KR101092954B1 - A right-angle-coupled polarization transition of waveguide and method of designing the same - Google Patents

Abstract

The present invention relates to a vertically coupled polarization transducer of a waveguide, and has an arbitrary polarization direction, is coupled to the first waveguide to which the electromagnetic wave is incident, and is perpendicularly coupled to the first waveguide, and receives the electromagnetic wave incident on the first waveguide. A second waveguide for transmitting electromagnetic waves in a polarization direction different from the polarization direction of the first waveguide, and a coupling portion of the first waveguide and the second waveguide, the polarization direction of the electromagnetic wave incident on the first waveguide It characterized in that it comprises a groove (groove) for converting in the polarization direction of the two waveguides.

Waveguide, polarization, conversion, vertical, coupling

Description

Waveguide Vertically Coupled Polarization Converter and its Design Method {A RIGHT-ANGLE-COUPLED POLARIZATION TRANSITION OF WAVEGUIDE AND METHOD OF DESIGNING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide polarization converter, and more particularly, to a vertically coupled polarization transducer of a waveguide capable of converting a traveling direction and a polarization direction of an electromagnetic wave while minimizing use space by combining two waveguides having different polarization directions at right angles. .

When constructing a transceiver using waveguides in the microwave and millimeter wave bands, there is a need to convert the traveling direction or the polarization direction of electromagnetic waves propagating in the waveguide according to the arrangement of each component.

In order to convert the polarization direction of the electromagnetic wave propagating in the waveguide by 90 °, conventionally, a method of physically twisting the waveguide or a method of realizing the waveguide polarization by dividing the waveguide direction in several steps has been applied (FIG. 6A, FIG. 6A). b). However, when manufacturing the waveguide polarization transducer by this method, there is a problem that a lot of space is required for the conversion of the polarization direction.

In addition, in order to convert the traveling direction of the electromagnetic wave propagating in the waveguide by 90 °, the conventional method maintains the same polarization direction and converts the traveling direction of the electromagnetic wave by 90 ° by bending the waveguide in a round shape having a constant radius (see FIG. 6C). ), A method of allowing the waveguide to be converted in small steps, such as by combining the waveguides in a staircase form, has been commonly used. However, this method has a problem in that a large amount of space is required to change the direction of propagation of electromagnetic waves.

According to the prior art as described above, the waveguide bent at 90 ° for the conversion of the wave direction and the waveguide twisted at 90 ° for the polarization conversion in order to convert the wave direction by 90 ° while changing the traveling direction of the electromagnetic wave propagating in the waveguide by 90 °. Should be combined with each other. In this configuration, there was a difficulty in miniaturization due to the increase in the space occupied by the polarization converter.

Therefore, when the incidence port and the output port of the waveguide are perpendicular to each other and a characteristic different from the polarization direction of the incident port and the polarization direction of the output port is required by 90 °, a waveguide polarization direction converting apparatus that can be miniaturized is required. In fields such as fuse high frequency sensors for fuses and vehicle anti-collision radars, which require miniaturization, a device capable of converting a traveling direction and a polarization direction of an electromagnetic wave without requiring a large amount of space is required.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a vertically coupled polarization transducer of a waveguide capable of converting the traveling direction and the polarization direction of the electromagnetic wave while minimizing the use space.

Another object of the present invention is to provide a method of designing a vertically coupled polarization transducer of a waveguide for optimizing polarization conversion efficiency.

In order to achieve the above object, the vertically coupled polarization converter of the waveguide according to the present invention,

A first waveguide having an arbitrary polarization direction and into which electromagnetic waves are incident;

A second waveguide coupled to the first waveguide at a right angle and receiving an electromagnetic wave incident on the first waveguide and transmitting an electromagnetic wave in a polarization direction different from the polarization direction of the first waveguide;

And a groove provided in a coupling portion of the first waveguide and the second waveguide, and configured to convert a polarization direction of the electromagnetic wave incident on the first waveguide into a polarization direction of the second waveguide.

Here, the first waveguide and the second waveguide may be spherical.

In addition, the groove may be spherical.

In addition, the second waveguide is coupled to the first waveguide at a right angle by rotating 90 ° based on the state of the first waveguide.

In addition, the groove polarizes a part of the electromagnetic waves incident on the first waveguide through a spherical structural feature.

In addition, an electromagnetic wave in which the polarization direction is converted by the groove in the coupling part and an electromagnetic wave which are not, are combined to convert the polarization direction of the electromagnetic wave incident on the first waveguide into the polarization direction of the second waveguide.

In addition, a method of designing a vertically coupled polarization converter of a waveguide according to the present invention in order to achieve the above another object, the first waveguide, the second waveguide is vertically coupled to the first waveguide, the first waveguide and the A design method of a vertically coupled polarization converter of a waveguide having a groove provided in a coupling portion coupled to a second waveguide,

(a) determining the center frequency of the vertically coupled polarization converter of the waveguide;

(b) determining the magnitude of the wavelength of the center frequency and the magnitudes of the first waveguide and the second waveguide according to the determined center frequency; And

(c) determining a detailed design variable based on the size of the wavelength of the center frequency and the size of the waveguide so that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized. do.

