JP2003078336A - Laminated spiral antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To comparatively widen directivity, especially to increase gains. SOLUTION: A laminated spiral antenna consists of a lowermost layer spiral 1 which is formed by etching processing, etc., on a planar substrate 10 made of a dielectric slab, and an upper layer spiral 2 which is positioned one stage higher than an outer circumferential side end of the spiral 1, is directed toward a radiating direction from this position, and is formed on an upper planar substrate 11 made of the material identical to that of the substrate 10. The spirals 1 and 2 are continuously connected and have a plurality of arms respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated spiral antenna having a relatively wide directivity and a high gain.

[0002]

2. Description of the Related Art In recent years, information communication systems utilizing electromagnetic waves in the microwave band, millimeter wave band, etc. have been proposed worldwide, and in particular, the demand for information communication using microwaves is increasing.

Among them, the improvement of the polarization loss of the transmission / reception antenna which occurs in moving communication equipment such as aviation and satellite systems has become an important issue. Therefore, the use of an antenna that uses circular polarization has been actively researched and developed as a solution. Further, there is a spiral antenna as an antenna having a simple structure and satisfying these requirements.

The structure of the conventional printed spiral antenna is a planar spiral antenna in which the spiral antenna is printed on a dielectric substrate. Specifically, FIG.
It is a print type Archimedes spiral antenna shown in. The Archimedes spiral antenna is a spiral antenna having a constant line width and a constant line interval. To radiate circularly polarized waves from this spiral antenna,
A traveling wave current from the feeding point toward the end of the arm must be established, and an outer circumference of one wavelength or more is required to establish the traveling wave current and radiate circularly polarized waves. The power supply to the spiral antenna is performed from the inner end of the arm, and when supplying power, the phase of the signal entering each arm must be shifted by 180 °. That is, balanced feeding must be performed.

The greatest advantage of this planar spiral antenna is that it has a wide band, wide directivity, and no side lobes. However, the gain is low, about 2 [dBi]. The basic characteristics of this conventional technique were examined. The measurement distance was 1.5 m, and the YZ plane was the E plane and the XZ plane was the H plane during the measurement. The measurement result and the simulation result at this time are shown in FIG.
It was shown to. A high frequency electromagnetic field simulator (HFSS), which is a commercially available simulator, was used for the simulation. As a result, good results were obtained for the simulation value and the measurement result in the half-width of the antenna. The full width at half maximum of the antenna was 80 ° and the antenna gain was 1.4 [dBi]. In addition, the axial ratio at the front is 1.4 [dB], indicating that the antenna is operating as a circularly polarized antenna.

[0006]

As described above, although the spiral antenna has a wide directivity, it has a drawback that the gain is low. Therefore, the problems of improvement and improvement for improving the gain are solved. It was expected that a concrete means of doing so would be provided.

[0007]

Therefore, as a result of intensive studies, the inventor has found that the invention includes a lowermost layer spiral formed on a flat substrate made of a dielectric slab by etching or the like, and a lowermost layer spiral. Located one step higher than the outer peripheral side end of the spiral, facing the radial direction from the position, and consisting of an upper layer spiral formed on an upper layer planar substrate of the same material as the planar substrate, and the lowermost layer spiral and the upper layer spiral. By using a laminated spiral antenna or the like that is continuously connected and has a plurality of arms, it is possible to dramatically improve the gain and solve the above problem.

Further, in the above structure, the lowermost layer spiral and the upper layer spiral may be a laminated spiral antenna continuously connected through a via hole, or in the above structure, a plurality of upper layer spirals with the upper layer planar substrate may be provided. By using the laminated spiral antenna formed by continuously connecting each of them, the improvement of the gain can be dramatically improved, and the above problem is solved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The embodiment is a spiral antenna with a ground plate as shown in FIG.
The lowermost layer spiral 1 is formed on a rectangular flat substrate 10 made of a dielectric slab by peeling, melting or removing the metal thin film on the surface by etching or the like. In FIG. 1, the lowermost spiral 1
The number of arms is 2, but it may be a multiple of 2, such as 4, 8 or the like, and is not limited to this number. Furthermore, in FIG. 1, the number of turns for the arm is four, but the number of turns is not limited. Further, the spiral antenna may not have a ground plate.

The upper layer spiral 2 is also formed on the upper layer flat substrate 11 made of the same material as the flat substrate 10 in the same manner as the lowermost layer spiral 1. In particular, the upper layer spiral 2 is connected to the lowermost layer spiral 1 by a metal wire or the like and is continuous. That is, the upper-layer spiral 1 is arranged such that the outer peripheral side of the one arm of the lower-layer spiral 1 is further outside from the outer-peripheral-side end of the arm via the connecting portion (connection line) 3. Is formed similarly to. By punching the via hole 4 in the upper planar substrate 11 at the upper end position of the connecting portion 3, a chip resistor is loaded on the outer end of the arm to serve as a non-reflective end, and energy is absorbed at the end of the arm to generate a reflected wave. It disappears, and only traveling waves exist.
In FIG. 2, there is a space between the flat substrate 10 and the upper flat substrate 11, but the space may be eliminated. The connection part 3 in the case of the structure without the gap may be a welded connection.

