KR102483308B1 - Quadrature hybrid coupler, a feed network and a circularly polarized antenna - Google Patents

Abstract

An input port, an isolated port, first and second output ports, a first shunt transmission line having a first impedance between the input port and the isolation port, and between the input port and the first output port. A first series transmission line having a second impedance, a second series transmission line having the second impedance between the isolation port and the second output port and being parallel to the first shunt transmission line, and the first, A quadrature hybrid coupler including a second shunt transmission line having the first impedance between two output ports and parallel to the first series transmission line.

Description

Quadrature hybrid coupler, a feed network and a circularly polarized antenna

The present invention relates to a quadrature hybrid coupler, a feed network, and a circular polarization antenna, and more particularly, to a quadrature hybrid coupler, a feed network, and a circular polarization antenna having a small phase difference variation of an output port in a wide frequency range.

Coupling refers to a phenomenon in which alternating signal energy is transmitted electromagnetically between independent spaces or lines.

A coupler is a device that artificially adjusts the degree of coupling, and arbitrarily adjusts the length and spacing of the line so that desired power is transmitted to one side.

In general, in a coupled line coupler, the distance between lines must be very narrow in order to increase the coupling coefficient.

To solve this problem, a hybrid coupler is used. In particular, a 90-degree hybrid coupler is an equal distribution coupler having a coupling of 3dB and is often used in a transmission/reception system.

1 is a diagram showing a general quadrature hybrid coupler.

As shown in this, the hybrid coupler is a 4-terminal network, and the electrical lengths of the first and second series transmission lines 11 and 12 and the first and second shunt transmission lines 21 and 22 are respectively It consists of a length of λ/4 of the center frequency.

In addition, the first and second series transmission lines 11 and 12 and the first and second shunt transmission lines 21 and 22 form a vertically/left-right symmetrical shape.

Here, the magnitude of each output of the first and second series transmission lines 11 and 12 is the same, and a signal having a phase difference of 90° is generated.

That is, signals having the same size and 90° phase difference are output from Port 2 (Output of through arm) and Port 3 (Output of coupled arm).

Meanwhile, Port 4 (Isolation Port) is isolated and cannot output any signal.

In addition, when the electrical lengths of the first and second series transmission lines 11 and 12 and the first and second shunt transmission lines 21 and 22 are λ/4 of the center frequency, respectively, The first and second series transmission lines 11 and 12 have a characteristic impedance of 35 Ω, and the first and second shunt transmission lines 21 and 22 have a characteristic impedance of 50 Ω.

When the quadrature hybrid coupler deviates from the center frequency, the electrical length of the first and second series transmission lines 11 and 12 and the first and second shunt transmission lines 21 and 22 change, so that the radiation pattern This asymmetrical transformation results in an increase in the axial ratio. In order to realize a wide axial bandwidth, additional structures such as metasurfaces, parasitic patches, and cavities should be applied.

Recently, a quadrature hybrid coupler with less variation in the phase difference of an output port in a wide frequency range is being studied.

An object of the present invention is to provide a quadrature hybrid coupler, a power supply network, and a circularly polarized antenna with little phase difference variation of an output port in a wide frequency range.

Another object of the present invention is to provide a quadrature hybrid coupler, a power supply network, and a circularly polarized antenna capable of symmetrically generating radiation patterns with a small size and broadband characteristics.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned above can be understood by the following description and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations indicated in the claims.

A quadrature hybrid coupler according to the present invention includes an input port, an isolated port, first and second output ports, a first shunt transmission line having a first impedance between the input port and the isolation port, the input port and A first series transmission line having a second impedance between the first output port, a second series transmission line having the second impedance between the isolation port and the second output port, and being parallel to the first shunt transmission line and a second shunt transmission line having the first impedance and parallel to the first series transmission line between the first and second output ports.

The first shunt transmission line may include a first portion connected to the input port and a second portion formed at a predetermined angle with the first portion and connected to the isolation port.