Herein, the design variable in step (c) may include a distance between the longitudinal section of the first waveguide and the longitudinal section of the groove, the length of the groove, the depth of the groove and the width of the groove.

The design variable may further include a horizontal length of the second waveguide when the horizontal length of the second waveguide is changed.

In addition, in step (c), (c-1) determining a separation distance between the longitudinal cross section of the first waveguide and the longitudinal cross section of the groove such that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized. step; (c-2) determining the length of the groove such that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized; (c-3) determining the depth and width of the groove such that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized; (c-4) determining whether there is a change in the design variables determined in the above step; And (c-5) if there is no change in the determination, setting the values of the design variables determined in the above step to the final design variable values.

Here, in the step (c-1), the separation distance between the longitudinal cross section of the first waveguide and the longitudinal cross section of the groove is 0 to 0.2λ ₀ (where λ ₀ = c ₀ / f ₀ , c ₀ : light velocity, f ₀ : Center frequency).

In addition, the length of the groove in the step (c-2) is determined by the following mathematical relationship.

Length of groove = c-β + δ

Where c is the horizontal length of the second waveguide, β is 0 to 0.2λ ₀ , δ is 0 to 0.1λ ₀ , λ ₀ = c ₀ / f ₀ , c _{0 is the} speed of light, and f _{0 is the} center frequency.

In addition, the depth of the groove and the width of the groove in the step (c-3) are respectively determined within the range of a / 2 ± 10% (a: transverse length of the first waveguide).

Further, between step (c-1) and step (c-2), between step (c-2) and step (c-3), step (c-3) and step (c-4) The method may further include determining whether the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are the lowest values.

In addition, between the step (c-3) and the step (c-4),

(d-1) determining whether the horizontal length of the second waveguide is variable; (d-2) If it is determined in step (d-1) that the horizontal length of the second waveguide is variable, the method may further include determining the horizontal length of the second waveguide.

 In the step (d-2), the horizontal length of the second waveguide is determined within a range in which the cutoff frequency of the second waveguide is lower than the frequency band of the electromagnetic wave delivered to the second waveguide, and the horizontal length of the second waveguide The functional relationship between the cutoff frequencies of the second waveguide is determined by the following equation.

[Equation]

f _c = c ₀ / (2c)

Where f _c is the cutoff frequency of the second waveguide, c is the horizontal length of the second waveguide, and c _{0 is the} light velocity.

The method may further include determining whether the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are the minimum values between the step (d-2) and the step (c-4).

According to the above-described vertically coupled polarization converter of the waveguide, the size of the converting portion in which the polarization direction is converted can be reduced, and it is possible to reduce the size and weight of the device since it does not require much space even when converting the traveling direction of the electromagnetic wave. Therefore, the present invention can be usefully used for the ultra-high frequency sensor for a fuse or a vehicle collision avoidance radar, which is required to be miniaturized, and can be widely applied to medical devices such as military and civil radar systems.

In addition, according to the above-described method of designing a waveguide polarizer, the reflection coefficients reflected by the first waveguide and the second waveguide can be minimized to maximize the polarization conversion efficiency at the coupling portion.

Since the present invention can be variously modified and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, the same reference numerals are used for the same components.

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

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

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. Terms, such as those defined in the commonly used dictionaries, should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. .

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

1 is a block diagram of a vertically coupled polarization converter of a waveguide according to an embodiment of the present invention.

FIG. 1A is a diagram of a vertically coupled polarization transducer of a waveguide viewed from the cross section of the AA ′ axis in FIG. 1.

Referring to FIG. 1, a vertically coupled polarization converter of a waveguide according to the present invention includes a first waveguide 10, a second waveguide 20, and a groove 30. Specifically, as shown in FIG. 1A, the outside of the vertically coupled polarization converter of the waveguide is surrounded by a conductor wall, and the inside thereof is empty. The opening face 13 of the first waveguide and the opening face of the second waveguide are shown. Only 24 is open, and the entire surface where the first waveguide 10 and the groove are coupled is penetrated and penetrated, and the entire shave through which the first waveguide 10 and the second waveguide 20 are coupled is penetrated.

The first waveguide 10 has an arbitrary polarization direction (eg TE ₁₀ Mode), the electromagnetic wave is incident, and the second waveguide 20 is coupled to the first waveguide 10 at a right angle, and receives the electromagnetic wave incident on the first waveguide 10 to receive the polarization direction of the first waveguide ( It emits electromagnetic waves in a polarization direction different from 14). The groove 30 is installed at a coupling portion between the first waveguide 10 and the second waveguide 20, and the polarization direction 14 of the electromagnetic wave incident on the first waveguide 10 corresponds to the second waveguide. Is converted to the polarization direction of. Here, the groove 30 is called a groove because it has a shape like a groove when viewed from inside the polarization converter.

