WO2001033669A1

WO2001033669A1 - Dielectric antenna

Info

Publication number: WO2001033669A1
Application number: PCT/JP1999/006155
Authority: WO
Inventors: Yuji Masumoto; Hirofumi Yamaguchi; Futoshi Kuroki
Original assignee: Nippon Tungsten Co., Ltd.
Priority date: 1999-11-04
Filing date: 1999-11-04
Publication date: 2001-05-10

Abstract

The invention provides a small dielectric antenna having good mountability and unlikely to deteriorate its performance. The dielectric antenna includes feeder terminals (3, 4) attached to the lower surface or a side of a flat dielectric material (1). A striplike antenna electrode (2) is formed on the upper surface of the dielectric material (1). The feeder terminals (3, 4) and the antenna electrode (2) are connected within or through the side of the dielectric material (1). The dielectric material (1) is formed of ceramic, and the striplike antenna electrode (2) is formed in a spiral.

Description

Specification

Dielectric antenna

Technical field

The present invention relates to a dielectric antenna used for wireless communication of ultrashort waves, quasi-microwaves, microwaves, and millimeter waves. Background art

Such a dielectric antenna is disclosed in, for example, Japanese Patent Application Laid-Open No. H10-174334, Japanese Patent Application Laid-Open No. A block-shaped or planar dielectric disclosed in Japanese Patent Application Laid-Open No. 0-247807 and Japanese Patent Application Laid-Open No. Hei 10-33612, and a ground formed on the bottom surface of the dielectric. An electrode and a power supply terminal are formed, a strip-shaped antenna electrode formed on the upper surface of the dielectric is formed, and the power supply terminal and the antenna electrode are connected through the inside of the dielectric. The use of a dielectric material as the main radiating element has improved the decrease in antenna efficiency due to the increase in frequency. However, conventional dielectric antennas have many issues that need to be improved.

For example, conventional dielectric antennas have a problem that they are not suitable for surface mounting because the power supply terminal is located in the center of the back surface. In this case, the performance is degraded due to the influence of the lines of electric force due to the proximity of the antenna electrodes, and furthermore, it is difficult to match each frequency range due to the frequency characteristics of the antenna. Disclosure of the invention

The problem to be solved by the present invention is to solve the above-mentioned problems in the conventional dielectric antenna and to prevent the performance degradation as a dielectric antenna while being excellent in mountability and small in size.

In the dielectric antenna of the present invention, a feeding terminal is provided on a bottom surface or a side surface of a dielectric formed in a planar shape, and a band-shaped antenna electrode is formed on an upper surface of the dielectric. A feed terminal and an antenna electrode are connected through the inside or the side surface of the dielectric. In the dielectric antenna, the planar dielectric is formed of ceramics having a high dielectric constant. Further, the band-shaped antenna electrode on the top surface of the planar dielectric is formed in a spiral shape.

5 As a ceramic having a high dielectric constant, a Ba T i〇3 system having a dielectric constant of ε _r of about _{30 to} 120, Ba (M g! / ₃ T a _2/3 ) 0 ₃ _{system, B a (Z n 1/} 3 T a 2/3). 0 such ₃ based ceramics can be preferably used. This makes it possible to reduce the size of the antenna due to the wavelength shortening effect of the dielectric ceramic having a high dielectric constant. -In addition, by forming the strip-shaped antenna electrode in a spiral shape, radio waves can be radiated in all directions 0 and omnidirectionality can be achieved.

In addition, in order to reduce the size in the low frequency band below the quasi-microwave, a dielectric material having a high dielectric constant, such as alumina or epoxy resin, has a low dielectric constant of ε _r of about 2 to 10. By laminating through layers (several tens / zm), it is possible to cover a wide range of frequency bands.

5 Furthermore, by attaching a dielectric substrate to the bottom surface of the laminated dielectric antenna or the single-sided spiral dielectric antenna, frequency adjustment and matching can be achieved, thereby improving the characteristics of the antenna.

-Further, according to the present invention, the dielectric antenna in which the strip-shaped antenna electrode on the upper surface of the dielectric is formed in a spiral shape.

By connecting 20 matching elements, matching at a desired frequency can be achieved. Simply, this matching element can be formed integrally with the antenna electrode on the dielectric substrate.

Here, in this specification, the “spiral shape” refers to a shape drawn in a single stroke from the outside to the inside of the quadrilateral with a line segment parallel to the four sides of the quadrilateral. Say The corners connecting the line segments are not necessarily right angles but are formed by arcs.

25 The strip-shaped electrodes formed by line segments parallel to the four sides allow four directions parallel to the plane of the dielectric substrate and two directions perpendicular to the surface of the dielectric substrate, that is, in all directions. Radio waves are radiated and can be received. In other words, it becomes an omnidirectional antenna. In addition, “spiral” refers to a simple spiral that has no linear portion. -Also refers to things.