The first portion may be parallel to the second series transmission line.

The first series transmission line may include a third portion connected to the input port and a fourth portion formed at a predetermined angle with the third portion and connected to the first output port.

The third portion may be parallel to the second shunt transmission line.

The first and second shunt transmission lines may have a thickness of 0.4 mm to 0.6 mm, and the first and second series transmission lines may have a thickness of 0.7 mm to 0.9 mm.

A separation distance between the first shunt transmission line and the second series transmission line may be the same as a separation distance between the second shunt transmission line and the first series transmission line.

A separation distance between the first shunt transmission line and the second series transmission line may be 0.4 mm to 0.6 mm.

A line of the second output port may be bent to match a phase difference with the first output port to 90°.

A power supply network according to the present invention includes a first quadrature hybrid coupler and a second quadrature hybrid coupler connected to the first quadrature hybrid coupler in a symmetrical structure rotated by 180 ° with respect to an input port, wherein the first, Each of the two quadrature hybrid couplers includes the input port, an isolated port, first and second output ports, a first shunt transmission line having a first impedance between the input port and the isolation port, the input port and the second output port. A first series transmission line having a second impedance between the first output port, a second series transmission line having the second impedance between the isolation port and the second output port, and being parallel to the first shunt transmission line and a second shunt transmission line having the first impedance between the first and second output ports and parallel to the first series transmission line.

A circularly polarized antenna according to the present invention includes a first feed network, first and second dipoles connected to the first feed network in a left-right symmetrical structure, a second feed network independent of the first feed network, and left-right symmetrical to the second feed network. It includes third and fourth dipoles connected in a structure, wherein the first and second dipoles have opposite directions of currents supplied from the first feed network, a difference in electric field phase is 180°, and the third and fourth dipoles In this case, the direction of the current supplied from the second feed network is opposite, the electric field phase difference is 180 °, and the phases of the power radiated from the first to fourth dipoles are clockwise at 0 ° and -90 °, respectively. °, -180°, -270° can have a phase difference of 360°.

The quadrature hybrid coupler, the feed network, and the circularly polarized antenna according to the present invention have the advantage of reducing the area when constructing a circuit.

In addition, the quadrature hybrid coupler, the feed network, and the circularly polarized antenna according to the present invention have an advantage of improving reflection coefficient characteristics.

In addition, the quadrature hybrid coupler, the feed network, and the circularly polarized antenna according to the present invention have an advantage in that the phase difference variation of the output port is small in a wide frequency range.

On the other hand, the effects of the present invention are not limited to the effects mentioned above, and various effects may be included within a range apparent to those skilled in the art from the contents to be described below.

1 is a diagram showing a general quadrature hybrid coupler.
2 is a diagram showing a quadrature hybrid coupler according to an example of the present invention.
FIG. 3 is a diagram showing characteristics of the quadrature hybrid coupler shown in FIG. 2 .
4 is a diagram illustrating a power supply network including a quadrature hybrid coupler according to the present invention.
5 is a diagram showing characteristics of the power supply network shown in FIG. 4;
6 is a diagram illustrating a circularly polarized antenna to which a feed network including a quadrature hybrid coupler shown in FIG. 4 is applied.
FIG. 7 is a diagram showing the current surface distribution of the circularly polarized antenna shown in FIG. 6;

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The term and/or includes a combination of a plurality of related recited items or any one of a plurality of related recited items.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Expressions in the singular number include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, it should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram showing a quadrature hybrid coupler according to the present invention, and FIG. 3 is a diagram showing characteristics of the quadrature hybrid coupler shown in FIG. 2 .

2 and 3, the quadrature hybrid coupler 100 includes an input port (Port 1), an isolation port (Port 4), first and second output ports (Port 2 and Port 3), and first and second shunts. Transmission lines 111 and 112 and first and second series transmission lines 121 and 122 may be included.

