JPS6282803A - Antenna feeder - Google Patents

Abstract

PURPOSE:To reduce the generation of an excitation phase error and to reduce the size of an antenna system by adopting a microstrip line (MSL) and providing the MSL with the function of an impedance converter arranged on the outside of the antenna system. CONSTITUTION:Four plate members to which respectively corresponding MSLs 12 are laid are arranged in four spaces separated by two cross type supporting members. The plate members are arranged so that the opposite side of a dielectric base of each plate member to the surface forming the MSL is opposed to a supporting member 11 for the MSL 12 and the surfaces forming the MSLs 12 of all the plate members are orientated in the clockwise or counterclockwise direction. The terminal part of each MSL is connected to an electrode 1 on a dielectric plate 5 of a spiral antenna through a metallic conductor 15. The input side of each MSL 12 is formed like a taper so that its wide is wider than that of the output side to convert and match impedance.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to an antenna feed line, particularly an antenna feed line suitable for a multi-element spiral antenna.

b. Prior Art The prior art will be explained using a multi-element spiral antenna included in a spiral antenna as an example.

A multi-element spiral antenna has many antenna electrodes (
The electrodes are often formed on a plane, a conical surface, or a pyramidal surface. Further, the electrode arrangement can be self-complementary.

FIG. 1O is a conceptual perspective view of a planar four-element self-complementary spiral antenna.

In FIG. 10, electrode 1 is formed by four spiral windings, unidirectional directivity is given by cavity 2, feed line 3 is connected to electrode 1 at feed point 4, and winding 1 is connected to a dielectric plate. It is supported by 5. Note that when the winding 1 itself has sufficient strength, the dielectric plate 5 may not be used.

FIG. 11 is a sectional view of a planar four-element self-complementary spiral antenna having an antenna feed line according to the prior art.

In this type of antenna, four transmission lines run in parallel in the feed section, and if mutual coupling occurs, it will have a negative impact on the performance of the antenna, so it is necessary to use lines that do not cause coupling. . Therefore, in the conventional configuration, the power supply
A coaxial cable was used as gA3.

The feeding point 4 is a connecting portion between the feeding wire and the winding, but it is inevitable that the shape of the winding will be distorted from the desired shape at this portion. Therefore, in order to prevent the disturbance from affecting the characteristics, this portion must be made sufficiently smaller than the shortest wavelength used, and the coaxial cable must also be selected with a diameter commensurate with this.

The characteristic impedance of the feeder coaxial cable must be equal to the winding input impedance. On the other hand, the winding impedance is as high as 100Ω or more, and as a result, the center conductor is thin.

Since the impedance of components used in the feeder circuit connected to the antenna element terminal 31 is approximately 50Ω, it is common to interpose an impedance conversion circuit between the terminal 31 and the feeder circuit.

Problems to be solved by the invention
Since it is high at around 0.00, the center conductor of the coaxial cable needs to be extremely thin. As a result, it becomes difficult to ensure mechanical strength, and thin coaxial cables have the problem of increased loss and reduced gain.Furthermore, coaxial cables are not easy to process, resulting in poor dimensional accuracy and excitation There was a problem (defect) in that phase errors were likely to occur.

These problems are not limited to the exemplified four-element spiral antenna, but are common to multi-element self-complementary antennas.

d. Means for Solving the Problems The present invention employs a microstrip line as the feed line, which can easily form a higher impedance than a coaxial cable when compared with the same cross-sectional area, and is preferably placed outside the antenna. The above problem was solved by providing the microstrip line with the function of an impedance converter.

e. Effect Since the structure is such that a plurality of microstrip lines are adjacent to each other with a ground conductor in between, coupling between the lines can be sufficiently suppressed to the extent that it does not become a problem.

From the perspective of mechanical strength, microstrip lines are
Compared to a coaxial line, it is possible to use a thick center 49 body when realizing the same impedance with the same cross-sectional area. Since a thick conductor can be used for the connection at the center, which is the structural weakness of multi-element self-complementary antennas, the strength is increased compared to conventional structures.

This allows use at very high frequencies.

By adjusting the shape of the microstrip line, it can function as an impedance converter. For example, by making the microstrip line tapered, impedance matching between the antenna electrode and the feeder circuit can be achieved, and an impedance conversion device within the feeder circuit can be omitted compared to conventional methods. Therefore, the size of the antenna system as a whole can be reduced and loss can be reduced.

Since the structure allows the winding support dielectric plate and the microstrip line support to be mechanically fixed by adhesive, the strength against forces perpendicular to the winding support dielectric plate (such as vibrations) is dramatically increased. increase.

f, Embodiment FIG. 1 is a front view of a spiral antenna near the feed point using a preferred embodiment of the antenna feed line according to the present invention, and FIG. 2 is an elevational sectional view of the antenna of FIG. 1 near the feed line. It is.