Here, the first waveguide 10 and the second waveguide 20 may be a waveguide of various forms, preferably a rectangular waveguide of a rectangular waveguide is used, the square corners do not form a right angle radius Waveguides processed into circles less than or equal to b / 2 may also be used.

Here, the groove 30 may be used in various forms, but preferably has a spherical shape. Such a groove 30 can be seen as one waveguide in the form of a hollow metal tube.

Here, the second waveguide 20 is rotated by 90 ° based on the state of the first waveguide 10 is coupled to the first waveguide 10 at a right angle. Here, the second waveguide 20 is rotated by 90 ° with respect to the state of the first waveguide 10, the second waveguide 20 is a long side of the cross-section of the second waveguide 20 (hereinafter referred to as the second waveguide). It means that the long side of the cross section of the first waveguide (hereinafter referred to as the transverse of the waveguide) (hereinafter referred to as the transverse of the first waveguide) includes a cross section that forms an angle of 90 degrees. By such a configuration, the second waveguide 20 transmits the electromagnetic wave received from the first waveguide 10 in a polarization direction that is 90 ° different from the polarization direction 14 of the first waveguide.

Looking at the configuration of the vertically coupled polarization converter of the waveguide of the present invention as described above, the electromagnetic wave is incident through the opening surface 13 of the first waveguide, the polarization direction of the electric field formed in the first waveguide 10 ( 14 is a vertical direction of the transverse 11 of the first waveguide (for example, the basic polarization direction of TE ₁₀ ), and is a left-right direction based on the front of FIG. 1.

For reference, the opening face 13 of the first waveguide and the opening face 24 of the second waveguide can both be used as an input port and an output port, but in order to clearly explain the principle of polarization conversion, The opening face 13 of the waveguide is described as an input port, and the opening face 24 of the second waveguide is described as an output port.

In addition, the second waveguide 20 is coupled to the first waveguide 10 at a right angle, and the polarization direction 25 of the electric field formed in the second waveguide 20 is perpendicular to the horizontal 21 of the second waveguide. As a direction, it is the front-back direction from the front of FIG. In addition, the second waveguide 20 receives electromagnetic waves incident on the first waveguide 10 and transmits the electromagnetic waves to the opening surface (output port) 24 of the second waveguide. Here, the polarization direction of the electromagnetic wave transmitted to the opening surface (output port) 24 of the second waveguide coincides with the polarization direction 25 of the electric field formed in the second waveguide 20.

As shown in FIG. 1, the polarization direction 14 of the opening surface (incident port) 13 of the first waveguide and the polarization direction 25 of the opening surface 24 of the second waveguide are different from each other ( 90 °), in order for the electromagnetic wave incident on the opening face 13 of the first waveguide to be transmitted while minimizing the loss on the opening face 24 of the second waveguide, the polarization direction of the electromagnetic wave is the polarization direction of the second waveguide. Should be converted to (25). If the polarization direction of the electromagnetic wave incident on the first waveguide 10 is not converted, the electromagnetic wave incident on the first waveguide 10 has a second waveguide (since the polarization direction is orthogonal to the polarization direction of the second waveguide 20). You will not be able to proceed to 20).

As described above, the groove 30 is provided in the coupling portion where the first waveguide 10 and the second waveguide 20 are coupled, and the polarization direction 14 of the electromagnetic wave incident on the first waveguide 10 is provided. Is converted into the polarization direction 25 of the second waveguide. That is, the groove 30 serves to transmit the electromagnetic wave incident on the first waveguide 10 to the second waveguide 20 while minimizing the loss. Herein, the coupling part includes the first waveguide 10 including a cross section from which the first waveguide 10 and the groove 30 are coupled to a cross section where the first waveguide 10 and the second waveguide 20 are coupled to each other. Speaks area of.

FIG. 2A is a cross-sectional view taken along line A-A 'of FIG. 1 and illustrates a shape of an electric field formed in a vertically coupled polarization converter of a waveguide at an arbitrary point in time. FIG. 2B is a reference diagram for explaining the principle of converting the polarization direction of the electromagnetic wave traveling from the waveguide to the groove, (A) is a view showing the shape of the electric field in the cross section of the waveguide without the groove, (b) It is a figure which shows the electric field shape of the cross section of the waveguide with which the groove | channel was couple | bonded. Here, arrows shown in FIGS. 2A and 2B indicate polarization directions of electromagnetic waves. In addition, indicated by the solid line of the arrow of Fig. 2a means the case of the electromagnetic wave incident on the first waveguide, and indicated by a dashed-dotted line means the case of the electromagnetic wave reflected from the groove.

3A is a computer graphic diagram illustrating a process of converting a polarization direction of an electromagnetic wave incident on a vertically coupled polarization converter of a waveguide according to the present invention, and FIG. 3B illustrates an electromagnetic wave incident from the opening surface 13 of the first waveguide 10. Is a computer graphic diagram showing how the polarization is transformed according to the phase angle.

