JP2014150334A - Folded dipole antenna and communication device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a folded dipole antenna having a high radiation resistance and a communication device using the same.
SOLUTION: A dielectric substrate 20, a first line-shaped conductor 11 provided on or inside a first main surface of the dielectric substrate 20, and the first line-shaped conductor 11 are opposed to each other through a dielectric. The first line-shaped conductor 12 to which the feeder line is connected, the first line-shaped conductor 11 and the first line-shaped conductor 12 and both ends of the second line-shaped conductor 12 and Characteristic impedance of a transmission line that includes the first line-shaped conductor 11, the second line-shaped conductor 12, and the dielectric substrate 20, and has the second connection conductor 52. A folded dipole antenna characterized by being smaller than four times the radiation impedance of a dipole antenna composed only of a line-shaped conductor 12 and a communication device using the same.
[Selection] Figure 2

Description

  The present invention relates to a folded dipole antenna and a communication apparatus using the same.

  A technique for reducing the size by inserting an inductor into a dipole antenna is known. Further, a folded dipole antenna is known as a dipole antenna whose radiation resistance is increased in order to increase radiation efficiency (see, for example, Patent Document 1).

JP 2012-105189 A

  However, the radiation resistance of the conventional folded dipole antenna is not sufficient. In particular, when an inductor is inserted in order to reduce the size, there is a problem that the radiation resistance is reduced, thereby reducing the radiation efficiency.

  The present invention has been devised in view of such problems in the prior art, and an object thereof is to provide a folded dipole antenna having a high radiation resistance and a communication device using the same.

  The folded dipole antenna of the present invention includes a dielectric substrate, a first line-shaped conductor provided on or inside the first main surface of the dielectric substrate, and the dielectric that forms the dielectric substrate. A second line-like shape provided on the second main surface or inside of the dielectric substrate so as to face the first line-like conductor and having a pair of feed lines connected to the center in the length direction. A conductor, a first connecting conductor connecting one ends of the first line-shaped conductor and the second line-shaped conductor, and the other end of the first line-shaped conductor and the second line-shaped conductor. A folded dipole antenna having at least a second connection conductor for connecting each other, and a characteristic impedance of a transmission line composed of the first line-shaped conductor, the second line-shaped conductor, and the dielectric substrate However, the dielectric substrate It is characterized in that fine second line conductor only less than 4 times the radiation impedance of the structure the dipole antenna.

  The communication apparatus according to the present invention includes at least the dipole antenna and at least one of a receiving circuit and a transmitting circuit connected to the folded dipole antenna.

  According to the folded dipole antenna of the present invention, an antenna having high radiation resistance can be obtained. According to the communication device of the present invention, a high-performance communication device can be obtained.

It is a perspective view which shows typically the structure of the folding | turning dipole antenna of the 1st example of embodiment of this invention. It is a perspective view which shows typically the structure of the folding | turning dipole antenna of the 1st example of embodiment of this invention. FIG. 2 is a cross-sectional view taken along line A-A ′ of FIG. 1. FIG. 2 is a sectional view taken along line B-B ′ of FIG. 1. It is a perspective view which shows typically the structure of the folding | turning dipole antenna of the 2nd example of embodiment of this invention. It is a perspective view which shows typically the structure of the folding | turning dipole antenna of the 2nd example of embodiment of this invention. FIG. 6 is a sectional view taken along line C-C ′ of FIG. 5. It is a block diagram which shows typically the communication apparatus of the 3rd example of embodiment of this invention. It is a graph which shows the radiation characteristic of a return | turnback dipole antenna.

  Hereinafter, a folded dipole antenna of the present invention and a communication device using the same will be described in detail with reference to the accompanying drawings.

(First example of embodiment)
1 and 2 are perspective views schematically showing a configuration of a folded dipole antenna according to a first example of an embodiment of the present invention. 3 is a cross-sectional view taken along line AA ′ of FIG. 4 is a cross-sectional view taken along the line BB ′ of FIG. Note that FIG. 2 shows a state where the dielectric substrate 20 in FIG. 1 is seen through.

  As shown in FIGS. 1 to 4, the folded dipole antenna of this example includes a dielectric substrate 20, a first line-shaped conductor 11, a second line-shaped conductor 12, a first connection conductor 51, The second connection conductor 52, the feed line 31, and the feed line 32 are provided.

  The relative dielectric constant of the dielectric substrate 20 is, for example, about 2 to 20. The material of the dielectric substrate 20 is not particularly limited, and a resin such as glass epoxy can be used. However, from the viewpoint of accuracy and ease of manufacture when the dielectric substrate 20 is formed. It is desirable to use dielectric ceramics. The thickness of the dielectric substrate 20 is, for example, about 10 μm to 10 mm.