Here, FIG. 2 (a) shows the geometric structure of the quadrature hybrid coupler 100, and FIG. 2 (b) shows the design structure of the quadrature hybrid coupler 100.

First, the input port (Port 1) may be a port through which a signal is input to a feeder line.

The isolation port (Port 4) is an isolation port and may be a port that does not output a signal.

In addition, the first and second output ports Port 2 and Port 3 output signals having the same size and 90° phase difference.

The first shunt transmission line 111 connects between the input port (Port 1) and the isolation port (Port 4) and may have a first impedance.

Here, the first shunt transmission line 111 may include first and second parts 111a and 111b.

The first part 111a is connected to the input port (Port 1), and the second part 111b forms a predetermined angle with the first part (Port 1) and is connected to the isolation port (Port 4).

The second shunt transmission line 112 is connected between the first and second output ports Port 2 and Port 3 and may have the same first impedance as the first shunt transmission line 111 .

The thickness (Wf) of each of the first and second shunt transmission lines 111 and 112 may be 0.4 mm to 0.6 mm, and if it is less than 0.4 mm, design difficulties may arise, and if it is greater than 0.7 mm, the area of the coupler may be increased. there is.

The first series transmission line 121 may have a second impedance between the input port (Port 1) and the first output port (Port 2).

Here, the first series transmission line 121 may include third and fourth portions 121a and 121b.

The third part 121a is connected to the input port (Port 1), and the fourth part 121b forms a predetermined angle with the third part 121a and is connected to the first output port (Port 2).

The second series transmission line 122 is connected between the isolation port (Port 4) and the second output port (Port 3), and may have the same second impedance as the first series transmission line 121.

Here, the length (Lq) of the second series transmission line 122 may be 7.7 mm to 7.9 mm, and the length (Lq) may be changed according to the thickness (Wq) and power of the second series transmission line 122. and is not limited thereto.

The thickness (Wq) of the first and second series transmission lines 121 and 122 may be 0.7 mm to 0.9 mm, and when less than 0.7 mm or greater than 1.0 mm, the power of the first and second output ports (Port 2 and Port 3) A phase difference may occur.

Here, the first portion 111a of the first shunt transmission line 111 may be formed parallel to the second series transmission line 122, and the second shunt transmission line 112 is the first series transmission line ( 121) may be formed in parallel with the third part 121a.

The separation distance g between the first portion 111a of the first shunt transmission line 111 and the second series transmission line 122 is It may be the same as the separation distance g between the third parts 121a.

Here, the separation distance (g) may be 0.4 mm to 0.6 mm. At this time, the separation distance (g) can be maintained equal to the thickness (Wq) of each of the first and second shunt transmission lines (111, 112), and the power phase difference between the first and second output ports (Port 2 and Port 3). can be kept constant.

In addition, the line of the second output port (Port 3) may be bent to match the phase difference with the first output port (Port 2) to 90°.

Conversely, the length (Lo) of the bent portion of the second output port (Port 3) may be 0.9 mm to 1.1 mm, and may vary according to the length of the first output port (Port 2), but is not limited thereto. don't

FIG. 3 shows simulated characteristics of the quadrature hybrid coupler 100 shown in FIG. 2, the quadrature hybrid coupler shown in FIG. 1, and the T-junction power divider to which a 90° phase delay line is added using ANSYS HFSS.

3(a) is the reflection coefficient of each structure, and it was designed to achieve the best impedance matching at 6.0 GHz.

It can be seen that the T-junction power divider has the best reflection coefficient characteristics, and the reflection coefficient characteristics of the quadrature hybrid coupler 100 are better than those of the quadrature hybrid coupler shown in FIG. 1 .

3(b) is a difference in power between the first and second output ports (Port 2 and Port 3).

In the T-junction power divider, the power difference between the first and second output ports (Port 2 and Port 3) was small in a wide range, and the power difference characteristic of the quadrature hybrid coupler 100 is the quadrature shown in FIG. It can be seen that it is better than hybrid.

