to prevent a decrease in antenna characteristics due to variations in the position of the electrode pattern formed on the side surface of the substrate.

  FIG. 3 is a schematic perspective view showing an example of a conductor pattern in the antenna mounting area 20 </ b> A of the printed circuit board 20.

  As shown in FIG. 3, a ground pad 22 and a power feeding pad 23 are provided in the antenna mounting region 20A. When the antenna is mounted, the ground pad 22 is connected to the ground electrode 12 of the patch antenna 1, and the power feeding pad 23 is connected to the power feeding electrode 13.

  A conductor layer and a resist layer are sequentially formed on the surface of the printed circuit board 20, and the conductor layer is covered with the resist layer, but there is a region not covered with the resist layer. The antenna mounting area 20 </ b> A is also one of the areas not covered with the resist layer, and the conductor layer in this area is exposed on the surface of the printed circuit board 20. The conductor layer includes a ground pattern and a feed line, the ground pad 22 is a part of the ground pattern exposed in the antenna mounting region 20A, and the feed pad 23 is exposed in the antenna mounting region 20A. It is the tip part. On the other hand, since the periphery of the antenna mounting area 20A is an area covered with the resist layer 24, the resist pattern and the feed line 21 outside the antenna mounting area 20A cannot be visually recognized. Therefore, the power supply line 21 covered with the resist layer 24 is represented by a broken line.

  FIG. 4 is a schematic perspective view showing another example of the conductor pattern in the antenna mounting area 20A of the printed circuit board 20.

  As shown in FIG. 4, the antenna mounting region 20 </ b> A is provided with eight divided ground pads 22 a to 22 h and a power feeding pad 23. These divided ground pads 22a to 22h can be formed by covering a substantially lattice-shaped dividing line with a resist layer. That is, although it is a divided pattern on the surface, it remains an integral conductor pattern internally. Thus, by making the exposed pattern of the ground pad a plurality of small patterns instead of one large pattern, the solder joint strength of the ground electrode 12 of the patch antenna 1 can be increased.

  FIG. 5 is a schematic perspective view showing the configuration of the patch antenna 2 according to the second embodiment of the present invention, and shows a state before being mounted on the printed circuit board 20.

  As shown in FIG. 5, the patch antenna 2 is characterized in that corner electrodes 15 a to 15 d are further provided at four corners of the bottom surface 10 b of the substrate 10. The corner electrodes 15 a to 15 d are electrodes that are insulated and separated from the ground electrode 12. For this reason, the ground electrodes at the positions where the corner electrodes 15a to 15d are formed are omitted. Since other configurations are substantially the same as those of the patch antenna 1 according to the first embodiment, the same reference numerals are given and detailed description thereof is omitted.

  FIG. 6 is a schematic plan view showing an example of a conductor pattern in the antenna mounting area 20A of the printed board 20 on which the patch antenna 2 is mounted.

  As shown in FIG. 6, lands 25a to 25d are provided at four corners of the antenna mounting area 20A on the printed board 20 on which the patch antenna 2 is mounted, corresponding to the corner electrodes 15a to 15d. Each of the lands 25a to 25d is surrounded by an insulating region and insulated and separated from the surrounding ground pattern. The main parts of the lands 25a to 25d are contained in the antenna mounting area 20A, but a part of the land 25a to 25d protrudes outside the antenna mounting area 20A. The protruding portion functions as a pad when mounting a chip element such as a chip capacitor or a chip inductor.

  As with the antenna mounting area 20A, the adjustment element mounting areas 20B to 20E are areas in which the resist layer is excluded, and the conductor layers are exposed. Specifically, a part of the lands 25a to 25d protruding from the antenna mounting area 20A and a part of the ground pattern are exposed. Here, a part of the lands 25a to 25d serves as a pad for soldering one terminal 31a of the chip element 30 having a two-terminal structure, and a part of the ground pattern is used for soldering the other terminal 31b. It becomes a pad. Then, the chip element 30 is mounted as shown in the figure as necessary, and functions as an impedance adjustment element or a frequency adjustment element of the patch antenna 2.

  As described above, since the patch antenna 2 according to the present embodiment is provided with the corner electrodes 15a to 15d at the four corners of the bottom surface 10b of the substrate 10, the chip element for adjusting the impedance and the frequency as necessary. 30 can be connected, and the antenna characteristics can be easily adjusted.

  The patch antennas 1 and 2 according to the above embodiment may be formed by forming electrodes on the upper and lower surfaces of a substrate previously formed in one size, and have a plurality of sizes (for example, four). A large substrate may be prepared, and electrodes may be formed on the upper and lower surfaces of the substrate, and then dicing into one size. Since the patch antennas 1 and 2 according to the above embodiment do not have electrodes on the side surfaces of the substrate, it is not necessary to perform metallization of the side surfaces after the division. Therefore, it is possible to easily perform a process of taking a large number of antenna chips from one large substrate.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  For example, although the case where the radiation electrode has a rectangular pattern has been described as an example in the above embodiment, the shape of the radiation electrode is not limited to the rectangular pattern, and may be another polygonal shape or a circular shape.

  In the above embodiment, the power supply electrode 13 is provided at the center in the width direction of the edge of the substrate 10. However, the power supply electrode 13 may be provided at a position shifted from the center.

DESCRIPTION OF SYMBOLS 1, 2 Patch antenna 10 Board | substrate 10a Base | substrate upper surface 10b Base | substrate bottom surface 10c-10f Side surface 11 Patch electrode 12 Ground electrode 13 Feed electrode 14 Insulation gap area | region 15a-15d Corner electrode 20 Printed circuit board 20A Antenna mounting area | region 20B-20E Adjustment Element mounting area 21 Power supply lines 22, 22a to 22h Ground pad 23 Power supply pad 24 Resist layers 25a to 25d Land 30 Chip elements 31a and 31b Chip element terminals

Claims (4)

A dielectric substrate;
A patch electrode formed on the upper surface of the substrate;
A ground electrode formed on the bottom surface of the substrate;
A feeding electrode formed on a part of the bottom surface of the substrate and insulated and separated from the ground electrode;
All side surfaces of the substrate are insulating surfaces without electrode patterns,
The patch antenna, wherein the feeding electrode is capacitively coupled to the patch electrode. The feeding electrode is a rectangular pattern;
One side of the power supply electrode is in contact with the edge of the substrate and is provided at the center in the width direction of the edge,
2. The patch antenna according to claim 1, wherein the other three sides of the feeding electrode are opposed to the ground electrode through an insulating gap region having a predetermined width. Further comprising corner electrodes formed at the four corners of the bottom surface of the substrate and insulated from the ground electrode;
The patch antenna according to claim 1, wherein a chip element is connected to the corner electrode.   The patch antenna according to claim 3, wherein the chip element includes two terminals, one terminal is connected to the corner electrode, and the other terminal is connected to the ground.

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