JP2005124048A - Antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device in which a bandwidth does not become narrow undesirably even if a patch antenna element is made smaller by using a dielectric substrate with high permittivity, thereby improving a manufacturing yield. <P>SOLUTION: In a patch antenna element 10, a patch electrode 13 and a ground electrode 14 are provided at the ceiling face and the bottom face of a dielectric substrate 12, and a power feeding pin 15 is connected to the power feeding point of the patch electrode 13. In this case, the dielectric substrate 12 is made of a material with high permittivity (specific inductive capacity of about 90) to promote the miniaturization of a body. By mounting the patch antenna element 10 on the edge of a region where a ground conducting portion 16 is formed on one face of a circuit board 11, an increase in Q value accompanying the miniaturization can be suppressed and a bandwidth can be extended. As an example, a projected edge 16a extended from the ground conductor 16 is formed, and the patch antenna element 10 may be mounted on the projected edge 16a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antenna device in which a patch antenna element having a patch electrode provided on the top surface of a dielectric substrate is mounted on a circuit board, and more particularly to a patch antenna element using a dielectric substrate having a high dielectric constant. The present invention relates to an antenna device that promotes downsizing.

  Patch antenna elements that are suitable for miniaturization and can be manufactured at a relatively low cost are widely used in antenna devices for vehicles and the like. Such a patch antenna element is provided with a patch electrode (radiation conductor) and a ground electrode on both surfaces of a dielectric substrate made of a dielectric material such as ceramic, and one end of a feed pin or a feed line is connected to a feed point of the patch electrode on the top surface side. It is roughly configured by connecting. An antenna that secures a desired gain by mounting such a patch antenna element on a circuit board provided with a wide ground conductor and connecting the other end of the feed pin or feed line to the antenna circuit on the circuit board side. An apparatus is obtained (for example, refer to Patent Document 1).

  FIG. 7 is a plan view showing a conventional example of this type of antenna device, in which a patch antenna element 1 for GPS (Global Positioning System) is mounted on a circuit board 2. The patch antenna element 1 includes a rectangular dielectric substrate 3 made of ceramic or the like, a patch electrode 4 having a predetermined shape provided on the top surface of the dielectric substrate 3, and a diagram provided on the bottom surface of the dielectric substrate 3. A ground electrode (not shown) and a power feed pin 5 that passes through the dielectric substrate 3 and is connected to a power feed point of the patch electrode 4 are configured so that the power feed pin 5 is kept in contact with the ground electrode. . In addition, a ground conductor portion 6 is provided almost entirely on the upper surface side of the circuit board 2 on which the patch antenna element 1 is mounted. Although not shown, a filter portion or An antenna circuit including an amplifying unit and the like is provided. The antenna circuit is connected to the feed pin 5, and the patch electrode 4 is excited by supplying a predetermined high-frequency power to the patch electrode 4 through the feed pin 5. Since the patch antenna element 1 is mounted near the center on the wide ground conductor portion 6 as shown in FIG. 7, the efficiency is increased by the electric field generated between the patch electrode 4 and the wide ground conductor portion 6 during excitation. It is possible to radiate radio waves well.

In such an antenna device, in recent years, the patch antenna element 1 has been remarkably miniaturized in order to meet demands for facilitating high-density mounting and multi-functionalization of the circuit board 2. Specifically, instead of a ceramic having a relative dielectric constant of about 35, which is generally used as a material for the dielectric substrate 3 of the patch antenna element 1, a ceramic having a significantly high relative dielectric constant (for example, about 90) is used. For example, the wavelength shortening effect is remarkably increased, and the size of the patch electrode 4 can be considerably reduced. That is, when the patch electrode is a square having a side length L, the value of L can be set to about λ / (2√ε), where λ is the resonance length and ε is the dielectric constant of the dielectric substrate. Therefore, by increasing the value of the relative dielectric constant ε, the area of the patch electrode can be reduced and the size reduction of the patch antenna element can be promoted.
JP 2001-94336 A (page 2, FIG. 9)