  The first line-shaped conductor 11 is provided on the first main surface 20 a of the dielectric substrate 20. The second line-shaped conductor 12 is provided on the second main surface 20b of the dielectric substrate 20 so as to face the first line-shaped conductor 11 with the dielectric forming the dielectric substrate 20 interposed therebetween. . A pair of feed lines 31 and 32 are connected to the center of the second line-shaped conductor 12 in the length direction. Specifically, the center in the length direction of the second line-shaped conductor 12 is divided, and the feed line 31 is connected to one end of the divided portion, and the other end of the divided portion is fed. A line 32 is connected. That is, the second line-shaped conductor 12 is divided into a line-shaped conductor 12a and a line-shaped conductor 12b having the same length, and the feed line 31 is connected to the end of the line-shaped conductor 12a in the divided portion. The feeder line 32 is connected to the end of the line-shaped conductor 12b in the divided portion. Further, the lengths of the first line-shaped conductor 11 and the second line-shaped conductor 12 are basically set to ½ of the wavelength of the operating frequency.

  The first connection conductor 51 is provided so as to penetrate the dielectric substrate 20, and connects one ends of the first line-shaped conductor 11 and the second line-shaped conductor 12. The second connection conductor 52 is provided so as to penetrate the dielectric substrate 20, and connects the other ends of the first line-shaped conductor 11 and the second line-shaped conductor 12.

The first line-shaped conductor 11, the second line-shaped conductor 12, the feed line 31, the feed line 32, the first connection conductor 51, and the second connection conductor 52 are formed using various conductive materials. can do. For example, it can be formed using a highly conductive metal such as gold, silver, copper, and alloys thereof. Moreover, the thickness of the 1st line-shaped conductor 11, the 2nd line-shaped conductor 12, the feed line 31, and the feed line 32 shall be about 3 micrometers-50 micrometers, for example. As the first connection conductor 51 and the second connection conductor 52, for example, a through hole or a via hole can be preferably used.

  The folded dipole antenna of this example having such a configuration is folded back by the first line-shaped conductor 11, the second line-shaped conductor 12, the first connection conductor 51, the second connection conductor 52, and the dielectric substrate 20. A dipole antenna is configured and functions as a folded dipole antenna by being fed through the feed lines 31 and 32.

  In the folded dipole antenna of this example, the characteristic impedance of the transmission line composed of the first line-shaped conductor 11, the second line-shaped conductor 12, and the dielectric substrate 20 is such that the dielectric substrate 20 and the second line-shaped conductor It is set to be smaller than four times the radiation impedance of a dipole antenna composed of only 12.

For example, as shown in FIG. 4, the transmission line composed of the first line-shaped conductor 11, the second line-shaped conductor 12, and the dielectric substrate 20 is disposed so as to face the transmission line. This is a transmission line in which an electrical signal is transmitted in a direction perpendicular to the paper surface by the two line conductors of the first line-shaped conductor 11 and the second line-shaped conductor 12. The characteristic impedance of the transmission line can be obtained by measurement or simulation. For example, in the case of the structure shown in FIG. 4, the width of the first line-shaped conductor 11 and the second line-shaped conductor 12 is w. The distance between the first line-shaped conductor 11 and the second line-shaped conductor 12 is d, the relative permittivity of the dielectric substrate 20 is ε _r , the relative permeability μ _r of the dielectric substrate 20 is fringing When the coefficient is K, the characteristic impedance Z _t of the transfer line is
Z _t = 377 / K × (μ _r / ε _r ) ^0.5 × d / w
Can also be calculated. That is, in order to reduce the the characteristic impedance Z _t of the transfer line is to increase the specific dielectric constant epsilon _r of the dielectric substrate 20, increasing the width w of the first line conductor 11 and the second line-shaped conductors 12 Then, the distance d between the first line-shaped conductor 11 and the second line-shaped conductor 12 may be reduced.

  Radiation impedance of a dipole antenna composed only of the second line-shaped conductor 12 (a dipole antenna without the first line-shaped conductor 11, the first connecting conductor 51, and the second connecting conductor 52 removed) is It can be obtained by measurement or simulation. Further, four times the radiation impedance of the non-folded dipole antenna matches the radiation impedance of the folded dipole antenna.

  That is, the characteristic impedance of the transmission line composed of the first line-shaped conductor 11, the second line-shaped conductor 12 and the dielectric substrate 20 is a dipole composed only of the dielectric substrate 20 and the second line-shaped conductor 12. By setting it to be smaller than four times the radiation impedance of the antenna, the current can easily flow through the folded dipole antenna in the transmission line mode (non-radiation mode). Thereby, the anti-resonance of the non-radiation mode can be generated in the vicinity of the resonance frequency of the radiation mode in which the antenna radiates electromagnetic waves, so that the radiation resistance can be increased. Thereby, a folded dipole antenna with high radiation efficiency can be obtained.

