JPH06152225A - Spiral antenna - Google Patents

Abstract

PURPOSE:To obtain a wider radiation directive characteristic. CONSTITUTION:In order to couple a dielectric board 3 with spiral radiation elements 2a, 2b formed thereon, an outer ridge of the dielectric board 3 is fixed to a cavity 4 by a ring member via a radio absorbing member 6 to form the spiral antenna 11. The ring member is made of a dielectric body and formed by a torus dielectric member 12 whose cross section is nearly 3/4 circle or a 3/4 ellipse and the torus dielectric member 12 is loaded onto the radiation elements 2a, 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral antenna,
In particular, it relates to a spiral antenna having a wide radiation directivity characteristic.

[0002]

2. Description of the Related Art Conventionally, as a spiral antenna of this type,
For example, there is one shown in a perspective view of FIG. In FIG. 1, a spiral antenna 1 has a dielectric substrate 3 having spiral radiating elements 2a and 2b formed on its surface, placed on an opening of a cavity 4, and the outside of the dielectric substrate 3. The periphery of the dielectric substrate 3 is bonded and bonded to the cavity 4 by an adhesive ring member 5 made of a lossy dielectric having an L-shaped cross section.

When the dielectric substrate 3 is joined to the cavity 4, a radio wave absorber 6 is applied to the joint surface between the outer peripheral edge portion of the dielectric substrate 3 and the adhesive ring member 5, and the electric wave absorber 6 is applied on the substrate 3. The electric currents flowing in the spiral radiating elements 2a, 2b are absorbed at the ends of the radiating elements 2a, 2b.

[0004]

However, in the conventional spiral antenna 1 as described above, it is difficult to greatly change the characteristics in order to obtain the required radiation directivity characteristics.

That is, with respect to the radiation directivity characteristic of the spiral antenna 1, the position where strong radiation occurs is automatically determined by the self-adjusting action of the current flowing through the radiating elements 2a and 2b. There is a problem that it cannot be applied to characteristics other than the characteristics, especially to fields requiring wider radiation directivity characteristics.

The present invention has been made in view of the above points,
It is an object of the present invention to solve the above problems and provide a spiral antenna that can obtain a wider radiation directivity characteristic.

[0007]

In order to achieve the above object, the structure of the present invention is such that an outer edge portion of a dielectric substrate on which a spiral radiating element is formed is coupled to a cavity. A spiral antenna fixed to the cavity by a ring member via a radio wave absorber is as follows.

(1) The ring member is an annular dielectric member which is made of a dielectric material and has a cross section of approximately 3/4 circular or 3/4 oval, and the radiating element is provided with the annular dielectric member. It is characterized by being loaded.

(2) The inside of the annular dielectric member in (1) above is characterized by having an arbitrary cross-sectional shape.

(3) The ring member is made of a dielectric material having an L-shaped cross section, and an outer annular dielectric member having a substantially 3/4 circular or 3/4 oval cross section outside the ring member. And the outer annular dielectric member is loaded on the radiating element.

[0011]

[Operation] In the spiral antenna configured as described above, the radiation directivity characteristic is largely changed by selecting the cross-sectional shape, size and dielectric constant of the annular dielectric member or the outer annular dielectric member. In addition, it is possible to obtain a required wide radiation directivity characteristic.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be exemplarily described in detail below with reference to the drawings.

(First Embodiment) FIG. 1 is a partially sectional perspective view showing a first embodiment of a spiral antenna according to the present invention. The same members as those in FIG. 5 are designated by the same reference numerals and their description is omitted. .

In FIG. 1, the spiral antenna 11 is shown in FIG.
In place of the adhesive ring member 5 shown in FIG. 3, an outer peripheral edge portion of the dielectric substrate 3 is formed by an annular dielectric member 12 made of a dielectric material and having a substantially 3/4 circular cross section (a fan shape having a central angle of about 270 degrees). Is coupled to the cavity 4 and the spiral radiating element 2
The annular dielectric member 12 is loaded on a and 2b.
The cross section of the annular dielectric member 12 is not limited to a circular shape, but may be an elliptical shape or a polygonal shape, and a range of about 90 degrees occupied by the dielectric substrate 3 and the cavity 4 to be joined is cut out.

Radiating elements 2a, 2 of the spiral antenna 11
The radio wave radiated from b has a region (wide-angle region) that passes through the annular dielectric member 12 and a region (front region) that does not pass through it.
Can be divided into

In the region where the radio wave passes through the inside of the annular dielectric member 12, the wavelength shortening action by the dielectric of the dielectric member 12, reflection on the dielectric surface, refraction action and reflection inside the dielectric substance, refraction action. Occurs.

From these actions, the spiral antenna 11
The electromagnetic field distribution on the aperture plane of is changed in a wide angle range, and as a result, the radiation pattern having a wide far field is provided. In addition, the cross-sectional shape and size of the annular dielectric member 12 and the permittivity of the dielectric can be changed to change the electromagnetic field distribution on the opening surface of the spiral antenna 11 and, as a result, the radiation directivity characteristics. it can.