1 to 3, a process of converting the polarization direction 14 of the electromagnetic wave incident on the first waveguide 10 into the polarization direction 25 of the second waveguide is described. Through the structural feature, the polarization direction of some of the electromagnetic waves incident on the first waveguide (about 1/2 of incident power) is converted. That is, the groove 30 converts a polarization direction of a portion (about 1/2) of the electromagnetic waves incident on the first waveguide 10 by 90 ° in a direction parallel to the width 32 of the groove. In addition, the groove 30 retards a portion (about 1/2) of the electromagnetic wave incident on the first waveguide 10. By adjusting the depth 31 of the groove to determine the degree of phase delay, polarization conversion efficiency may be optimized. Determining the depth 31 of the groove is described in detail with respect to FIG. 4. In this way, the electromagnetic wave in which the polarization direction is converted by the groove 30 and the electromagnetic wave that is not converted by the coupling part are synthesized, so that the polarization direction 14 of the electromagnetic wave incident on the first waveguide 10 is changed to the second waveguide. The polarization direction 25 is converted.

Here, the polarization conversion process will be described in more detail. Referring to the front of FIG. 1, the polarization direction of the electromagnetic wave incident on the opening surface 13 of the first waveguide is left and right and proceeds toward the coupling portion. Some of the electromagnetic waves entering the coupling portion travel toward the groove 30. (The amount of electromagnetic waves propagating toward the groove among the electromagnetic waves incident on the first waveguide 10 can be adjusted by adjusting the value of the width of the groove 32. A process of setting the width 32 of the groove will be described later with reference to FIG. As an example (see FIG. 1A), when the width 32 of the grooves is about one half of the width 11 of the first waveguide, the width 32 of the grooves is transverse 11 of the first waveguide. Occupies about 1/2 of the first waveguide, and about half of the electromagnetic waves propagated at a uniform density in the first waveguide 10 proceed to the groove.

And the electromagnetic wave which advances to a groove | channel is converted 90 degree | times in the polarization direction (rear direction) whose polarization direction is parallel to the width | variety 32 of the groove | channel. Specifically, the first waveguide 10 and the groove 30 are coupled to each other by coupling the spherical groove 30 (which can be seen as one waveguide) to the first waveguide 10 having a spherical shape. The cross-sectional shape of the waveguide is changed as shown in FIG. 2B (b). Due to this change in shape, the electromagnetic wave in which the polarization direction is left and right in a predetermined region represented by a dotted line in the first waveguide 10 cannot be blocked by the cutoff frequency of the groove, and as shown in FIGS. 2A and 2B (b). Likewise, the polarization direction of the electromagnetic wave is rotated by 90 ° with respect to the corner at which the first waveguide 10 and the groove 30 are coupled to each other, and proceeds to the groove 30.

The electromagnetic waves propagated to the grooves 30 are reflected from the front of the grooves and are directed back to the coupling portion, and are combined with the other waves (about 1/2 of the incident electromagnetic waves) that do not proceed to the grooves 30 at the coupling portion. do. The polarization direction (front and rear direction) of the electromagnetic waves returned from the groove 30 and the polarization direction (left and right directions) of the other electromagnetic waves differ by 90 °, and two linear polarizations having different polarization directions at the coupling portion are synthesized. A circular polarization is formed in which the vector circles. By this synthesis, the electric field of the electromagnetic waves in the coupling portion rotates in the direction corresponding to the polarization direction of the second waveguide. Electromagnetic waves in the coupling portion converted in the polarization direction of the second waveguide by rotation proceed to the second waveguide.

With regard to the above-described conversion process of the polarization direction, it can be seen from FIG. 3A that the polarization direction 14 of the opening surface of the first waveguide is converted by 90 ° to the polarization direction 25 of the opening surface of the second waveguide. It can be seen through 3b that the electromagnetic wave incident on the first waveguide 10 at the coupling portion is well transmitted to the second waveguide 20 without being reflected.

4 is a flowchart illustrating an execution process of a method of designing a vertically coupled polarization converter of a waveguide according to the present invention.

Referring to FIG. 4, a method of designing a vertically coupled polarization converter of a waveguide according to the present invention includes a first waveguide 10, a second waveguide 20 vertically coupled to the first waveguide 10, and As a design method of a vertically coupled polarization transducer of a waveguide having a groove 30 provided in a coupling portion where the first waveguide 10 and the second waveguide 20 are coupled, first, the center frequency of the vertically coupled polarization transducer of the waveguide. (Step S401). Here, the center frequency is not limited to the frequency of a predetermined region, but can be selected in all frequency regions.

When the center frequency is determined in step S401, the size of the wavelength of the center frequency and the size of the first waveguide 10 and the second waveguide 20 are determined according to the determined center frequency (step S402). Here, the size of the center frequency wavelength λ ₀ is obtained by the following Equation 1, and the size of the waveguide is determined as the size at which the electromagnetic wave having the determined center frequency can be transmitted. If a standard waveguide is used, select it as the standard product according to the frequency band used.