  As described above, it is possible to promote downsizing of the patch antenna element by using a ceramic having a relative dielectric constant of, for example, about 90. However, when the dielectric substrate having such a high dielectric constant is used, the sharpness of antenna resonance is achieved. Since the Q value indicating the value increases and the bandwidth is narrowed, a decrease in manufacturing yield due to the narrowing of bandwidth becomes a problem. In other words, if the bandwidth is too narrow, a product whose resonance frequency is slightly deviated from the optimum value at a manufacturing site where mass production of antenna devices will result in a defective product with insufficient sensitivity, resulting in a reduction in yield. Incurs an increase in cost.

  The present invention has been made in view of such a state of the art, and the purpose thereof is to reduce the bandwidth undesirably even if the patch antenna element is miniaturized using a dielectric substrate having a high dielectric constant. Accordingly, an object of the present invention is to provide an antenna device capable of improving the manufacturing yield.

  In order to achieve the above-described object, in the antenna device of the present invention, a dielectric substrate made of a dielectric material having a relative dielectric constant of 70 or more, a patch electrode provided on the top surface of the dielectric substrate, and the patch electrode A patch antenna element having a feeding means connected to the feeding point is mounted on the edge of a region where the ground conductor is formed on one side of the circuit board.

  When the patch antenna element is mounted on the edge portion on the ground conductor portion of the circuit board in this way, the radiation efficiency is slightly reduced because there is no wide ground conductor portion on the edge portion side. On the other side, the radiation efficiency can be increased by providing a wide ground conductor on the circuit board, so that an antenna device with a reduced Q value indicating the sharpness of resonance can be obtained. Therefore, even when the dielectric constant of the material of the dielectric substrate is set to 70 or more, preferably 90 or more, and the downsizing of the patch antenna element is promoted, the increase in the Q value can be suppressed, so that the bandwidth is widened. The manufacturing yield of the device is improved and the cost can be greatly reduced.

  In the antenna device having such a configuration, the shape of the patch antenna element is not particularly limited. For example, when the dielectric substrate of the patch antenna element is rectangular in plan view, at least one side surface of the dielectric substrate is a circuit board. What is necessary is just to arrange | position in the vicinity of the outer edge of this ground conductor part substantially parallel. Furthermore, when the necessity to suppress the Q value and widen the bandwidth is particularly high, a rectangular protruding edge portion on which the patch antenna element is mounted is extended to the ground conductor portion, which is the outer edge of the protruding edge portion. Three different side surfaces of the dielectric substrate of the patch antenna element may be arranged substantially in parallel in the vicinity of the three sides.

  In the antenna device of the present invention, a patch antenna element using a dielectric base having a high dielectric constant (relative permittivity is 70 or more) to promote downsizing, and a ground conductor portion is formed on one side of a circuit board. Since it is mounted on the edge of the region, the bandwidth can be expanded while suppressing the Q value. Therefore, in a manufacturing site where such an antenna device is mass-produced, even if the resonance frequency is slightly deviated from the optimum value, the antenna performance becomes a non-defective product, so that the manufacturing yield can be improved and a significant cost reduction can be expected.

  An embodiment of the invention will be described with reference to the drawings. FIG. 1 is a plan view of an antenna device according to an embodiment of the present invention, and FIG. 2 is a side view of a main part of the antenna device.

  The antenna device shown in these drawings is a GPS antenna in which a patch antenna element 10 is mounted at a predetermined position on a circuit board 11. The patch antenna element 10 includes a dielectric substrate 12 having a rectangular shape in plan view, a patch electrode 13 having a predetermined shape provided on the top surface of the dielectric substrate 12, and a ground electrode 14 provided on the bottom surface of the dielectric substrate 12. The power supply pin 15 passes through the dielectric substrate 12 and is connected to the power supply point of the patch electrode 13. The power supply pin 15 is kept in contact with the ground electrode 14. Here, the dielectric substrate 12 is made of a high dielectric constant material having a relative dielectric constant of 70 or more. In the case of this embodiment, the dielectric substrate 12 is made of a ceramic having a relative dielectric constant of about 90. By using 12, the patch antenna element 10 is remarkably miniaturized.

