JP2002094322A - Spiral antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of the conventional spiral antenna that has had a narrower beam width, because the conventional spiral antenna employs a cavity whose bottom face has a planar structure. SOLUTION: The spiral antenna of this invention adopts a cavity bottom face having ruggedness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral antenna having a wide band characteristic.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing the configuration of a conventional spiral antenna, wherein 1 is a dielectric substrate, 2 is a spiral conductor formed on the dielectric substrate 1, and 3 is a spiral conductor 2
4 is a microstrip taper balun connected to the parallel two-wire line 3, 5 is a coaxial connector connecting the microstrip taper balun 4 to the outside of the antenna, and 6 is the microstrip balun 4 7 is a conductor in the coaxial connector connected to the microstrip line of the microstrip line.
Is a coaxial connector outer conductor connected to the ground conductor, 8 is a cavity, and 9 is a structure holding the dielectric substrate 1 and the coaxial connector 5.

FIG. 5 is a view showing a radiation mode of the conventional spiral antenna shown in FIG. 4, in which 2 is a spiral conductor, 10 is the circumference of the conductor, 11 is the bottom surface of the cavity, and 12 is radiated to the surface of the spiral conductor 2. 13 is a microwave radiated to the cavity side, and 14 is a microwave reflected from the cavity bottom surface 11.

FIG. 6 is a view showing a radiation mode of microwaves radiated to the cavity side in the spiral antenna of the conventional configuration shown in FIG. 4, wherein 1, 2, 8, 9, 11, 1
2, 13, and 14 are the same as those in FIGS.

Next, the operation will be described with reference to the drawings. In the conventional configuration shown in FIG. 4, the microwave supplied to the coaxial connector 5 is supplied to the parallel two-wire line 3 connected to the microstrip taper balun 4 via the microstrip taper balun 4 connected to the coaxial connector 5. Is transmitted from the coaxial transmission mode to the parallel two-wire transmission mode.

The microwave converted to the parallel two-wire transmission mode is supplied to the two spiral conductors 2 connected to the parallel two-wire line 3 in opposite phases, and has a circumference of 10 mm as shown in FIG. Spiral conductor 2 at a frequency at which
The microwaves 12 radiated to the front and back of the spiral conductor 2 and radiated to the front of the spiral conductor 2 are radiated to the space as they are.

[0007] Microwave 13 radiated to the cavity side
Is reflected by the cavity bottom surface 11 and part of the microwave 14 reflected by the cavity bottom surface 11 passes through the spiral conductor 2 and is re-emitted, and another part of the reflected microwave 14 is the spiral conductor 2 To excite and re-emit the current.

In the spiral conductor 2, microwaves are radiated at a frequency at which the wavelength of the microwave fed from the connector ranges from the minimum circumference to the maximum circumference of the spiral conductor 2, so that the antenna device has a wide band.

At this time, as shown in FIG. 6, the microwave 13 radiated toward the cavity has a cavity bottom surface 11 having a planar structure parallel to the spiral conductor 2 and the dielectric substrate 1 constituting the spiral conductor 2. It is reflected perpendicular to the cavity bottom. Therefore, a part of the microwave 14 reflected at the bottom of the cavity passes through the space between the spiral conductors 2 and is re-emitted, so that the radiation gain increases in front of the spiral conductor, but the radiation gain in the wide-angle direction increases. descend.

[0010]

The conventional spiral antenna has a problem that the beam width is narrow because the bottom surface of the cavity portion uses a cavity having a planar structure.

The present invention has been made to solve the above-described problems, and has as its object to widen the beam width of a spiral antenna in a wide angle direction.

[0012]

A spiral antenna according to a first aspect of the present invention has a plurality of projections provided on a bottom surface of a cavity portion.

A spiral antenna according to a second aspect of the present invention comprises:
The bottom surface of the cavity portion is a bottom surface having a curved surface protruding in the spiral conductor direction.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram of a spiral antenna according to a first embodiment of the present invention, and 1, 2, 3, 4, 5, 6, and 7.8 are the same as the conventional spiral antenna. In FIG. 1, reference numeral 11 denotes a cavity bottom surface, and 15 denotes a projection provided on the cavity bottom surface 11.