Further, it may be similarly formed from the outer peripheral side end of the other arm of the upper layer spiral 2 to the upper layer side through the connecting portion 3. Although the upper layer thereafter is not shown, the upper layer spiral 2 from the third layer is formed on the third layer upper layer flat substrate 11 and the second layer upper layer flat substrate 11 and the second layer upper layer spiral 2. Is configured similarly to.

The power supply structure comprises a power distributor 20 using a microstrip line, and the power distributor 2
0 is configured so that electric power can be uniformly supplied from the inner end of the arm of the lowermost spiral 1. The line length of the power distributor 20 is adjusted so that the phases entering each of the two arms in FIG. 1 are 0 degree and 180 degrees, and power is supplied from the inner end of the arm. Alternatively, power may be supplied from the external end.

[0013]

EXAMPLE This example shows the arm of the lowermost spiral 1.
The number is 2, and the first to second windings of the arm are the flat substrate 10.
The first layer is on top. Also, the 3rd to 4th rolls of the arm are upper layers.
The upper layer spiral 2 of the second layer is formed on the flat substrate 11 to make a total.
The number of turns was 4. Design frequency is 2-3 [GHz], line
1.5 [lambda] with a width of 2 [mm] and an outer circumference of 2 [GHz] ₀When
did. This spiral antenna with ground plate is also etch
It was produced by Power supply method is coaxial from one arm
Power the line and short the other to ground.
It was

The flat substrate 10 and the upper flat substrate 11 are also provided.
The material is DICLAD880. Substrate conditions are dielectric constant εr
Is 2.17, the substrate thickness is 0.762 [mm], the tan δ is 0.00025, and the conductivity is 5.6 × 10 ⁷ [S / m]. A spiral antenna was manufactured using the above substrate.

The measurement was performed using the laminated spiral antenna having the above-mentioned structure. When measuring, the YZ plane is the E plane, the XZ plane is the H plane, and the measurement results at 2 [GHz]
(experiment) and a simulation result (simulated) are shown in FIG. 3 as an E-plane antenna pattern. As a result, good results can be obtained for the simulation value and the measurement result in the half width of the antenna. Half-width of the antenna is 70
The gain was 2.4 [dBi]. From this result, the conventional printed spiral antenna (see Fig. 5)
Compared with, the antenna half width is 10 ° narrower and the gain is 1 [dBi].
I was able to improve. The axial ratio at the front is 1.84 [dBi]
Therefore, it can be seen that it operates as a circularly polarized wave antenna like the conventional printed spiral antenna.

The laminated spiral antenna of the present invention has a wide band like the conventional spiral antenna and has no side lobe. Further, by adopting a laminated structure, the directivity is slightly narrowed, but the greatest advantage is that the gain can be improved. With this configuration,
Stacking spiral antenna of the present invention is a broadband, directivity is wider than the other antenna, also receive information from any direction for a circular polarized wave, because there is no polarization loss due to antenna, FIG. 4 It is considered that the antenna is suitable for the indoor wireless LAN as shown in FIG.

[0017]

According to the present invention, since the spiral antenna structure is formed by stacking layers, not only the directivity is relatively wide, but also the greatest advantage that the gain can be made higher than that of the conventional planar spiral antenna is provided. is there.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is an E-plane antenna pattern diagram of the present invention.

FIG. 4 is a conceptual diagram of a use example of the present invention.

FIG. 5 is a schematic perspective view of a conventional spiral antenna.

FIG. 6 is an E-plane antenna pattern diagram of a conventional spiral antenna.

[Explanation of symbols]

1 ... Bottom spiral 2 ... Upper spiral 4 ... Via hole 10 ... Flat substrate 11 ... Upper planar substrate

Claims (3)

[Claims] 1. A lowermost layer spiral formed by etching or the like on a flat substrate made of a dielectric slab, and one step above the outer peripheral side end of the lowermost layer spiral, and from the position toward the radial direction, And consisting of the upper layer spiral formed on the upper layer flat substrate of the same material as the flat substrate,
The laminated spiral antenna, wherein the lowermost layer spiral and the upper layer spiral are continuously connected and each has a plurality of arms. 2. The laminated spiral antenna, wherein the lowermost spiral and the upper spiral are continuously connected via a via hole. 3. The laminated spiral antenna according to claim 1, wherein a plurality of upper layer spirals with the upper layer planar substrate are provided and are connected in succession.