[Equation 1]

When the size of the center frequency wavelength and the size of the first waveguide 10 and the second waveguide 20 in the step S402 is determined, the first waveguide based on the size of the wavelength and the size of the waveguide of the determined center frequency The detailed design variable is determined such that the reflection coefficient S ₁₁ and the reflection coefficient S ₂₂ of the second waveguide are minimized (steps S403 to S413). Specifically, the reflection coefficient S ₁₁ of the first waveguide and the reflection coefficient S of the second waveguide are performed by performing a predetermined simulation program for the design of the polarization converter based on the size of the wavelength of the center frequency and the waveguide size. ₂₂ ) Determine the design details so that the minimum is ₂₂ ). Here, a commercial electromagnetic field (EM) simulation software program (for example, CST MICROWAVE STUDIO ^® ) may be used as a predetermined simulation software program.

Here, the design variable is a distance 34 between the longitudinal section of the first waveguide 10 and the longitudinal section of the groove 30, the length of the groove 33, the depth 31 of the groove, and the width 32 of the groove. It may include.

In addition, when the length of the second waveguide transverse (long side of the second waveguide cross-section) 21 is variable, the length of the second waveguide transverse 21 may be further included as a design variable (see FIG. 4A). Since the width of the waveguide is inversely related to the characteristic impedance of the waveguide, when the width of the second waveguide is varied, the impedance of the first waveguide and the second waveguide is adjusted by adjusting the width 21 of the second waveguide as a design variable. This is to match and improve the polarization conversion efficiency through impedance matching.

The setting of the design variable is based on the following process.

First, in the simulation software, the basic design is performed by applying the structure of FIG. 1, the order of FIG. 4 (in some cases, the order of FIGS. 4A and 4B), equations for obtaining design variables, and initial values of design variables. Each design variable is then set to a variable parameter. Here, the initial value of the design variable is a value determined based on the wavelength of the center frequency and the waveguide size determined in step S402. The formula for obtaining the design variable and the initial value of the design variable (standard waveguide standard) are as follows. By

[Equation 2]

Distance 34 between the longitudinal section of the first waveguide and the longitudinal section of the groove;

Length of groove (33) = c (21) -β + δ

Initial value of groove depth 31 = a (11) / 2

Initial value of groove width 32 = a (11) / 2

Where β: 0 to 0.2λ ₀ , δ: 0 to 0.1λ ₀ , c (21): horizontal length of the second waveguide (long side length of the second waveguide cross section), a (11): horizontal length of the first waveguide (Long side length of 1st waveguide cross section) is shown, respectively.

Based on the above-described basic design, the longitudinal cross section of the first waveguide 10 and the longitudinal cross section of the groove 30 so that the reflection coefficient S ₁₁ of the first waveguide and the reflection coefficient S ₂₂ of the second waveguide are minimized. The separation distance 34 is determined (step S403). Specifically, the separation distance (beta) 34 between the longitudinal section of the first waveguide 10 and the longitudinal section of the groove 30 is 0 to 0.2λ ₀ (where λ ₀ = c ₀ / f ₀ , c ₀ : Luminous flux, f ₀ : center frequency). That is, the separation distance (β) 34 between the end face of the first waveguide 10 and the end face of the groove 30 is simulated at least 0.01λ ₀ in the range of 0 to 0.2λ ₀ so that the first waveguide is simulated. The reflection coefficient (S ₁₁ ) and the reflection coefficient (S ₂₂ ) of the second waveguide are obtained, and the simulation results show that the reflection coefficient (S ₁₁ ) of the first waveguide and the reflection coefficient (S ₂₂ ) of the second waveguide are the lowest (that is, polarization). The separation distance β 34 between the longitudinal section of the first waveguide 10 and the longitudinal section of the groove 30 is determined as a value at which the conversion efficiency is optimized). In this case, it should be noted that the frequency bandwidth used for the waveguide must also be determined.

In some cases, the separation distance (β) 34 between the longitudinal cross section of the first waveguide 10 and the longitudinal cross section of the groove 30 is 0 to 0 based on the initial value set by setting a predetermined value as an initial value. performing a simulation with a minimum interval in the 0.2λ 0.01λ _{0 0} range, and performing simulation result reflection coefficient (S ₁₁₎ and the reflection coefficient (S ₂₂₎ a minimum (i.e., the polarization conversion efficiency of the second waveguides in the first waveguide is Distance (β) 34 between the longitudinal section of the first waveguide 10 and the longitudinal section of the groove 30 may be determined. In particular, when the simulation is performed by setting the initial value to 0.12λ _{0, it} is possible to reduce the time for determining the separation distance (β) 34 between the longitudinal section of the first waveguide 10 and the longitudinal section of the groove 30. There is an advantage.

Next, the length 33 of the groove is determined so that the reflection coefficient S _{11 of} the first waveguide and the reflection coefficient S ₂₂ of the second waveguide are minimized (step S405). Specifically, the length of the groove is determined by the following equation (3).