• Brief description of the drawing

FIG. 1 shows a first embodiment of the present invention, and shows a dielectric antenna in which a strip-shaped antenna electrode on the top surface of a dielectric is formed in a linear spiral shape.

FIG. 2 shows a second embodiment of the present invention, and shows an example in which a dielectric is laminated via a thin layer having a low dielectric constant.

-Fig. 3 is a diagram for explaining the effect of the dielectric antenna having the dielectric layered, and shows the current distribution on the antenna and the electrode.

FIG. 4 is a diagram illustrating the effect of a dielectric antenna in which dielectrics are stacked.

FIG. 5 shows an example in which a dielectric substrate is further attached to the bottom of a dielectric antenna in which a dielectric is laminated.

FIG. 6 shows an example of connecting a coil to achieve matching at a desired frequency in the dielectric antenna of the present invention.

5 FIG. 7 shows an example in which a coil is integrated with an antenna electrode on a dielectric substrate in order to achieve matching at a desired frequency in the dielectric antenna of the present invention.

-FIG. 8 is a diagram showing an example of samples 1 to 6 in which the size of the dielectric ceramic substrate and the electrode pattern are different in the first embodiment.

FIG. 9 shows a second embodiment.

0 FIG. 10 shows a case where power is supplied using a coplanar line in the method for feeding a dielectric antenna according to the present invention.

-Fig. 11 shows the method of feeding a dielectric antenna according to the present invention.

• Shows when power is supplied using.

-FIG. 12 shows the case where the feeding method for the dielectric antenna according to the present invention is performed using a coaxial line 5.

-Fig. 13 shows a method of feeding a dielectric antenna according to the present invention, in which a slot is not used and power is fed from a back surface-using a coplanar line by electromagnetic coupling. -Best mode for carrying out the invention

An embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the invention, in which a high dielectric constant (= 90)

• This shows a dielectric antenna in which a band-shaped antenna electrode 2 is formed in a 5-spiral shape on one side of a ceramic substrate 1 using a ceramic substrate 1. By making the shape of the antenna electrode 2 spiral, it becomes non-directional. By feeding power to the (side-to-side) electrode 3 or the (bottom) electrode 4 in microwaves and millimeter waves, a small and lightweight antenna with excellent characteristics can be obtained.

FIG. 2 shows a second embodiment of the present invention. In order to reduce the size of the antenna, as shown in the embodiment of FIG. 1, antenna electrodes are provided on both surfaces of one dielectric ceramic substrate 1. 2 is formed, and both antenna electrodes are connected via the side electrode 3 in the figure. When unbalanced power is supplied from the center of the upper antenna electrode in this structure, the current distribution on the antenna is roughly divided into modes in which the current is maximum and minimum on the side electrode 3 which is the middle point of the antenna. Here, the former is called the even symmetric mode, and the latter is called the odd symmetric mode. 5 These modes are further subdivided according to the resonance order. Figure 3 shows the current distribution of the lowest mode. The frequency at which these modes operate as an antenna is when the effective length of the antenna is an integral multiple of half a wavelength, and each operating frequency is f f. Then 0 2

. f

ΛΙ

-Is represented by Where the physical length of the antenna is L, the effective dielectric of even and odd symmetric modes

• Rate each £. , And light speed C. And As you can see from this equation

If the even symmetric mode shown in Fig. 3 (a) can be excited in the antenna structure of Fig. 2 in Fig. 25,

• A small and thin antenna can be realized even in the frequency band below the mouthpiece.

By the way, in Fig. 3, the electric force and the current distribution on the # 1-# 1 'plane of the even and odd symmetric modes. As shown in Fig. 4, they are related to the even symmetric mode. In the figure, the # 2— # 2 'surface becomes a magnetic wall, and in odd-symmetric mode, this surface becomes an electrical wall. Therefore, in the frequency band below the quasi-microwave,

• In a double-sided antenna electrode using a ceramic substrate of about mm, the coupling between the antenna electrodes becomes strong, and the odd-symmetric mode in Fig. 4 (b) becomes dominant. Also, in order to excite the even-symmetric five modes, the ceramic substrate had to be sufficiently thick, which was a factor that hindered the miniaturization and thinning of the antenna.

