JP3206825B2 - Printed antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed antenna suitable for being incorporated in a mobile communication device such as a portable telephone.

[0002]

2. Description of the Related Art A printed antenna can be manufactured with a small variation in electrical characteristics by forming an antenna pattern by applying a precision etching technique to a copper foil using a high-frequency copper-clad laminate or the like. Particularly, it is widely used in a frequency band of 800 MHz or more, in which assembly accuracy is required. Among such printed antennas, a plate-shaped inverted-F antenna is suitable for being incorporated in a mobile communication device such as a portable wireless device such as a mobile phone.

FIG. 11 (a) shows a plate-shaped inverted-F type antenna formed by a printed antenna, and an antenna element formed by a copper foil as a patch on one surface of a dielectric layer 10 formed by a laminated board or the like. 11, a ground conductor 12 made of copper foil is laminated on the other side. A pair of through holes are provided close to the end of the dielectric layer 10 and a conductor is provided by plating or the like on the inner periphery of each through hole, and the antenna element 11 is grounded to the ground conductor 12 by one of the through holes. And a feeder 3 for connecting the antenna element 11 to a coaxial cable connection land 13 provided on a part of the ground conductor 12 is formed by the other through hole.
FIG. 11B shows the principle of the plate-shaped inverted-F antenna of FIG. 11A, and the same parts are denoted by the same reference numerals. In FIG. 11B, 14 is a coaxial cable, and 15 is a coaxial connector.

In the plate-shaped inverted-F antenna shown in FIG. 11A, a rectangular antenna element (patch) 11 is formed.
Are approximately 1/8 of the electrical length
Although it is a wavelength, the actual size is further reduced by 1 / √ε due to the dielectric constant ε of the dielectric layer 10. The distance C between the grounding section 2 and the power supply section 3 is selected so as to match the characteristic impedance of the coaxial cable 14. If C is large, the impedance is high, and if C is small, the impedance is low.

A practical example of each dimension is as follows: 820 MHz plate-shaped inverted F using a dielectric layer 10 of ε = 3.5 and a thickness of 5 mm.
The size of the antenna element 11 of the type antenna is A = B = 28
mm (the size of the dielectric layer 10 serving as the substrate is 30 mm
Corner), and the distance C between the ground part 2 and the power supply part 3 is 2 mm. In this case, a conductor plate 1 having a size of 140 mm × 40 mm as an external ground plate as shown in FIG.
The antenna characteristics when 6 is attached to the ground conductor 12 and added are as shown in FIGS. 13 (a), 13 (b) and 13 (c). FIG. 13A shows the XY plane directivity characteristics, and FIG.
13 shows the YZ plane directional characteristics, and FIG. 13C shows the ZX plane directional characteristics, respectively. The peak gains for vertical polarization are -0.2 dBD and-, respectively, as shown.
0.2 dBD and -0.7 dBD (both are dipole antenna ratios). The frequency bandwidth defined by VSWR = 2 is 4.9%. As you can see in this example,
A plate-shaped inverted-F antenna made of a printed antenna has a wide range of directivity suitable for a portable wireless device such as a mobile phone.

[0006]

As is apparent from the purpose of use, portable wireless devices such as portable telephones are required to be as small and light as possible. Therefore, it is required to further reduce the size of the above-mentioned plate-shaped inverted-F antenna made of a printed antenna. To reduce the size, it is necessary to form the dielectric layer 10 serving as a substrate with a high dielectric constant material. I just need. For example, in the above example, an antenna element of ε = 3.5 is used. However, when an antenna element of ε = 14 is used, the antenna element 1 required to resonate at the same frequency due to the wavelength shortening effect is used.
1 is √ (3.5 / 14) = １ ／, that is, the antenna element 11 having a size of 28 mm square as described above.
Is reduced to a size of 14 mm square, and the mounting area is 1/4
It becomes.

[0007] However, high-permittivity materials having good high-frequency characteristics are generally expensive and have the drawback of poor workability. Further, there is a problem that the specific gravity is generally large and the weight cannot be reduced even if the size can be reduced. The present invention has been made in view of the above points, and has as its object to provide a printed antenna that can be reduced in size and weight without using a high dielectric constant material.

[0008]

A printed antenna according to the present invention has a loop-shaped conductor foil 1 whose one end is grounded by a grounding portion 2 and a feeder which is connected to the loop-shaped conductor foil 1 in close proximity to the grounding portion 2. And a reactant loading means formed by deforming a part of the loop-shaped conductor foil 2.