[Equation 3]

Length of groove (33) = c-β + δ

Where c is the horizontal length of the second waveguide, β (separation distance between the longitudinal section of the first waveguide and the longitudinal section of the groove): 0 to 0.2λ ₀ , δ: 0 to 0.1λ ₀ , λ ₀ = c ₀ / f ₀ , c ₀ : speed of light, f ₀ : center frequency. The range in which the length 33 of the groove can be determined from the above equation is c-0.2λ ₀ to c + 0.1λ ₀ .

That is, the length 33 of the groove is applied to the value β (distance 34 between the longitudinal cross section of the first waveguide and the longitudinal cross section of the groove) determined in the step S403 in the equation for obtaining the length 33 of the groove, and The reflection coefficient of the first waveguide (S ₁₁ ) and the reflection coefficient of the second waveguide (S ₂₂ ) by performing simulation at least 0.01λ ₀ within the range of 0 to 0.1λ ₀ (range where δ is determined) based on the value. ), And the simulation results show that the length 33 of the groove is set to a value at which the reflection coefficient S ₁₁ of the first waveguide and the reflection coefficient S ₂₂ of the second waveguide are the lowest (that is, the polarization conversion efficiency is maximized). Decide In the case of δ, similarly to β, the simulation can be executed based on the set initial value by setting a predetermined initial value. In particular, when the initial value of δ is set to 0, simulation can be performed to reduce the time for determining the length 33 of the groove.

Next, the depth 31 of the groove and the width 32 of the groove are determined so that the reflection coefficient S _{11 of} the first waveguide and the reflection coefficient S ₂₂ of the second waveguide are minimized (step S407). ). Specifically, the depth 31 of the groove and the width 32 of the groove are respectively determined within a / 2 ± 10% range. That is, the depth 31 of the grooves and the width 32 of the grooves are simulated at least 0.01λ ₀ intervals within a / 2 ± 10%, so that the reflection coefficients S ₁₁ and the second waveguides of the first waveguide are simulated. The reflection coefficient (S ₂₂ ) of the waveguide is obtained, and the simulation results indicate that the reflection coefficient (S ₁₁ ) of the first waveguide and the reflection coefficient (S ₂₂ ) of the second waveguide are the lowest (that is, the polarization conversion efficiency is maximized). The depth 31 of the groove and the width 32 of the groove are respectively determined. For reference, the depth 31 of the groove and the width 32 of the groove are variables having less influence on the characteristics of the polarization converter. In addition, the depth 31 of the grooves and the width 32 of the grooves may be similarly set to other parameters to set the initial values and perform the simulation based on the set initial values. In particular, when the depth 31 of the groove and the width 32 of the groove are set to an initial value of a / 2, the depth 31 of the groove and the width 32 of the groove are determined by performing a simulation. You can save time.

Next, it is determined whether there is a change in the design variables determined in the above step (step S412). Specifically, this means that the design variables determined in steps S403, S405, and S407 are applied to determine whether there is no change in the design variables when the steps S403 to S407 are repeated. In addition, this step is likely to minimize the reflection coefficient from the determined design variable value due to the involvement of other factors, so the same process is repeated to set the optimum value that minimizes the reflection coefficient, that is, maximizes the polarization conversion efficiency. to be.

Next, if there is no change in the determination of step S412, the simulation is terminated and the values of the design variables determined in the above step are set to the final design variable values (step S413). That is, if there is no change in the determination of step S412, the values of the design variables determined in S403, S405, S407 are set to the final design variable value.

If there is a change in the values of the design variables determined in the above steps S403, S405, S407 in step S412, the program proceeds back to step S403.

FIG. 4A illustrates a method of designing a vertically coupled polarization converter of a waveguide shown in FIG. 4, wherein the horizontal length of the second waveguide is changed, and the horizontal length of the second waveguide is further included as a design variable. It is a flow chart.

According to an exemplary embodiment of the present invention, there is provided a method between the step S407 and the step S412, as shown in FIG. 4A, determining whether the length 21 of the second waveguide is varied (step S409); If it is determined in step S409 that the horizontal length of the second waveguide is variable, determining the horizontal length of the second waveguide such that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized ( Step S410 may be further included.

Referring to Figure 4a in detail,

After step S407, it is determined whether the length 21 of the second waveguide is varied (step S409). Here, the case where the horizontal length of the second waveguide is variable means that when the arbitrary waveguide is used or when the waveguide slot is processed in the module (conductor block), the width and length of the waveguide can be changed.

If it is determined in the step S409 that the length 21 of the second waveguide is not variable, the process proceeds to step S412. In this case, the step S412 means determining whether there is no change in the design variables when the steps S403 to S409 are repeated by applying the design variables determined in the steps S403, S405, and S407. If there is no change in the design variables as a result of the determination in step S412, the simulation is terminated and the design variables determined in the above step are set as the final design variables (step S413). Here, the final design variables are the design variables determined in the above steps S403, S405 and S407.

If it is determined in step S409 that the length 21 of the second waveguide is determined to be variable, the width of the second waveguide is minimized so that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimum. The length is determined (step S410).