Two microstrip line support members 11 made of a dielectric or metal conductor are combined in a cross shape, and one microstrip line is attached to each of the four spaces partitioned by the support members 11. A plate member is provided. The plate member includes a micros 1-rip line 12, a dielectric substrate 13, and a ground conductor 14 covering the back surface of the dielectric substrate.

The plate member is arranged such that the surface of the dielectric substrate 13 opposite to the surface on which the microstrip line is formed faces the microstrip line support member 11, and
- The surfaces on which the lip lines are formed are arranged in such a way that the surfaces on which the lip lines are formed are oriented clockwise or counterclockwise in all plate members. Note that the above microstrip line support member 1
When the support member 1 is made of metal, the support member 11 can function as a ground conductor, so it is not necessary to cover the dielectric substrate with the support member 11.

The terminal end of each microstrip line 12 is connected to the electrode l on the dielectric plate 5 of the spiral antenna by a metal conductor 15.

An input/output terminal 31 is provided on the feeding circuit side of the plate, and one end of the microstrip line 12 is coupled thereto. In this embodiment, the terminal 31 is a coaxial connector.

The input side of the microstrip line 12 is tapered so as to be wider than the output side.

This transforms the impedance and provides impedance matching.

FIG. 3 is a front view of the vicinity of the feed point of a spiral antenna using an antenna feed line according to another preferred embodiment of the present invention, and FIG. 4 is an elevational sectional view of the antenna of FIG. 3.

This embodiment is an example in which the support member 11 is made to protrude further from the surface of the electrode supporting dielectric substrate 5. With this structure, the connection part between the power supply cotton 3 and the electrode 1 is bonded with the adhesive 2.
1 and mechanically bonded, it is advantageous because a large bonding area can be obtained. Further, as shown in the figure, it is also possible to provide a large area (land) at the tip of the microstrip line, and the connection conductor 15 can be easily fixed.

FIG. 5 is an elevational sectional view of a modification of the embodiment illustrated in FIGS. 3 and 4. FIG.

This modification is an example in which a cut structure 22 for sandwiching the electrode support dielectric plate 5 is further added to the support member 11.

This cut structure ensures the fixation of the micros 1-rib line support member 11 and the dielectric substrate 5, and allows use under severe environmental conditions.

FIG. 6 is a front view of the vicinity of the feed point of a spiral antenna using an antenna feed line, which is a modification of the embodiment shown in FIGS. 3 and 5, and FIG. 7 is an elevation cross-section of the antenna shown in FIG. 6. It is a diagram.

In this embodiment, the support member 11 is surrounded by four metal bodies 23. With this structure, the coupling between the feeder lines 3 can be completely cut off, and the winding support dielectric plate 5 can be supported by the metal conductor 23, resulting in a more mechanically robust structure.

Although FIG. 7 shows the means shown in FIG. 5 as the means for connecting the microstrip line and the winding, it is also possible to use the means shown in FIGS. 2 and 4. Although FIG. 6 shows an example in which the metal conductor 23 has a cylindrical shape, it is also possible to have one conical or pyramidal shape for each column.

Although a planar four-element spiral antenna is illustrated as an example, it is clear that the present invention can also be applied to a multi-element self-complementary antenna having four or more electrode elements and whose electrode shape is not spiral.

In addition to multi-element self-complementary antennas in which electrodes are constructed on a flat surface, multi-element self-complementary antennas in which electrodes are constructed on conical or pyramidal surfaces have also been devised. is also applicable.

FIG. 8 shows a front view of the vicinity of the feeding point of an example applied to a conical eight-element spiral antenna, and FIG. 9 shows an elevational sectional view of FIG. 8.

g0 Effects of the invention 1) Compared to conventional methods, sufficient strength can be obtained with smaller dimensions.

ii) As a method for forming microstrip lines, it is now possible to employ an etching method that provides extremely high dimensional accuracy, and it is possible to maintain the lengths of a large number of feeder lines within extremely small variations. When conventional coaxial cables are used, it is difficult to maintain dimensional accuracy due to deformation during the processing process because the coaxial cable itself has a flexible structure. In multi-element self-complementary antennas, if the excitation phase deviates from the desired value, negative effects such as distortion of the radiation pattern will occur, so it is necessary to make the feed line lengths the same. The invention makes it possible to provide a feeder line with extremely small excitation phase error.

111) Mutual coupling between feeder lines can be kept sufficiently small.