In the present invention, the reactance loading means can be formed by the loading inductance formed by bending a part of the loop-shaped conductor foil 1 in a zigzag manner. Further, in the present invention, the reactance loading means can be formed by a loading capacitance formed by widening a part of the loop-shaped conductor foil 1 at a position distant from the grounding portion 2.

Further, in the present invention, a comb-shaped member formed between a part of the loop-shaped conductor foil 1 located at a position distant from the grounding portion 2 and a ground conductor 4 separate from the loop-shaped conductor foil 1. The reactance loading means can also be formed by the loading capacitance due to the structure.

[0011]

A linear antenna structure is formed with the loop-shaped conductor foil 1 without changing the operation mode of the plate-shaped inverted-F antenna, and a part of the loop-shaped conductor foil 1 is deformed to form reactance loading means. Therefore, the antenna length can be shortened and the size can be reduced by the reactance loading means.

[0012]

The present invention will be described below in detail with reference to examples. FIG.
(A) shows the principle of a plate-shaped inverted-F antenna formed with the loop-shaped conductor foil 1, and the loop-shaped conductor foil 1 is an antenna of the conventional plate-shaped inverted-F antenna shown in FIG. It is formed so as to simulate the operation mode of the element (patch) 11. 11 are denoted by the same reference numerals, and FIG. 2A differs from FIG.
Is replaced by a loop-shaped conductor foil 1 formed in a linear shape. The loop-shaped conductor foil 1 of FIG. 2A is formed of a metal foil such as a copper foil, focusing on the fact that the current flowing around the plate-shaped antenna element 11 determines the directional characteristics of the antenna. It is formed by etching to leave only the metal foil around the antenna element 11 to be formed.
According to the experiment, even if the plate-shaped antenna element 11 is replaced with the loop-shaped conductor foil 1 and converted to a linear antenna structure, the change in the directivity is small.

In the present invention, the loop length of the loop-shaped conductor foil 1 is reduced by deforming a part of the loop-shaped conductor foil 1 to form a reactance loading means, as in the case of the linear antenna. The length is shortened and the antenna is miniaturized. FIG. 2 (b) shows an example of the principle, in which a part of the loop-shaped conductor foil 1 is bent in a zigzag shape to form a zigzag portion 18 so that a loading inductance is formed in this portion. Thus, reactance loading means is formed.

FIG. 1 shows an embodiment employing the principle shown in FIG. 2B, in which a loop formed of a metal foil such as a copper foil is formed on one surface of a dielectric layer 10 formed of a laminated board or the like. The ground conductor 12 formed of a metal foil such as a copper foil on the other side of the conductor foil 1 is laminated. Using a laminated plate having metal foils on both sides, each metal foil is etched to form the loop-shaped conductor foil 1 and the ground conductor 12, whereby a printed antenna can be formed. A pair of through-holes is provided close to the end of the dielectric layer 10, and a conductor is provided on the inner periphery of each through-hole by plating or the like. A grounding portion 2 for grounding one end of the loop-shaped conductor foil 1 to the ground conductor 12 is formed by one of the through holes, and a coaxial cable connection land formed by etching a part of the ground conductor 12 is provided. A power supply portion 3 for connecting the loop-shaped conductor foil 1 to 13 is formed by the other through hole. Further, a conductor plate 16 formed of a ground plate of the device is joined to the ground conductor 12 by means such as soldering. In the printed antenna thus formed as a plate-shaped inverted F-shaped antenna, a part of the loop-shaped conductor foil 1 is bent in a zigzag shape to form a zigzag portion 18 so that a loading inductance is formed. Since the reactance loading means is formed by the above method, the loop length of the loop-shaped conductor foil 1 is shortened to reduce the mounting area of the loop-shaped conductor foil 1, and the dielectric layer 10 serving as a substrate is formed.
Therefore, it is possible to reduce the size of the antenna without having to use a high dielectric constant material as a material of the dielectric layer 10.

FIG. 3 shows another embodiment employing the principle shown in FIG. 2B. In order to further reduce the size of the dielectric layer 10 serving as a substrate, the loop-shaped conductive foil 1 is 10
Is formed by being divided into two surfaces. That is, the dielectric layer 10 is formed in a vertical shape, half patterns 1a and 1b of the loop-shaped conductor foil 1 are provided on each of opposing side surfaces, and through holes are provided at both ends of the dielectric layer 10 and the inside of the through hole is formed. Each half of the pattern 1 is formed by connecting conductor portions 20a and 20b formed around the periphery by plating through holes or the like.
The loop-shaped conductor foil 1 is formed on the dielectric layer 10 by electrically connecting the end portions of a and 1b to each other. On one half pattern 1a, a ground portion 2 and a power supply portion 3 made of a part of the metal foil forming the loop-shaped conductor foil 1 are provided. The printed antenna of FIG. 3 formed in this manner has a claw 21 on the conductor plate 16 constituting the ground plate.
The ground portion 2 is soldered to the nail 21 or the metal foil 2 left on a part of the dielectric layer 10 is provided.
2 and this claw 21 by soldering,
It is fixed to the conductor plate 16. Of course, the dielectric layer 10 can also be fixed to the conductor plate 16 by bonding.
A coaxial cable 14 having a conductor plate 16 pierced therein
Is connected. Also, as in this embodiment, the dimensions and the like can be made precise by forming the grounding portion 2 and the power feeding portion 3 as a planar structure with a part of the metal foil forming the loop-shaped conductor foil 1. In addition, variations in electrical characteristics can be reduced.