  On the other hand, a ground conductor portion 16 is provided on almost the entire surface on the upper surface side of the circuit board 11, and an antenna circuit 17 including a filter portion and an amplification portion is disposed on the lower surface side of the circuit board 11. . On the lower surface side of the circuit board 11 is also provided a ground conductor portion 18 that is electrically connected to the ground conductor portion 16 on the upper surface side through a through hole (not shown). As shown in FIG. 1, a part of the circuit board 11 protrudes as a rectangular protrusion 11a, and a rectangular protruding edge 16a of the ground conductor 16 extends from the upper surface of the rectangular protrusion 11a. The patch antenna element 10 is mounted on 16a. Specifically, the patch antenna element 10 is arranged in a state where three different side surfaces of the dielectric base 12 are arranged substantially in parallel in the vicinity of the three sides constituting the U-shaped outer edge of the protruding edge portion 16a. Is mounted on the protruding edge 16a. However, the feed pin 15 of the patch antenna element 10 is not in contact with the ground conductor portion 16 and is connected to the antenna circuit 17 through the circuit board 11. The patch electrode 13 is excited by supplying predetermined high-frequency power to the patch electrode 13 via the power supply pin 15.

  An electric field is generated between the patch electrode 13 and the ground conductors 16 and 18 at the time of excitation, and radio waves are radiated, but the patch antenna element 10 is mounted on the protruding edge 16a of the ground conductor 16. Although the ground conductor portion 16 extends on one side of the patch antenna element 10 when viewed from above, the wide ground conductor portion 16 does not exist on the remaining three sides of the patch antenna element 10 (see FIG. 1). ). Therefore, as shown by the arrows in FIG. 2, a strong electric field is generated between the patch electrode 13 and the ground conductor portion 16 on the side where the wide ground conductor portion 16 exists, and the radiation efficiency is increased. On the other side, Since the electric field between the patch electrode 13 that goes around the circuit board 11 and the ground conductor portion 18 becomes dominant, the radiation efficiency slightly decreases. As a result, the antenna device according to the present embodiment has a wide bandwidth by suppressing an increase in the Q value accompanying the downsizing of the patch antenna element 10.

FIG. 3 is a characteristic diagram showing the return loss (reflection loss) according to the frequency of the antenna device according to the present embodiment. As a comparative example, the patch antenna element 10 is mounted near the center on the ground conductor portion 16. The return loss is also shown. For this example embodiment is equipped with a patch antenna element 10 on the protruding edge 16a of the ground conductor 16, the return loss becomes like the characteristic curve indicated by the solid line in FIG. 3, slightly from the resonance frequency f ₀ It can be seen that even at the shifted frequency, the bandwidth is increased to −10 dB or less. Return contrast, the comparative example provided with the patch antenna element 10 near the center of the ground conductor portion 16 becomes the characteristic curve so indicated by the broken line in FIG. 3, at the resonant frequency f ₀ for Q value is very large It can be seen that the loss suddenly decreases and the return loss exceeds -10 dB just by shifting the frequency slightly from f ₀ . In a manufacturing site where mass production of an antenna device having a very narrow bandwidth as in this comparative example, a product whose resonance frequency is slightly deviated from the optimum value becomes a defective product with insufficient sensitivity, so the yield is extremely poor. Become.

