JP2003289206A - Coplanar transmission line and high-frequency antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coplanar transmission line with less insertion losses. <P>SOLUTION: The coplanar transmission line is provided with a transmission conductor 1 on a one plane of a substrate 11, having insulation and with a grounding conductor 3 placed at both sides of the transmission conductor 1 apart from each other, the transmission conductor 1 has a curved part 8, and a phase shifter for delaying phases of an electric field is provided with inner side edge of the transmission conductor 1 at the curved part 8. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coplanar transmission line and a high frequency antenna suitable for communication of microwaves or millimeter waves.

[0002]

2. Description of the Related Art A coplanar wave guide, in which a transmission conductor and a ground conductor are provided adjacent to each other on one surface of an insulating substrate, can transmit high frequencies with a simple structure. It is used as a communication antenna for waves or millimeter waves. here,
Microwaves refer to radio waves with a frequency of 1 GHz to 3 THz, and millimeter waves refer to radio waves with a frequency of 30 to 300 GHz. Millimeter waves form part of the microwave band.

When the coplanar transmission line has a curved portion, there is a problem that a potential difference occurs between the ground conductors 3 on both sides and an insertion loss occurs. Conventionally, in order to solve this problem, FIG.
As shown in FIG. 1, since the ground conductors 3 on both sides were connected by the two wires 19, there was a problem in productivity.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a coplanar transmission line and a high frequency antenna which overcomes the aforementioned drawbacks of the prior art.

[0005]

SUMMARY OF THE INVENTION The present invention provides a coplanar transmission line in which a transmission conductor is provided on one surface of an insulating substrate, and ground conductors are provided on both sides of the transmission conductor with a space therebetween. The transmission conductor has a curved portion, and at least one selected from the inner edge of the transmission conductor in the curved portion and the inner edge of the transmission conductor in the vicinity of the curved portion is provided with a phase shifter for delaying the phase of the electric field. A coplanar transmission line is provided.

Further, according to the present invention, in a coplanar transmission line in which a transmission conductor is provided on one surface of an insulating substrate and ground conductors are provided on both sides of the transmission conductor with a space therebetween, a plurality of the transmission conductors are provided. And a phase shifter for delaying the phase of the electric field is provided in at least one selected from the inner edges of the transmission conductors in these bends and the inner edges of the transmission conductors in the vicinity of these bends. A coplanar transmission line is provided.

The present invention also provides a high frequency antenna having the above coplanar transmission line.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. 1 is a perspective view of an embodiment of the coplanar transmission line of the present invention, FIG. 2 is a plan view of the coplanar transmission line shown in FIG.
FIG. 3 is an enlarged plan view of the vicinity of the curved portion of the coplanar transmission line shown in FIGS.

In FIGS. 1, 2, and 3, 1 is a transmission conductor and 3
Is a ground conductor, 4 is a convex portion, 5 is a concave portion, 6a is an inner slot, 6b is an outer slot, 7 is a phase shifter region including a plurality of phase shifters, 8 is a curved portion, 11 is an insulating substrate, and g is The distance between the transmission conductor 1 and the ground conductor 3, L is the length of the phase shifter region 7, W is the conductor width of the transmission conductor 1, P _p is the period of the unevenness, and P _m is the amplitude of the period of the unevenness.

As shown in FIG. 1, the transmission conductor 1 is provided on one surface of the substrate 11 and the ground conductor 3 is provided on both sides of the transmission conductor 1 with a space therebetween.
And are provided. The transmission conductor 1 is provided with a curved portion 8. The bending portion 8 has a function of changing the signal transmission direction by bending the transmission conductor 1. Although the bent portion 8 shown in FIG. 1 is a bent portion, the bent portion 8 is not limited to this and may be a curved portion or the like.