The mutual coupling suppression effect can be increased by using metal for the support member 11. Further, by covering the support member 11 with a metal conductor, a complete suppressing effect can be achieved, and mutual coupling between the feed lines can be sufficiently suppressed.

iv) It is possible to provide an antenna that provides practical performance up to very high frequencies.

(2) By using an impedance converter using a microstrip line, the impedance converter in the feeder circuit can be omitted and loss is reduced, making it possible to provide an antenna system with high gain.

[Brief explanation of drawings]

FIG. 1 is a front view of the vicinity of the feed point of a spiral antenna using a preferred embodiment of the antenna feed line according to the present invention, FIG. 2 is an elevational cross-sectional view of the antenna of FIG. 1 near the feed line, and FIG. is a front view of the vicinity of the feed point of a spiral antenna using an antenna feed line according to another preferred embodiment of the present invention;
4 is an elevational sectional view of the antenna of FIG. 3, FIG. 5 is an elevational sectional view of a modification of the embodiment shown in FIGS. 3 and 4, and FIG. 6 is an elevational sectional view of the antenna of FIG. Figure 5 is a front view of the vicinity of the feed point of a spiral antenna using an antenna feed line, which is a modification of the embodiment shown in Figure 5. Figure 7 is an elevational sectional view of the antenna in Figure 6, and Figure 8 is a conical antenna. FIG. 9 is a front view of the vicinity of the feeding point of an example applied to an 8-element spiral antenna, FIG. 9 is an elevational cross-sectional view of FIG. 8, and FIG. FIG. 11 is a sectional view of a planar four-element self-complementary spiral antenna having an antenna feed line according to the prior art. I... Electrode, 2... Cavity, 3
...Power supply line, 4...Power supply point, 5...
Dielectric substrate, II... Microstrip line support member, 12...
・Microstrip line, 13... Dielectric substrate, 14... Ground conductor, I5
... Metal conductor, 22 ... Notch structure, 2
3... Metal conductor, 31... Antenna element terminal. #! 1 Figure jl! 2 Figure jI 3 ≦ Figure 4 Figure 5 FiA Figure 8 Figure 9 Figure 10 Figure 11

Claims (19)

[Claims] (1) An antenna feed line for feeding power to an antenna in which a plurality of feed points are concentrated at almost one point, comprising a plurality of microstrip line support members that intersect with a curve passing through the feed points, and a microstrip line support member. The above-mentioned plate members are arranged on the microstrip line support member so that at most one plate member is disposed in the space divided by the space defined by a microstrip line connecting each of the above-mentioned feeding points and the feeding circuit output terminal, the plate member having a dielectric substrate as the substrate;
An antenna feed line characterized by having a ground conductor located on the back side. (2) The antenna feed line according to claim (1), wherein the antenna is a spiral antenna. (3) The antenna feed line according to claim (1), wherein the antenna is a self-complementary antenna. (4) The antenna feed line according to claim (1), wherein the antenna is a multi-element antenna having four or more antenna electrodes. (5) The antenna feed line according to claim (1), wherein the antenna is formed on a flat surface. (6) The antenna feed line according to claim (1), wherein the antenna is formed on a conical surface or a pyramidal surface. (7) The antenna feed line according to claim 1, wherein the curved line is a straight line. (8) The antenna feed line according to claim (5), wherein the curved line is a normal line to the antenna plane. (9) The antenna feed line according to claim (6), wherein the curve corresponds to an extension of a center line of a conical surface or a pyramidal surface. (10) The antenna feed line according to claim (1), wherein the plate member has a flat plate shape. (11) Claim (7) characterized in that the plate member is arranged axially symmetrically about the straight line.
Antenna feed line as described in section. (12) The antenna feed line according to claim (1), wherein an impedance conversion circuit is formed on the feed circuit side of the microstrip line. (13) The antenna feed line according to claim (1), wherein the impedance conversion circuit is formed by expanding a portion of the conductor of the microstrip line on the feed circuit side into a tapered shape. . (14) The antenna feed line according to claim (1), wherein the microstrip support member is made of metal and functions as a ground conductor for the microstrip line. (15) Claim (1) characterized in that the outside of the plate portion protrudes from the surface of the antenna electrode support member.
Antenna feed line as described in section. (16) Claim (1) characterized in that the outside of the plate part has a structure that fits with an antenna electrode support member.
Antenna feed line as described in section. (17) The antenna feed line according to claim (1), wherein the plate member has a connection electrode having a width larger than the electrode width at the tip of the microstrip line electrode. (18) Claim 1, characterized in that the plate member is mechanically coupled to the antenna electrode support member.
) Antenna feed line described in section. (19) The antenna feed line according to claim (1), wherein the microstrip line support member is a microstrip line support member including a metal conductor surrounding the microstrip line support member.