Here, the length 21 of the second waveguide is determined within a range in which the cutoff frequency of the second waveguide 20 is lower than the frequency band of the electromagnetic wave transmitted to the second waveguide 20. That is, the width 21 of the second waveguide is a frequency having a minimum value among the frequency bands in which the cutoff frequency of the second waveguide 20 is transmitted to the second waveguide 20 (the frequency used for the polarization converter according to the present invention). Determine within a range lower than the frequency of the band). Here, the functional relationship between the width 21 of the second waveguide and the cutoff frequency of the second waveguide 20 is represented by Equation 4.

[Equation 4]

f _c = c ₀ / (2c)

Where f _c is the cutoff frequency of the second waveguide, c is the width 21 of the second waveguide, and c _{0 is the} light velocity.

From the above equation, the range in which c, the length 21 of the second waveguide, can be determined is c _{f0 = fc} <c ≦ 2d. Here, c _{f0 = fc} : when the center frequency and the cutoff frequency of the second waveguide are the same, the horizontal length of the second waveguide and d: the vertical length of the second waveguide (vertical length of the standard waveguide) are respectively shown.

The process of determining the width 21 of the second waveguide based on the above-mentioned contents is summarized. The length 21 of the second waveguide is simulated at least 0.01λ ₀ within the above range. to obtain a reflection coefficient (S ₂₂₎ of the reflection coefficient of the wave guide (S ₁₁₎ and a second waveguide, a simulation execution results reflection coefficient of the first waveguide (S ₁₁₎ and the second is also the reflection coefficient of pagwan (S ₂₂₎ the The length 21 of the second waveguide is determined as the lowest value (that is, the polarization conversion efficiency is optimal).

When the length 21 of the second waveguide is determined in step S410, the flow proceeds to step S412. In this case, the step S412 means determining whether there is no change in the design variables when the steps S403 to S410 are repeated by applying the design variables determined in the steps S403, S405, S407, and S410 (step S412). If there is no change in the design variable as a result of the determination in step S412, the simulation is terminated and the design variable determined in the above step is set as the final design variable (step S413). Here, the final design variables are the design variables determined in the above steps S403, S405, S407, S410.

4B is a flowchart illustrating an execution process of a design method further comprising determining whether the reflection coefficient is the lowest value from the determined design variable value in the design method of the vertically coupled polarization converter of the waveguide shown in FIGS. 4 and 4A.

The design method of the present invention is a first waveguide between the step S403 and the step S405, as shown in Figure 4b, at a distance 34 between the longitudinal cross section of the groove and the longitudinal cross section of the first waveguide determined in the step S403. The method may further include determining whether the reflection coefficient S ₁₁ and the reflection coefficient S ₂₂ of the second waveguide are the lowest values (step S404). This is to confirm whether the value determined in step S403 is a value for maximizing polarization conversion efficiency.

In addition, the design method of the present invention between the step S405 and step S407, as shown in Figure 4b, the reflection coefficient (S ₁₁ ) of the first waveguide at the length 33 of the groove determined in the step S405 and The method may further include determining whether the reflection coefficient S ₂₂ of the second waveguide is the lowest value (step S406). This is to confirm whether the value determined in step S405 is a value for maximizing polarization conversion efficiency.

In addition, the design method of the present invention, between the step S407 and step S409, as shown in Figure 4b, the depth of the groove 31 and the width 32 of the groove determined in the step S407 of the first waveguide The method may further include determining whether the reflection coefficient S ₁₁ and the reflection coefficient S ₂₂ of the second waveguide are the lowest values (step S408). This is to confirm whether the value determined in step S407 is a value for maximizing polarization conversion efficiency.

In addition, the design method of the present invention, between the step S410 and the step S412, as shown in Figure 4b, the reflection coefficient of the first waveguide (S ₁₁ ) at the length 21 of the second waveguide determined in the step S410 ) And determining whether the reflection coefficient S ₂₂ of the second waveguide is the lowest value (step S411). This is to confirm whether the value determined in step S410 is a value for maximizing polarization conversion efficiency.

5 is a graph showing the characteristics of the S-parameters in the series-coupled polarization converter of the waveguide manufactured by the design method of the vertically-coupled polarization converter of the waveguide according to the present invention. 5, which the second waveguide 20 in the transmission coefficient S ₂₁ of the first waveguide 10. The first waveguide 10 Simulation of the reflection coefficient S ₁₁ is reflected in the first waveguide (10) This is the result obtained. The computational frequency was performed in the W-band, which is the millimeter wave band, and the center frequency was normalized to 0 GHz. As shown in FIG. 5, the reflection coefficient is -20 dB or less, the transmission coefficient is -0.2 dB or more, and the polarization direction conversion efficiency is good based on the center frequency.

As described above, according to the waveguide vertically coupled polarization converter according to the present invention, it is possible to reduce the size of the conversion unit for converting the polarization direction, and does not require much space in converting the traveling direction of the electromagnetic wave, thereby miniaturizing the device And it is possible to reduce the weight. Therefore, the present invention can be usefully used for the ultra-high frequency sensor for a fuse or a vehicle collision avoidance radar, which is required to be miniaturized, and can be widely applied to medical devices such as military and civil radar systems.