In the present invention, at least one selected from the inner edge of the transmission conductor 1 in the curved portion 8 and the inner edge of the transmission conductor 1 in the vicinity of the curved portion 8 is provided with a phase shifter for delaying the phase of the electric field. When the transmission conductor has a plurality of curved portions 8, at least one selected from the inner edge of the transmission conductor 1 in these curved portions 8 and the inner edge of the transmission conductor 1 in the vicinity of these curved portions 8 is selected. A phase shifter that delays the phase of the electric field is provided.

This phase shifter has, for example, a shape of the inner edge of the transmission conductor 1 when a line overlapping the inner edge of the transmission conductor 1 is hypothesized (hereinafter, this line is referred to as an imaginary line) and the length L is constant. Is constructed by making the length of the virtual line as long as possible. In this way, the transmission conductor 1
In addition to forming the phase shifter by forming the inner edge of the substrate into a predetermined shape, the phase shifter can be formed by providing the inner slot 6a with a dielectric material having a higher dielectric constant than the material of the substrate 11.

When the phase shifter is formed by a predetermined shape of the inner edge of the transmission conductor 1, a repeating shape that repeats periodically is preferable. Average width of transmission conductor 1 and transmission conductor 1
Of the transmission conductor 1
This is because it is easy to adjust the average width of.

1, 2 and 3 show an example in which the shape of the inner edge of the transmission conductor 1 is a repetitive shape of irregularities, in other words, an example in which at least one repetitive shape selected from a square and a rectangle is adopted. Here, the convex portion 4 is configured by providing a conductor (conductor layer) on the substrate 11, and the concave portion is formed by not providing the conductor on the substrate 11 and
The first material is exposed and exposed.

The shape of the inner edge of the transmission conductor 1 is not limited to the repeating shape of the periodic unevenness shown in FIGS. 1, 2, and 3. For example, the shape of the inner edge of the transmission conductor 1 is triangular (see FIG. 8), a substantially triangular shape, a trapezoidal shape, a substantially trapezoidal shape, a semicircular shape, a substantially semicircular shape (see FIG. 9), a semi-elliptical shape, a substantially semi-elliptical shape, and the like, and a cyclic repeating shape of a combination of these shapes. However,
There is no particular limitation. The width of the transmission conductor 1 is preferably 0.8 mm or more. If it is 0.8 mm or less, the insertion loss is less likely to decrease even if the transmission conductor 1 phase shifter is provided.

FIG. 4 is a plan view of the phase shifter region 7 having a shape different from those of FIGS. An example of the repeating shape of the concavo-convex forming the phase shifter in FIG. 4 is that the depth of the concave portion 5 is deeper than the height of the convex portion 4 and the width of the concave portion 5 is narrower than the width of the convex portion 4, whereby the phase shifter region is formed. 7 is an example in which the average width W ′ of the transmission conductor 1 of No. 7 has the same dimension as the width W of the transmission conductor 1 other than the phase shifter region.

In the phase shifter shown in FIG. 4, the reason for making the depth of the concave portion 5 deeper than the height of the convex portion 4 is that the convex portion 4 comes into contact with the ground conductor 3 by increasing the height of the convex portion 4. This is to prevent this. Here, the height of the convex portion 4 and the depth of the concave portion 5 are based on the width W of the transmission conductor 1. It is preferable that 0.5W ≦ W ′ ≦ 1.2W.
When it is within this range, the insertion loss is smaller than when it is outside this range.

In the present invention, the phase shifter is provided on at least one selected from the inner edge of the transmission conductor in the curved portion 8 and the inner edge of the transmission conductor in the vicinity of the curved portion 8. In order to reduce the insertion loss, it is preferable to provide a phase shifter on the inner edge of the transmission conductor in the curved portion 8, but the curved portion 8
Insertion loss can be reduced even if a phase shifter is provided on the inner edge of the transmission conductor, which is slightly away from the transmission conductor.

Further, from the viewpoint that the insertion loss can be remarkably reduced, as shown in FIGS. 1, 2, 3 and 4, it is preferable to provide a phase shifter on both inner edges of the curved portion 8. But,
Without being limited to this, as shown in FIGS. 5 and 6, even if a phase shifter is provided on one of the inner edges of one side of the curved portion 8, the insertion loss can be reduced.