3(c) is a phase difference of power between the first and second output ports (Port 2 and Port 3).

In the quadrature hybrid coupler shown in FIG. 1, the phase difference of power between the first and second output ports (Port 2 and Port 3) was constant in a wide range, and the power phase difference characteristic of the quadrature hybrid coupler 100 was T-junction power divider you can see it's better.

4 is a diagram showing a power supply network including a quadrature hybrid coupler according to the present invention, and FIG. 5 is a diagram showing characteristics of the power supply network shown in FIG. 4 .

Referring to FIGS. 4 and 5 , the power supply network 200 may include first and second quadrature hybrid couplers 210 and 220 .

Here, the first and second quadrature hybrid couplers 210 and 220 are formed in the same structure as the quadrature hybrid coupler 100 shown in FIG. , 2 output ports (Port 2 and Port 3), first and second shunt transmission lines 111 and 112, and first and second series transmission lines 121 and 122.

The first and second quadrature hybrid couplers 210 and 220 may be connected in a symmetrical structure rotated by 180° with respect to the input port (Port 1).

That is, the above-described symmetric structure is a structure in which the first and second quadrature hybrid couplers 210 and 220 having a phase difference of 90 ° are rotated by 180 ° around the input port (Port 1) and combined, so that the first quadrature hybrid coupler 210 of the first output port (Port 2), the second output port (Port 3), the first output port (Port 2) and the second output port (Port 3) of the second quadrature hybrid coupler 220 The output phase may be 0°, -90°, 0°, or -90°, respectively.

Since the configuration of each of the first and second quadrature hybrid couplers 210 and 220 is the same as that of the quadrature hybrid coupler 100 shown in FIG. 2, a detailed description thereof will be omitted.

Here, FIG. 5 shows characteristics of the power supply network shown in FIG. 4 .

5(a) is an S-parameter, and it can be seen that impedance matching is best achieved near the center frequency of 6.0 GHz, and the power sizes of the first and second output ports (Port 2 and Port 3) are almost the same.

5(b) shows the power phases of the first and second output ports (Port 2 and Port 3), and it can be seen that the difference between the power phases is constant over a wide range.

6 is a diagram showing a circularly polarized antenna to which a feed network including a quadrature hybrid coupler shown in FIG. 4 is applied, and FIG. 7 is a diagram showing a current surface distribution of the circularly polarized antenna shown in FIG. 6 .

Referring to FIGS. 6 and 7 , the antenna 300 represents a circularly polarized antenna combining the feed network 200 shown in FIG. 4 and a dipole.

Here, the antenna 300 may use a bent dipole to reduce an area.

The output ports of the two feed networks 200 may output power of 0°, -90°, 0°, and -90° phases in a clockwise direction, respectively. However, to implement circular polarization, the phases of power must be 0°, -90°, -180°, -270°, and circular polarization uses bent dipoles arranged symmetrically about the X-axis to provide an additional phase difference of 180°. can be implemented by introducing

That is, in the structure of the antenna 300 shown in FIG. 6, dipole pairs 1 and 2 and 3 and 4 may be sequentially connected to each output port of the feed network.

The directions of the currents flowing in the two dipoles that are left-right symmetric about the center are opposite, and the difference in phase of the radiated electric field may be 180°.

As shown in FIG. 6(a), when dipole pairs 1, 2, 3, and 4, which have a left-right symmetrical structure based on the center of the dipole, are connected to the power supply network, the phases of power radiated from the four dipoles are 0° in the clockwise direction, respectively. , -90°, -180°, -270°.

6(b) and 6(c) are top and bottom views of the antenna viewed from above. Design parameters Wi and Wo are adjusted for impedance matching, and the length of Lq can be adjusted to adjust the axial ratio.

Design parameters according to the structure of the antenna 300 constituting FIG. 6 (a) may be given as follows, but are not limited thereto.