(Second example of embodiment)
5 and 6 are perspective views schematically showing the configuration of the folded dipole antenna of the first example of the embodiment of the present invention. 7 is a cross-sectional view taken along the line CC ′ of FIG. FIG. 6 shows a state where the dielectric substrate 20 in FIG. 5 is seen through. Moreover, in this example, a different part from the 1st example of embodiment mentioned above is demonstrated, the same referential mark is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

  As shown in FIGS. 5 to 7, the folded dipole antenna of this example includes a first line-shaped conductor 11 in addition to the folded dipole antenna of the first example of the embodiment shown in FIGS. 1 to 4. It further has inductors 41 and 42 inserted, and inductors 43 and 44 inserted into the second line-shaped conductor 12. That is, in the folded dipole antenna of this example, an inductor is inserted in each of the first line-shaped conductor 11 and the second line-shaped conductor 12. As the inductors 41, 42, 43, and 44, various known inductors can be used. For example, a chip inductor may be used, and the inductor may be formed by a conductor pattern.

  Specifically, the second line-shaped conductor 12 is divided by the first divided portion located in the center in the length direction, and the second and third divided portions located in the vicinity of both sides of the divided portion. Further divided in part. Therefore, the second line-shaped conductor 12 is divided into four in order from one end thereof: a line-shaped conductor 12c, a line-shaped conductor 12d, a line-shaped conductor 12e, and a line-shaped conductor 12f. Feed lines 31 and 32 are connected to the first divided portion (the central divided portion in the length direction of the second line-shaped conductor 12 and the divided portion of the line-shaped conductor 12d and the line-shaped conductor 12e). ing. An inductor 43 is disposed in the second divided portion (the divided portion of the line-shaped conductor 12c and the line-shaped conductor 12d), and the line-shaped conductor 12c and the line-shaped conductor 12d are connected via the inductor 43. . An inductor 44 is disposed in the third divided portion (the divided portion of the line-shaped conductor 12e and the line-shaped conductor 12f), and the line-shaped conductor 12e and the line-shaped conductor 12f are connected via the inductor 44. Yes.

  Further, the first line-shaped conductor 11 is opposed to the fourth divided portion at a position facing the second divided portion with the dielectric substrate 20 in between, and the third divided portion with the dielectric substrate 20 in between. It is divided by two division parts, the fifth division part at the position to be. Therefore, the first line-shaped conductor 11 is divided into three, the line-shaped conductor 11a, the line-shaped conductor 11b, and the line-shaped conductor 11c in order from one end thereof. An inductor 41 is disposed in the fourth divided portion (the divided portion between the line-shaped conductor 11a and the line-shaped conductor 11b), and the line-shaped conductor 11a and the line-shaped conductor 11b are connected via the inductor 41. . An inductor 42 is disposed in the fifth divided portion (the divided portion of the line-shaped conductor 11b and the line-shaped conductor 11c), and the line-shaped conductor 11b and the line-shaped conductor 11c are connected via the inductor 24. Yes.

  In the folded dipole antenna of this example having such a configuration, an inductor is inserted in each of the first line-shaped conductor 11 and the second line-shaped conductor 12, and therefore the first line-shaped conductor 11 and the second line-shaped conductor 11 The length of the two line-shaped conductors 12 can be shortened. Thereby, a further smaller folded dipole antenna can be obtained.

(Third example of embodiment)
FIG. 8 is a block diagram schematically showing a communication apparatus according to a third example of the embodiment of the present invention. The communication apparatus of this example includes a folded dipole antenna 81 of the first example of the embodiment, and a reception circuit 83 and a transmission circuit 84 connected to the folded dipole antenna 81. An antenna duplexer is inserted between the folded dipole antenna 81 of the first example and the reception circuit 83 and the transmission circuit 84. The reception circuit 83 and the transmission circuit 84 are connected via the antenna duplexer 82. Are connected to the folded dipole antenna 81.

Thus, the communication device of this example includes the folded dipole antenna 81 of the first example of the embodiment, and the reception circuit 83 and the transmission circuit 84 connected to the folded dipole antenna 81.
At least one of the above. As a result, at least one of transmission and reception of communication signals can be performed using the folded dipole antenna 81 having a high radiation resistance, so that a high-performance communication device can be obtained.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the spirit of the present invention.

  For example, in FIGS. 1 to 7, in order to simplify the illustration, the case where the first line-shaped conductor 11 and the second line-shaped conductor 12 are linear is illustrated, but the present invention is not limited thereto. is not. The first line-shaped conductor 11 and the second line-shaped conductor 12 may have any shape and arrangement that overlap each other when the dielectric substrate 20 is viewed from above, and may have various shapes.