As shown in FIGS. 1, 2, 3 and 4, it is preferable that the lengths of the phase shifters on both sides of the curved portion 8 are the same or substantially the same and symmetrical so that the insertion loss can be reduced. However, the present invention is not limited to this, and as shown in FIG. 7, the insertion loss can be reduced even if the phase shifters on both sides of the curved portion 8 have different lengths and are asymmetric.

The reason why the insertion loss can be reduced by providing the phase shifter on the inner edge of the curved portion will be described. When the coplanar transmission line has a curved portion, the length of the inner slot 6a is shorter than that of the outer slot 6b. Therefore, the phase of the electric field propagating in the inner slot 6a advances as compared with the phase of the electric field propagating in the outer slot 6b, and a potential difference occurs between the ground conductors 3 on both sides, and the bilateral symmetry of the coplanar transmission line mode is lost. Therefore, the insertion loss increases.

Therefore, in the present invention, at least one selected from the inner edge of the transmission conductor in the curved portion 8 and the inner edge of the transmission conductor in the vicinity of the curved portion 8 is provided with a phase shifter for delaying the phase of the electric field, and the inner slot 6a is provided. The phase of the electric field propagating in the same as or almost the same as the phase of the electric field propagating in the outer slot 6b is set to minimize the insertion loss.

Here, the inner slot 6a and the outer slot 6b will be described. The inner slot 6a is an elongated region where the conductor is not provided on the substrate 11 between the inner edge of the transmission conductor 1 and the ground conductor 3. The elongated slot 6b is an elongated area where no conductor is provided on the substrate 11 between the outer edge of the transmission conductor 1 and the ground conductor 3. The inner slot 6a and the outer slot 6b are typically the substrate 1
Although the material of No. 1 is exposed by being exposed, the present invention is not limited to this, and is not limited to this.
An insulating material may be provided on top of.

Although the transmission conductor 1 has one curved portion in FIGS. 1 and 2, the transmission conductor 1 is not limited to this and may have a plurality of curved portions. Each of the plurality of curved portions 8 may be of a different type such as a bent portion or a curved portion.

When the transmission conductor 1 has a plurality of curved portions, phase shifters for delaying the phase of the electric field are provided at the inner edges of the transmission conductor in all the curved portions and the inner edges of the transmission conductor in the vicinity of all the curved portions. Preferably, at least one selected from the inner edge of the transmission conductor in the plurality of curved portions and the inner edge of the transmission conductor in the vicinity of the plurality of curved portions is provided with a phase shifter for delaying the phase of the electric field. By itself, insertion loss can be reduced.

FIG. 10 is a plan view in which the coplanar transmission line of the present invention is connected to a slot antenna which is a planar antenna. That is, in FIG. 10, the slot antenna is provided on the insulating substrate. In the slot area 20 of the slot antenna, the material of the insulating substrate is exposed and exposed. The connecting line 21 extends perpendicularly to the longitudinal direction of the slot region 20.
The connection line 21 connects the ground conductor 3 around the slot region 20 and the transmission conductor 1.

In the example of FIG. 10, at the time of reception, the reception signal excited by the slot antenna is sent to the receiver side (arrow 24) via the coplanar transmission line of the present invention. At the time of transmission, the transmission signal from the transmitter side (arrow 24) is sent to the slot antenna via the coplanar transmission line of the present invention.

In the example of FIG. 10, the combination of the coplanar transmission line of the present invention and the slot antenna is mentioned, but the present invention is not limited to this, and the antenna of another type such as a microstrip antenna can be used in combination with the present invention. It may be combined with a plane transmission line. Here, the microstrip antenna is a rectangular or circular shape on a dielectric substrate provided with a ground conductor.
An antenna having a patch radiation conductor (strip) of an elliptical shape or the like and having directivity in the direction perpendicular to the surface of the dielectric substrate on which the patch radiation conductor is provided. Moreover, it is effective and preferable that the present invention is applied to the frequency range of 1.0 to 10.0 GHz.