  As described above, in the antenna device according to this embodiment, the patch antenna element 10 is projected from the ground conductor portion 16 while promoting the miniaturization of the patch antenna element 10 using the dielectric substrate 12 having a high dielectric constant. Since the Q value indicating the sharpness of resonance is intentionally reduced by being mounted on the edge portion 16a, a desired bandwidth is ensured while the patch antenna element 10 is ultra-compact. Therefore, at the manufacturing site where the antenna device is mass-produced, even if the resonance frequency is slightly deviated from the optimum value, the antenna performance becomes a non-defective product, so that the manufacturing yield can be improved and a significant cost reduction can be expected.

  In the embodiment described above, since the patch antenna element 10 is mounted on the protruding edge portion 16a extended to the ground conductor portion 16, the effect of suppressing the Q value and widening the bandwidth is increased. When the manufacturing yield is remarkably improved by slightly widening the bandwidth, or when it is necessary to avoid a decrease in gain as much as possible, the protruding edge portion 16a may be omitted. For example, as shown in the plan view of FIG. 4, when the patch antenna element 10 is mounted in the vicinity of the center of one side of the ground conductor portion 16, only one side surface of the dielectric base 12 is in the vicinity of the outer edge of the ground conductor portion 16. Since the remaining three side surfaces of the dielectric substrate 12 are exposed to the wide ground conductor portion 16, the Q value is slightly lowered, but there is still an effect of slightly increasing the bandwidth. . Further, as shown in the plan view of FIG. 5, when the patch antenna element 10 is mounted at the corner of the ground conductor portion 16, the two side surfaces of the dielectric base 12 are arranged near the outer edge of the ground conductor portion 16. Since the remaining two side surfaces of the dielectric base 12 are exposed to the wide ground conductor portion 16, the bandwidth is wider than that of the antenna device shown in FIG. 4, which is larger than that of the embodiment shown in FIG. Becomes narrower.

  The present invention is also applicable when the dielectric substrate of the patch antenna element is not rectangular in plan view. For example, in the patch antenna element 20 shown in the plan view of FIG. 6, the dielectric substrate 12 is circular in plan view and the patch electrode 13 is also substantially circular, but a tongue-like protruding edge portion 16 b is extended from the ground conductor portion 16. By mounting the patch antenna element 20 on the protruding edge portion 16b, it is possible to expect substantially the same effect as that of the embodiment shown in FIG.

It is a top view of the antenna device concerning the example of an embodiment of the present invention. It is a principal part side view of this antenna apparatus. It is a characteristic view which shows the return loss according to the frequency of this antenna apparatus and a comparative example. It is a top view of the antenna apparatus which concerns on the other embodiment of this invention. FIG. 10 is a plan view of an antenna device according to still another embodiment of the present invention. FIG. 10 is a plan view of an antenna device according to still another embodiment of the present invention. It is a top view of the antenna device which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Patch antenna element 11 Circuit board 12 Dielectric substrate 13 Patch electrode 14 Ground electrode 15 Feed pin 16 Ground conductor part 16a, 16b Protruding edge part 17 Antenna circuit

Claims (4)

  A patch antenna comprising a dielectric substrate made of a dielectric material having a relative dielectric constant of 70 or more, a patch electrode provided on the top surface of the dielectric substrate, and a feeding means connected to a feeding point of the patch electrode An antenna device, wherein an element is mounted on an edge portion of a region where a ground conductor portion is formed on one side of a circuit board.   2. The antenna device according to claim 1, wherein the dielectric material has a relative dielectric constant of 90 or more.   3. The dielectric substrate according to claim 1, wherein the dielectric substrate has a rectangular shape in a plan view, and at least one side surface of the dielectric substrate is disposed substantially parallel to the vicinity of the outer edge of the ground conductor portion. Antenna device. 4. A rectangular protruding edge portion on which the patch antenna element is mounted is extended to the ground conductor portion according to claim 3, and the phase of the dielectric substrate is respectively near three sides that are outer edges of the protruding edge portion. An antenna device characterized in that three different side surfaces are arranged substantially in parallel.

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