  In the third example of the above-described embodiment, the example in which the folded dipole antenna of the first example of the embodiment is used as the folded dipole antenna is shown, but the present invention is not limited to this. The folded dipole antenna of the second example of the embodiment may be used, or a folded dipole antenna having another structure may be used.

  First, the radiation characteristics of the first folded dipole antenna that is the folded dipole antenna of the second example of the embodiment of the present invention shown in FIGS. 5 to 7 were calculated by simulation. In this simulation, the dielectric constant of the dielectric substrate 20 was set to 3.1. The first line-shaped conductor 11 and the second line-shaped conductor 12 each had a width of 50 μm and a total length of 300 mm. The distance between the first line-shaped conductor 11 and the second line-shaped conductor 12 (d in FIG. 4) was 50 μm. The inductances of the inductors 41, 42, 43, and 44 are 500 nH, respectively. At this time, the radiation impedance of the dipole antenna (non-folded dipole antenna) constituted only by the dielectric substrate 20 and the second line-shaped conductor 12 was 61Ω, and four times that was 244Ω. The characteristic impedance of the transmission line composed of the first line-shaped conductor 11, the second line-shaped conductor 12, and the dielectric substrate 20 was 72Ω, which was smaller than 244Ω.

  In addition, the radiation characteristics of the second folded dipole antenna as a comparative example were simulated. In the second folded dipole antenna, the first line-shaped conductor 11 is arranged on the second main surface 20b of the dielectric substrate 20 side by side with the second line-shaped conductor 12 to thereby form the first line-shaped conductor. Both ends of the conductor 11 and the second line-shaped conductor 12 were connected by connecting conductors. The distance between the first line-shaped conductor 11 and the second line-shaped conductor 12 was 10 mm. The inductances of the inductors 41, 42, 43, and 44 are 400 nH, respectively. Other conditions were the same as those of the first folded dipole antenna. At this time, the radiation impedance of the dipole antenna (non-folded dipole antenna) constituted only by the dielectric substrate 20 and the second line-shaped conductor 12 was 61Ω, and four times that was 244Ω. The characteristic impedance of the transmission line constituted by the first line-shaped conductor 11, the second line-shaped conductor 12, and the dielectric substrate 20 was 720Ω, which was larger than 244Ω.

  The simulation result of the radiation characteristic is shown in FIG. In the graph shown in FIG. 9, the horizontal axis indicates the frequency, and the vertical axis indicates the real part of the impedance. Further, the radiation characteristic of the first folded dipole antenna is indicated by a solid line, and the radiation characteristic of the second folded dipole antenna is indicated by a broken line. According to the graph, in the radiation characteristic of the first folded dipole antenna, the anti-resonance of the transmission line mode (non-radiation mode) occurs in the vicinity of 250 MHz, and thereby the value of the real part of the impedance at the frequency in the vicinity thereof. It can be seen that is increasing.

  The resonance frequency of the radiation mode of the second folded dipole antenna was 206 MHz, and the radiation resistance at that time was 55.9Ω. The resonance frequency of the radiation mode of the first folded dipole antenna was 220 MHz, and the radiation resistance at that time was 64.4Ω, which was higher than the radiation resistance of the second folded dipole antenna. Thereby, the effectiveness of the present invention was confirmed.

11: 1st line conductor 12: 2nd line conductor 20: Dielectric substrate 31, 32: Feed line 51: 1st connection conductor 52: 2nd connection conductor 41, 42, 43, 44: Inductor 81: Folded dipole antenna 83: Reception circuit 84: Transmission circuit

Claims (3)

A dielectric substrate;
A first line-shaped conductor provided on or inside the first main surface of the dielectric substrate;
The dielectric substrate is provided on the second main surface or inside of the dielectric substrate so as to face the first line-shaped conductor via a dielectric forming the dielectric substrate, and at the center in the length direction. A second line-shaped conductor to which a pair of feed lines are connected;
A first connection conductor connecting one ends of the first line-shaped conductor and the second line-shaped conductor; and
A second connection conductor connecting the other ends of the first line-shaped conductor and the second line-shaped conductor;
A folded dipole antenna having at least
The characteristic impedance of the transmission line composed of the first line-shaped conductor, the second line-shaped conductor, and the dielectric substrate is a dipole antenna composed of only the dielectric substrate and the second line-shaped conductor. A folded dipole antenna characterized by being smaller than four times the radiation impedance.   The folded dipole antenna according to claim 1, wherein an inductor is inserted into each of the first line-shaped conductor and the second line-shaped conductor.   A communication apparatus comprising: the folded dipole antenna according to claim 1 or 2; and at least one of a reception circuit and a transmission circuit connected to the folded dipole antenna.

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