[0029]

EXAMPLES Examples will be described below. However, the present invention is not limited to these examples, and the present invention is not limited thereto unless it impairs the gist of the present invention.
Various improvements and changes are also included in the present invention. A glass plate, which is a dielectric, was used as the substrate 11, and a coplanar transmission line as shown in FIGS. The ground conductor and the transmission conductor were formed by printing silver paste in a predetermined shape on this glass plate and baking it. The dimensions of the substrate 11 are as follows. Fig. 12 shows the length L at a frequency of 10.0 GHz.
And the insertion loss, and Table 1 shows various numerical values related to the characteristics shown in FIG. The vertical dimension of the substrate 11 is 50 mm, the horizontal dimension of the substrate 11 is 50 mm, the thickness of the substrate 11 is 3.5 mm, the relative dielectric constant of the substrate 11 is 7.0, and the dielectric loss tangent of the substrate 11 is 0.01.

[0030]

[Table 1]

[0031]

According to the present invention, at least one selected from the inner edge of the transmission conductor in the curved portion and the inner edge of the transmission conductor in the vicinity of the curved portion is provided with the phase shifter for delaying the phase of the electric field. The potential difference between the ground conductors on both sides of the conductor hardly occurs and insertion loss is small.

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of a coplanar transmission line of the present invention.

FIG. 2 is a plan view of the coplanar transmission line shown in FIG.

FIG. 3 is an enlarged plan view in the vicinity of a curved portion of the coplanar transmission line shown in FIGS.

FIG. 4 is a plan view of a phase shifter region having a different shape from FIGS.

FIG. 5 is a plan view in which a phase shifter is provided on an inner edge of one side of a curved portion 8.

FIG. 6 is a plan view, which is another example different from FIG. 5, in which a phase shifter is provided on the inner edge of one side of the bent portion 8;

FIG. 7 is a plan view of an example in which the lengths of the phase shifters on both sides of the bending portion 8 are different and asymmetric.

FIG. 8 is a plan view of a phase shifter region having a shape different from that of FIGS.

9 is a plan view of a phase shifter region having a shape different from those in FIGS. 1, 2, 3, 4, and 5. FIG.

FIG. 10 is a plan view in which the coplanar transmission line of the present invention is used for a slot antenna which is a planar antenna.

FIG. 11 is a perspective view of a conventional coplanar transmission line.

FIG. 12 is a characteristic diagram of length L and insertion loss in the example.

[Explanation of symbols]

1: Transmission conductor 3: Ground conductor 4: Convex portion 5: Recessed portion 6a: Inner slot 6b: Outer slot 7: Phase shifter region 8: Curved portion 11: Insulating substrate g: Transmission conductor 1 and ground conductor 3 Interval L: Length of phase shifter region W: Conductor width of transmission conductor 1 P _p : Period of irregularity P _m : Amplitude of period of irregularity

Claims (4)

[Claims] 1. A transmission conductor on one surface of an insulating substrate,
In a coplanar transmission line in which a ground conductor is provided on both sides of the transmission conductor at a distance, the transmission conductor has a curved portion, and the inner edge of the transmission conductor in the curved portion and the curved portion A coplanar transmission line, wherein at least one selected from the inner edges of transmission conductors in the vicinity is provided with a phase shifter for delaying the phase of an electric field. 2. A transmission conductor on one surface of an insulating substrate,
In a coplanar transmission line in which ground conductors are provided on both sides of the transmission conductor with a space therebetween, the transmission conductor has a plurality of curved portions, and inner edges of the transmission conductor in these curved portions and these A co-planar transmission line characterized in that a phase shifter for delaying the phase of the electric field is provided in at least one selected from the inner edges of the transmission conductor in the vicinity of the curved portion of the above. 3. The coplanar transmission line according to claim 1, wherein the width of the transmission conductor 1 is 0.8 mm or more. 4. A high-frequency antenna having the coplanar transmission line according to claim 1, 2 or 3.