Therefore, according to the present invention, as shown in FIG. 2, a thin low dielectric constant of about several tens m is provided between two ceramic substrates 1, 1 each having antenna electrodes 2, 2 'formed on one side thereof. ί _r = 1 0 about) to and side surfaces of the dielectric antenna provided with a layer 5 of providing the side electrodes 3 that connects the upper and lower antenna 0 Na electrodes 2, 2 '. By doing so, the ceramic

-When the low dielectric constant side is viewed from the side of the backing substrate, the interface between the high-Z low-dielectric layer becomes closer to the magnetic wall as the difference in relative dielectric constant between them increases. Even thin-ceramic substrate enables even-symmetric mode excitation, and a small and thin dielectric antenna can be obtained even in the frequency band below quasi-microwave.

15 FIG. 5 shows that the dielectric substrate 6 is attached to one surface of the dielectric antenna according to the first embodiment or the second embodiment so that frequency adjustment and matching can be achieved, thereby improving the antenna characteristics. It can be easily achieved.

FIG. 6 shows that in the dielectric antenna of the present invention, in order to obtain matching at a desired frequency other than the method of FIG. 5 described above, according to the Smith chart, if the dielectric antenna 20 has a capacitance component, the inductor ( The former shows the case of installing a capacitor if the coil 6) is an inductor component.

FIG. 7 shows a case where the inductor (coil) 7 as a matching element is formed integrally with the antenna electrode 2 on the dielectric substrate 6 by the method of FIG. 6 above in the dielectric antenna of the present invention. I have.

25 FIG. 8 shows the results of measuring the frequency and the return loss characteristics of the first embodiment in which samples of (1) to (4) having different ceramic substrate sizes and electrode patterns were prototyped. Table 1 shows the measurement results. No. size (mm) Frequency (MHz) Return loss (dB)

① 1 0 X 1 0 X 1 800-32.23

② 1 0 X 1 0 X 1 90 0 -33.55

③ 5 X 5 X 1 1 500-1 5.3 1

④ 5 X 5 X 1 1 900-1 8.29

⑤ 5 X 5 X 1 2400-30.00 These results show that each sample functions as an antenna in the band from 800 MHz to 2.4 GHz.

FIG. 9 shows the second embodiment, in which samples of ① to の having different electrode patterns are prototyped, and the frequency and the return loss characteristics are measured. Table 2 shows the measurement results.

Table 2

From this result, it can be seen that a small dielectric antenna functions as an antenna even in the low frequency band of 200 to 40 MHZ.

FIG. 10 shows a case where power is supplied using the coplanar line 8 in the method of feeding a dielectric antenna according to the present invention.

FIG. 11 shows a case where power is supplied using nine microstrip lines in the method for supplying a dielectric antenna according to the present invention.

FIG. 12 shows a case where power is supplied using the coaxial line 10 in the method for feeding a dielectric antenna according to the present invention.

Fig. 13 shows the method of feeding a dielectric antenna according to the present invention. The case where power is supplied using the planar line 11 is shown.

As described above, the present invention has the following effects.

(1) Since it is formed of a planar dielectric ceramic having a high dielectric constant and the strip-shaped antenna electrode on the upper surface of the planar dielectric is formed in a spiral shape, it is omnidirectional with a small-sized dielectric antenna. Can be achieved.

(2) By laminating a dielectric having a high dielectric constant via a thin layer having a low dielectric constant, it is possible to cope with a wide frequency band, and the antenna characteristics are improved.

(3) Further, by attaching a dielectric substrate to the bottom surface of the laminated dielectric antenna, frequency adjustment and matching can be easily achieved.

(4) Furthermore, the dielectric antenna according to the present invention, in which the strip-shaped antenna electrode on the upper surface of the dielectric is formed in a spiral shape, can achieve matching by connecting an inductance coil or a capacitor to its feeding terminal. Industrial applicability

INDUSTRIAL APPLICATION This invention can be utilized in manufacture of the dielectric antenna used for wireless communication.

Claims

The scope of the claims

1. A feed terminal is provided on the bottom or side surface of the dielectric formed in a plane, and a strip-shaped antenna electrode is formed on the upper surface of the dielectric. Further, the feed terminal and the antenna electrode are formed inside the dielectric. Alternatively, in the dielectric antenna connected through a side surface, the planar dielectric is formed of ceramics having a high dielectric constant, and the band-shaped antenna electrode is formed in a spiral shape.

2. The dielectric antenna according to claim 1, wherein a dielectric formed in a planar shape is laminated via a thin layer having a low dielectric constant.

3. The dielectric antenna according to claim 1, further comprising a dielectric substrate attached to the bottom surface.

4. The dielectric antenna according to claim 1, wherein a matching circuit such as a coil or a capacitor is formed integrally with the antenna on the power supply terminal surface on the dielectric substrate.

5. Claims 1 to 5 in which the feeding means can be a coplanar line, a microstrip line, a coaxial line on the same plane as the antenna electrode, or a coplanar, microstrip, or coaxial feed from the back side of the antenna electrode. 4. The dielectric antenna according to any one of 4.