W is mm, Wd is 0.5 mm. Ld is 10.2 mm, Lb1 is 3.3 mm, Lb2 is 2.5 mm, and W1 is 0.8 mm. W2 is 0.5 mm, Lq is 9.2 mm, g is 0.5 mm, and Wo is 0.3 mm. Lo may be 2 mm, Wr may be 1 mm, Lr may be 2.2 mm, Pt may be 1.7 mm, and Pb may be 3 mm.

At this time, FIG. 7 shows the antenna surface current distribution over time at a center frequency of 6 GHz by applying the above-described design parameters.

Observing the surface current distribution at times t, 0, T/4, T/2, and 3T/4, it can be confirmed that the current rotates counterclockwise (RHCP).

When applied to an antenna, the quadrature hybrid coupler and feed network according to the present invention can make a phase difference close to 90° in a wide frequency band, so that circular polarization can be easily implemented.

Features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified with respect to other embodiments by a person having ordinary knowledge in the field to which the embodiments belong. Therefore, contents related to these combinations and variations should be construed as being included in the scope of the present invention.

In addition, although the above has been described with reference to the embodiments, these are only examples and do not limit the present invention, and those skilled in the art to which the present invention belongs can exemplify the above to the extent that does not deviate from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications that have not been made are possible. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention as defined in the appended claims.

Claims (11)

input port;
an isolated port;
first and second output ports;
a first shunt transmission line having a first impedance between the input port and the isolation port;
a first series transmission line having a second impedance between the input port and the first output port;
a second series transmission line having the second impedance between the isolation port and the second output port and being parallel to the first shunt transmission line; and
a second shunt transmission line having the first impedance between the first and second output ports and being parallel to the first series transmission line;
In the second output port, the line is bent to match the phase difference with the first output port to 90 °,
The length of the bent portion of the second output port is 0.9 mm to 1.1 mm
Quadrature Hybrid Coupler. According to claim 1,
The first shunt transmission line,
a first portion coupled to the input port; and
a second portion angled with the first portion and connected to the isolation port;
Quadrature Hybrid Coupler. According to claim 2,
The first part,
Parallel to the second series transmission line and each other,
Quadrature Hybrid Coupler. According to claim 1,
The first series transmission line,
a third portion coupled to the input port; and
A fourth part formed at an angle with the third part and connected to the first output port,
Quadrature Hybrid Coupler. According to claim 4,
The third part,
Parallel to the second shunt transmission line,
Quadrature live lead coupler. According to claim 1,
The thickness of the first and second shunt transmission lines is
0.4 mm to 0.6 mm,
The thickness of the first and second series transmission lines,
0.7 mm to 0.9 mm,
Quadrature Hybrid Coupler. According to claim 1,
The separation distance between the first shunt transmission line and the second series transmission line,
Same as the separation distance between the second shunt transmission line and the first series transmission line,
Quadrature Hybrid Coupler. According to claim 7,
The separation distance between the first shunt transmission line and the second series transmission line,
0.4 mm to 0.6 mm,
Quadrature Hybrid Coupler. delete a first quadrature hybrid coupler; and
A second quadrature hybrid coupler connected to the first quadrature hybrid coupler in a symmetrical structure rotated by 180 ° based on the input port,
Each of the first and second quadrature hybrid couplers,
the input port;
an isolated port;
first and second output ports;
a first shunt transmission line having a first impedance between the input port and the isolation port;
a first series transmission line having a second impedance between the input port and the first output port;
a second series transmission line having the second impedance between the isolation port and the second output port and being parallel to the first shunt transmission line; and
a second shunt transmission line having the first impedance between the first and second output ports and being parallel to the first series transmission line;
In the second output port, the line is bent to match the phase difference with the first output port to 90 °,
The length of the bent portion of the second output port is 0.9 mm to 1.1 mm
feed network. delete

Images