(Second Embodiment) FIG. 2 is a partially sectional perspective view showing a second embodiment of the present invention, which is a modification of FIG. 2, the annular dielectric member 22 of the spiral antenna 21 is made of a dielectric material, and its sectional shape is a partial deformation of the annular dielectric member 12 shown in FIG. A portion 22b formed by 22a and the surface of the dielectric substrate 3 is added, and the joint surface with the dielectric substrate 3 is fixed to the dielectric substrate 3.

The added portion 22b of the annular dielectric substrate 22 is not limited to the sectional shape shown in FIG. 2, and may have an arbitrary sectional shape.

Since the ring-shaped dielectric member 22 is loaded on the radiating elements 2a and 2b, the radiation of the spiral antenna 21 depends on the shape and size of the added portion 22b of the ring-shaped dielectric member 22. The directivity can be adjusted to a desired directivity.

(Third Embodiment) FIG. 3 is a partially sectional perspective view showing a third embodiment of the present invention. The same members as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 3, a spiral antenna 31 is formed on the outside of the adhesive ring portion 5 made of a dielectric material having an L-shaped cross section which constitutes the conventional spiral antenna 1, and is made of a dielectric material having a substantially 3/4 circular cross section. The outer annular dielectric member 32 is fixed and the radiating elements 2a and 2b are loaded with the outer annular dielectric member 32.

The cross-sectional shape of the outer annular dielectric member 32 is not limited to a circular shape, but may be an elliptical shape or a polygonal shape, and a range of about 90 degrees occupied by the adhesive ring member 5 to be fixed is cut out.

The spiral antenna 31 can adjust its radiation directivity to a desired directivity depending on the shape and size of the outer annular dielectric member 32 and the permittivity of the dielectric.

FIG. 4 shows a spiral antenna 31 according to this embodiment.
FIG. 8 is a comparison diagram of radiation directivity characteristics (indicating a radiation attenuation amount with respect to a radiation angle) between the conventional spiral antenna 1 and the conventional spiral antenna 1. As is clear from the figure, the outer ring-shaped dielectric member 32 of the present embodiment.
The radiation directivity characteristic of the spiral antenna 31 is smaller than that of the conventional one, and the variation of the attenuation amount is small over a wide radiation angle, and the wide radiation directivity characteristic is obtained.

The technique of the present invention is not limited to the technique in the above-described embodiment, and means of another aspect having a similar function may be used, and the technique of the present invention is various within the scope of the above configuration. Can be changed or added.

[0027]

As is apparent from the above description, according to the spiral antenna of the present invention, the dielectric substrate having the spiral radiating element is fixed to the ring member for coupling to the cavity or to the outside thereof. Since the outer member to be used is an annular dielectric member having a substantially 3/4 circular shape or a 3/4 elliptical cross section, and the radiating element is loaded with each of the annular dielectric members, By selecting the cross-sectional shape, size and its dielectric constant, various wider radiation directivity characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a partially sectional perspective view showing a first embodiment of a spiral antenna according to the present invention.

FIG. 2 is a partially sectional perspective view showing a second embodiment of the present invention.

FIG. 3 is a partially sectional perspective view showing a third embodiment of the present invention.

FIG. 4 is a comparison diagram of respective radiation directivity characteristics (showing a radiation attenuation amount with respect to a radiation angle) between the spiral antenna 31 according to the third embodiment and the conventional spiral antenna 1.

FIG. 5 is a partially sectional perspective view showing a conventional spiral antenna.

[Explanation of symbols]

 1,11,21,31 spiral antenna 2a, 2b radiating element 3 dielectric substrate 4 cavity 5 adhesive ring member 6 radio wave absorber 12,22 annular dielectric member 32 outer annular dielectric member

Claims (3)

[Claims] 1. An outer edge portion of a dielectric substrate having a spiral radiating element formed thereon for coupling to a cavity,
A spiral antenna fixed to the cavity by a ring member via a radio wave absorber, wherein the ring member is made of a dielectric material and has a cross section of approximately 3/4 circular or 3/4 oval annular dielectric. A spiral antenna comprising a body member, wherein the radiating element is loaded with the annular dielectric member. 2. The spiral antenna according to claim 1, wherein the inside of the annular dielectric member has an arbitrary cross-sectional shape. 3. A dielectric substrate on which a spiral radiating element is formed is coupled to a cavity so that an outer edge portion of the dielectric substrate is formed.
A spiral antenna fixed to the cavity by a ring member via a radio wave absorber, wherein the ring member is made of a dielectric material having an L-shaped cross section, and the cross section is approximately 3/4 yen outside the ring member. A spiral antenna, wherein an outer annular dielectric member having a shape or a 3/4 oval shape is fixed, and the radiating element is loaded with the outer annular dielectric member.