FIG. 4 shows another example of the principle of a plate-shaped inverted-F type antenna formed with the loop-shaped conductor foil 1, wherein a part of the loop-shaped conductor foil 1 is bent in a zigzag shape. In addition to forming the reactance loading means with the loading inductance formed by forming the zigzag portion 18, the highest potential portion at the longitudinal end of the loop-shaped conductor foil 1 distant from the grounding portion 2 is widened. Thus, the capacitance loading conductor 23 is formed, and the reactance loading means is also formed by the loading capacitance constituted by the capacitance loading conductor 23.

FIG. 5A shows an embodiment adopting the principle shown in FIG. 4. When the loop-shaped conductor foil 1 is formed on the dielectric layer 10 by etching a metal foil such as a copper foil. A zigzag portion 18 is formed by bending a part of the loop-shaped conductor foil 1 in a zigzag manner, and a part of the loop-shaped conductor foil 1 is widened to form a capacitance-carrying conductor 23 having an L-shaped planar shape. It is. In the printed antenna thus formed as a plate-shaped inverted F-shaped antenna, a zigzag portion 18 is formed on a part of the loop-shaped conductor foil 1 so that a loading inductance is formed and the loop-shaped conductor foil 1 is formed. Of the loop-shaped conductor foil 1 is further shortened since the load capacitance is formed by forming a part of the conductive foil 1 so that the reactance loading means is formed by a combination of the load inductance and the load capacitance. Thus, the mounting area of the loop-shaped conductor foil 1 can be further reduced, and the antenna can be further reduced in size. In the embodiment of FIG. 5 (b), when forming a part of the loop-shaped conductor foil 1 to be wider and forming the capacitance loading conductor 23 into a plane L-shape, the inner edge of the capacitance loading conductor 23 is formed in an arc shape. The area of the capacitance loading conductor 23 is increased to increase the loading capacity.

FIG. 6 shows another embodiment adopting the principle shown in FIG. 4. As in the case of FIG. 3, in order to further reduce the size of the dielectric layer 10 serving as a substrate, the dielectric layer The loop-shaped conductive foil 1 is divided into two surfaces of the dielectric layer 10 by forming the patterns 10 in a vertical shape and providing half patterns 1a and 1b of the loop-shaped conductive foil 1 on each of the opposing side surfaces. It is like that. Pattern 1 for each half
The zigzag portion 18 and the capacitance-carrying conductor 23 are formed on each of a and 1b. In this embodiment, a conductor foil 25 extending from the ground portion 2 is provided on the lower edge of one side surface of the dielectric layer 10. It is provided along. A conductor foil 16 is also provided on the other side surface of the dielectric layer 10 along the lower edge, and connection conductor portions 27a, 27 formed by plating through holes on the inner periphery of the through holes provided in the dielectric layer 10 are provided.
The conductive foils 25 and 26 are electrically connected at b. The printed antenna of FIG. 6 formed in this manner is fixed to the conductor plate 16 by soldering the conductor foils 25 and 26 to the claws 21 cut and raised on the conductor plate 26 constituting the ground plate.

In the embodiment shown in FIG. 7, the comb-shaped electrode portions 28a, 28b are formed on the grounding conductor 4 formed by the capacitance loading conductor 23 and the conductor foils 25, 26 connected to the grounding portion 2, respectively.
28b, and the comb-shaped electrode portions 28a and 28b are inserted and opposed to each other to form a comb-shaped electrode structure,
The capacitance loading is increased. With such a configuration, it is possible to accurately determine the loading capacity.

