WO2001006596A1

WO2001006596A1 - Dielectric antenna

Info

Publication number: WO2001006596A1
Application number: PCT/JP1999/006154
Authority: WO
Inventors: Yuji Masumoto; Hirofumi Yamaguchi; Futoshi Kuroki
Original assignee: Nippon Tungsten Co., Ltd.
Priority date: 1999-07-19
Filing date: 1999-11-04
Publication date: 2001-01-25
Also published as: WO2001006596A8

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. 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 wave, quasi-microwave, microwave, and millimeter wave. 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. H10-247807, Japanese Patent Application Laid-Open No. H10-303612. And a ground electrode and a feed terminal formed on the bottom surface of the dielectric, and a strip-shaped antenna electrode formed on the top surface of the dielectric is formed. In addition, the feeder terminal and the antenna electrode are connected through the inside of the dielectric, and the use of the dielectric as the main radiating element reduces the decrease in antenna efficiency due to the increase in frequency. It is an improvement. 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 a side surface of the dielectric, wherein the planar dielectric is formed of a ceramic having a high dielectric constant; and A band-shaped antenna electrode on the top surface of a planar dielectric is formed in a spiral shape.

The ceramics having a high dielectric constant, B a T I_〇 ₃ system I _r has 3 0-1 2 0 about _{permittivity, B a (M g 1/} 3 T a 2, 3) 0 3 system, Seramittasu such _{B a (Z n 1/3} T a 2 c) 〇 ₃ system can be preferably used. As a result, the antenna can be downsized due to the wavelength shortening effect of the dielectric ceramics having a high dielectric constant. Also, by forming the strip-shaped antenna electrode in a spiral shape, radio waves can be radiated in all directions and omnidirectionality can be achieved.

Also, in order to reduce the size in the low frequency band below the quasi-microwave, a high-dielectric constant dielectric material such as alumina or epoxy resin should have a low dielectric constant thin layer (Er) of about 2 to 10 (several layers). Um) can cover a wide range of frequency bands.

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

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, performs matching at a desired frequency by connecting a matching element such as an inductor coil or a capacitor to a feed terminal thereof. Can be taken. Simply, this matching element can be formed integrally with the antenna electrode on the dielectric substrate.

Here, in the present specification, the “spiral shape” refers to a shape drawn in a one-stroke shape from the outside of the quadrilateral to the inside with a line segment parallel to the four sides of the quadrilateral. The corners connecting the line segments are not necessarily right angles but may be formed by arcs. The strip-shaped electrodes formed by line segments parallel to these four sides make it possible to generate radio waves in four directions parallel to the surface of the dielectric substrate and in six directions perpendicular to the surface of the dielectric substrate, that is, in all directions. Is 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 FIGURES

FIG. 1 shows a first embodiment of the present invention, and shows a dielectric antenna in which a strip-shaped electrode on a 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 a dielectric antenna in which dielectrics are stacked, and shows a current distribution on an antenna 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 surface of a dielectric antenna in which dielectrics are stacked.

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

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 illustrating 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 is a diagram showing the second embodiment.

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

FIG. 11 shows a case where power is supplied using a microstrip line in the method of feeding a dielectric antenna according to the present invention.

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

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.

■ Figure 1 shows a first embodiment of the present invention, using a cell • ceramic substrate 1 of a high dielectric constant (f _r = 9 0), the strip-shaped antenna electrode 2 on one side of the ceramic substrate 1 5 3 shows a dielectric antenna formed in a spiral shape. 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-side) 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, antenna electrodes are provided on both surfaces of one dielectric ceramic substrate 1 as in the embodiment of FIG. 2 is formed, and both antenna electrodes are connected via the side electrode 3 in the figure. When unbalanced power is fed 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 becomes maximum and minimum on the side electrode 3 at the midpoint 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, and Fig. 3 shows the current distribution of the lowest mode. The frequency at which these modes operate as antennas is when the effective length of the antenna is an integral multiple of half a wavelength, and the operating frequencies are fe and f. Then f _e =

0

f: '

It is represented by. Here, the physical length of the antenna is L, and the effective dielectric constants of the even and odd symmetric modes are _{f ee} and ε _e , respectively. , And the speed of light C. And As can be seen from this formula, if the even symmetric mode shown in Fig. 3 (a) can be excited in the antenna structure of Fig. 2 as shown in Fig. 5, a small and thin antenna can be realized even in the frequency band below the quasi-mic mouthwave.

By the way, in Fig. 3, focusing on the electric force-line and 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 behaves as a magnetic wall, and in odd-symmetric mode, this surface behaves as an electric wall. Therefore, in the frequency band below the quasi-microwave, in a double-sided antenna electrode using a ceramic substrate with a thickness of several mm at most, the coupling between the antenna electrodes becomes strong, and the odd symmetric mode in Fig. 4 (b) is dominant. Becomes Also, in order to excite the even symmetric mode, the ceramic substrate had to be sufficiently thick, which was a factor that hindered miniaturization and thinning of the antenna.

Therefore, in the present invention, as shown in FIG. 2, a thin low dielectric constant of about several tens of μm (£ _r = 2) is provided between two ceramic substrates 1 and 1 ′ each having antenna electrodes 2 and 2 ′ formed on one side, respectively. 10) and a side electrode 3 connecting the upper and lower antenna electrodes 2 and 2 ′ is provided on the side surface of the dielectric antenna. As a result, when the low dielectric constant side is viewed from the ceramic substrate side, the interface between the high / low dielectric constant layers becomes closer to the magnetic wall as the difference between the relative dielectric constants of the two increases. Even in the case of using a thin ceramic substrate as in c), even-symmetric mode excitation is possible, and a small and thin dielectric antenna can be obtained even in the frequency band below the quasi-microwave.

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, so that the antenna characteristics can be easily improved. be able to.

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 has a capacitance component, the inductor (coil 6) This shows the former case of installing a capacitor if it is an inductor component.

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

FIG. 8 shows the results of measuring the frequency and the return loss characteristics in the first embodiment by preparing prototypes of samples 1 to 6 having different sizes of the ceramic substrate and electrode patterns. Table 1 shows the measurement results. Sample 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 5.31

④ 5 X 5 X 1 1 900-1 8.29

⑤ From the result of 5 X 5 X 1 2400-30.00, it can be seen that each sample works well 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 is understood that a small dielectric antenna functions as an antenna even in a low frequency band of 200 to 400 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 method of feeding a dielectric antenna according to the present invention, in which power is fed using nine microstrip lines.

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) formed of a planar dielectric ceramic having a high dielectric constant, and

-The strip-shaped antenna electrode on the top surface of the planar dielectric is formed in a spiral shape;

5 allows omnidirectionality to be achieved with a small dielectric antenna.

(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 improve antenna characteristics.

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

0 (4) Further, 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, achieves matching by connecting an inductance coil or a capacitor to its feeding terminal. Can be.

• Industrial availability

5 The present invention can be used in the manufacture of a dielectric antenna used for wireless communication.

0

Five

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.