Next, the operation of the spiral antenna will be described. In FIG. 1, the microwave supplied to the coaxial connector 5 is transmitted through the microstrip taper balun 4 connected to the coaxial connector 5 to the parallel two-wire line 3 connected to the microstrip taper balun 4. From the coaxial transmission mode to the parallel two-wire transmission mode.

The microwave converted to the parallel two-wire transmission mode is supplied to the two spiral conductors 2 connected to the parallel two-wire line 3 in opposite phases, and the circumference of the spiral conductor is 1
It is radiated on the front and back of the spiral conductor 2 at the frequency that becomes the wavelength.

The microwave radiated to the cavity side is reflected by the cavity bottom surface 11, and a part of the reflected microwave passes through the space between the spiral conductors 2 and is re-radiated.
Another part of the reflected microwave is coupled to the spiral conductor 2 to excite and re-emit the current.

As an example, as shown in FIG. 2, when the cavity bottom surface 11 has a plurality of projections 15, the radiated microwave 13 on the cavity side is irregularly reflected by the cavity bottom surface having the projections 15, and The reflected microwave 14 propagates while tilting in a wide-angle direction which is a direction horizontal to the spiral conductor 2.

Therefore, a part of the microwave 13 reflected from the cavity bottom surface 11 passes between the spiral conductors 2 in a wide angle direction and is re-emitted, so that the beam width can be widened.

Embodiment 2 FIG. 3 is a configuration diagram of a spiral antenna according to Embodiment 2 of the present invention. In the figure, 1 to 8 are the same as those in the first embodiment of the first invention, and 16 is a cavity bottom surface having a convex curved surface.

The description of the spiral antenna is the same as that of the first embodiment, and the microwave can be reflected at a wide angle by the shape of the cavity bottom surface 16 having the convex curved surface, so that the beam width can be widened.

[0022]

The spiral antenna according to the first aspect of the present invention has a configuration in which a plurality of projections are provided on the bottom surface of the cavity portion, so that the effect of widening the beam width in the wide angle direction can be obtained.

The spiral antenna according to the second aspect of the invention has a configuration in which the bottom surface of the cavity portion has a curved surface protruding in the direction of the spiral conductor, so that the same effect as that of the first aspect is obtained. Since the shape is simple, an effect of facilitating the production can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a view showing a radiation mode of microwaves radiated to a cavity side according to the first embodiment of the present invention.

FIG. 3 is a configuration sectional view of a spiral antenna according to a second embodiment of the present invention.

FIG. 4 is a configuration sectional view of a conventional spiral antenna.

FIG. 5 is a diagram illustrating a radiation mode by a conventional spiral antenna.

FIG. 6 is a view showing a radiation mode of microwaves radiated toward the cavity side by the conventional antenna device.

[Explanation of symbols]

1 antenna radiation element, 2 spiral conductor, 3 parallel two-wire line, 4 microstop taper balun, 5 coaxial connector, 6 coaxial connector inner conductor, 7 coaxial connector outer conductor, 8 cavity, 9 structure, 11 cavity bottom,
A bottom surface of the cavity having 15 protrusions and 16 convex curved surfaces.

Claims (2)

[Claims] An antenna radiating element having two spiral conductors formed on a surface of a dielectric substrate; and a spiral conductor provided on one surface of the antenna radiating element for holding an end of the dielectric substrate. A structure having a cavity structure having an air gap in a portion thereof, and a mode conversion of a parallel two-wire line provided through the bottom of the cavity on the structure side into a coaxial line in order to supply power to the two spiral conductors. A spiral antenna comprising a microstrip taper balun and a coaxial connector provided at the end opposite to the antenna radiating element of the microstrip taper balun, wherein a plurality of protrusions are provided on the bottom surface of the cavity portion. A spiral antenna characterized by the following. 2. An antenna radiating element having two spiral conductors formed on the surface of a dielectric substrate, and the spiral conductor provided on one surface of the antenna radiating element and holding an end of the dielectric substrate. A structure having a cavity structure having an air gap in a portion thereof, and a mode conversion of a parallel two-wire line provided through the bottom of the cavity on the structure side into a coaxial line in order to supply power to the two spiral conductors. A spiral antenna composed of a microstrip taper balun and a coaxial connector provided at the end opposite to the antenna radiating element of the microstrip taper balun. A spiral antenna having a bottom surface having such a curved surface.