Next, an example of the antenna characteristics of the actual device prototyped according to the embodiment of FIG. 6 will be described. 820MHz prototype
The dimensions of the modified inverted F-shaped antenna for use are as shown in FIG. 8, and the width × height × thickness = 35 mm × 7 mm × 5 mm of the dielectric layer 10 formed by the printed wiring board, the grounding section 2 and the feeding section 3 Is 1 mm, and the dielectric constant ε of the dielectric layer 10 is
= 3.5. As shown in FIG. 9, a 110 mm × 35 mm conductor plate 16 is attached to the dielectric layer 10 by soldering 29 as an external ground plate. The antenna characteristics of this printed antenna are as shown in FIGS. 10 (a), (b) and (c). FIG. 10A shows the XY plane directivity characteristics, and FIG.
10 (b) shows the YZ plane directivity, and FIG. 10 (c) shows the ZX plane directivity. The peak gain for vertical polarization is -0.7 dB as shown.
D, -1.9 dBD, and -1.4 dBD (all are dipole antenna ratios). The frequency bandwidth defined by VSWR = 2 is 2.3%. 8 (FIG. 9) is different from that of FIG. 11 (FIG. 12) in the size of the conductor plate 16, but from a comparison of data, the directional characteristics for vertically polarized waves are quite similar. As in the case of the present invention, the decrease in the gain is small and the present invention can be applied to a portable wireless device such as a mobile phone. 8, the volume of the dielectric layer 10 is reduced to 1 / 3.7 and the mounting area of the loop-shaped conductor 1 is reduced to 1 / 5.1, respectively, as compared with that of FIG.

[0021]

As described above, the present invention comprises a loop-shaped conductor foil having one end grounded at a ground portion, and a power supply portion connected to the loop-shaped conductor foil in proximity to the ground portion. Since the printed antenna was created by deforming a part of the foil to form reactance loading means,
By using the reactance loading means, the loop length of the loop-shaped conductor foil can be shortened to reduce the mounting area of the loop-shaped conductor foil, and the area of the dielectric layer serving as a substrate can be reduced. Therefore, the outer shape of the antenna can be reduced in size and weight without using a high dielectric constant material as the material for the antenna.

[Brief description of the drawings]

FIG. 1 is a perspective view of one embodiment of the present invention.

FIGS. 2A and 2B show the principle of the antenna of the embodiment, and FIGS. 2A and 2B are schematic diagrams.

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is a schematic view showing another example of the antenna principle.

FIGS. 5A and 5B show an embodiment based on the above antenna principle, and FIGS. 5A and 5B are perspective views, respectively.

FIG. 6 is a perspective view showing another embodiment of the above.

FIG. 7 is a perspective view showing still another embodiment of the above.

FIG. 8 is a perspective view showing dimensions of a prototype actually manufactured according to the embodiment of FIG. 6;

FIG. 9 is a reduced perspective view of the actual machine.

10A and 10B are diagrams showing measured data of antenna characteristics of the above, wherein FIG. 10A shows XY plane directivity, FIG. 10B shows YZ plane directivity, and FIG. 10C shows ZX plane directivity. Each is shown.

11A and 11B show a conventional example, in which FIG. 11A is a perspective view thereof, and FIG. 11B is a schematic view showing the principle of the antenna.

FIG. 12 is a reduced perspective view of the actual machine.

13A and 13B are graphs showing measured data of antenna characteristics of the above, wherein FIG. 13A shows XY plane directivity, FIG. 13B shows YZ plane directivity, and FIG. 13C shows ZX plane directivity. Each is shown.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Loop-shaped conductor foil 2 Grounding part 3 Feeding part 4 Grounding conductor

Continuation of the front page (56) References JP-A-1-316005 (JP, A) JP-A-4-129302 (JP, A) JP-A-5-347509 (JP, A) JP-A-5-259724 (JP) , A) JP-A-6-97725 (JP, A) JP-A-5-327331 (JP, A) JP-A-2-12729 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H01Q 1/24 H01Q 1/38 H01Q 13/08

Claims (4)

(57) [Claims] 1. A loop-shaped conductor foil, one end of which is grounded at a ground portion, and a power supply portion connected to the loop-shaped conductor foil proximate to the ground portion, wherein a part of the loop-shaped conductor foil is deformed. A printed antenna characterized by forming reactance loading means. 2. The printed antenna according to claim 1, wherein a reactance loading means is formed by a loading inductance formed by bending a part of the loop-shaped conductor foil in a zigzag manner. 3. The reactance loading means according to claim 1 or 2, wherein the reactance loading means is formed by a loading capacitance formed by widening a part of the loop-shaped conductor foil at a position distant from the grounding portion. Printed antenna. 4. The reactance loading means is formed by a loading capacitance of a comb structure formed between a part of the loop-shaped conductor foil located at a position distant from the grounding portion and a ground conductor separate from the loop-shaped conductor foil. The printed antenna according to any one of claims 1 to 3, wherein the antenna is formed.