In addition, according to the design method of the vertically coupled polarization converter of the waveguide of the present invention, it is possible to maximize the polarization conversion efficiency at the coupling portion by minimizing the reflection coefficient reflected from the waveguide.

1 is a view showing the configuration of a vertically coupled polarization converter of the waveguide according to the present invention.

FIG. 1A is a diagram of a vertically coupled polarization transducer of a waveguide viewed from the cross section of AA ′ in FIG. 1.

FIG. 2A illustrates the shape of an electric field formed in the vertically coupled polarization converter of a waveguide at an arbitrary time point of FIG. 1A.

FIG. 2B is a reference diagram for explaining the principle of converting the polarization direction of the electromagnetic wave traveling from the waveguide to the groove, (A) is a view showing the shape of the electric field in the cross-section of the waveguide without the groove, (B) It is a figure which shows the shape of the electric field of the cross section of this combined waveguide.

3A is a diagram illustrating a polarization direction of an electromagnetic wave incident on a first waveguide in a vertically coupled polarization converter of a waveguide according to the present invention through computer graphics.

3B is a diagram illustrating a process of converting a polarization direction according to a phase change of an electromagnetic wave incident on a first waveguide in a vertically coupled polarization converter of a waveguide according to the present invention through computer graphics.

4 is a flowchart illustrating a design process of a vertically coupled polarization converter of a waveguide according to the present invention.

FIG. 4A illustrates a method of designing a vertically coupled polarization converter of a waveguide shown in FIG. 4 when the horizontal length of the second waveguide is varied, further including a horizontal length of the second waveguide as a design variable. It is a flow chart.

4B is a flowchart illustrating an execution process of a design method further comprising determining whether the reflection coefficient is the lowest value from the determined design variable value in the design method of the vertically coupled polarization converter of the waveguide shown in FIGS. 4 and 4A.

5 is a graph showing the characteristics of the S-parameters in the series-coupled polarization converter of the waveguide manufactured by the design method of the vertically-coupled polarization converter of the waveguide according to the present invention.

6A and 6B are views illustrating a conventional polarization converter for converting a polarization direction of an electromagnetic wave by 90 °, and FIG. 6C is a view illustrating a prior art for converting a traveling direction of electromagnetic waves by 90 °.

<Description of the symbols for the main parts of the drawings>

10: first waveguide 11: width of the first waveguide (long side of the first waveguide cross section)

12: length of the first waveguide (short side of the cross section of the first waveguide)

13: opening surface of the first waveguide, 14: polarization direction of the first waveguide

20: second waveguide 21: width of second waveguide (long side of second waveguide cross section)

22: length of second waveguide (short side of second waveguide cross section)

23: position indication of the junction of the first waveguide and the second waveguide

24: opening surface of the second waveguide 25: polarization direction of the second waveguide

30: groove 31: depth of groove 32: width of groove 33: length of groove
34: distance between the longitudinal section of the first waveguide and the longitudinal section of the groove

Claims (17)

delete delete delete delete delete delete A method of designing a vertically coupled polarization transducer of a waveguide having a first waveguide, a second waveguide vertically coupled to the first waveguide, and a groove provided in a coupling portion where the first waveguide and the second waveguide are coupled. , (a) determining the center frequency of the vertically coupled polarization converter of the waveguide; (b) determining the magnitude of the wavelength of the center frequency and the magnitudes of the first waveguide and the second waveguide according to the determined center frequency; And (c) determining a detailed design variable based on the size of the wavelength of the center frequency and the size of the waveguide so that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized. Method of designing a waveguide polarization converter to be used. The method of claim 7, wherein The design variable in step (c) includes a separation distance between the longitudinal cross section of the first waveguide and the longitudinal cross section of the groove, the length of the groove, the depth of the groove and the width of the groove. . The method of claim 8, The design variable may further include a transverse length of the second waveguide when the transverse length of the second waveguide is varied. 10. The method of claim 9, Step (c) is, (c-1) determining a separation distance between the longitudinal cross section of the first waveguide and the longitudinal cross section of the groove such that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized; (c-2) determining the length of the groove such that the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are minimized; (c-3) determining a depth of the groove and a width of the groove to minimize the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide; (c-4) determining whether there is a change in the design variables determined in the above step; And and (c-5) if there is no change in the determination, setting the values of the design variables determined in the above step to the final design variable values. The method of claim 10, In the step (c-1), the distance between the longitudinal cross section of the first waveguide and the longitudinal cross section of the groove is 0 to 0.2λ ₀ (where λ ₀ = c ₀ / f ₀ , c ₀ : optical speed, f ₀ : center frequency) A method for designing a vertically coupled polarization converter of a waveguide, characterized in that determined within the range.  The method of claim 10, And the length of the groove in the step (c-2) is determined by the following mathematical relationship. [Equation] Length of groove = c-β + δ Where c is the second waveguide width, β is 0 to 0.2λ ₀ , δ is 0 to 0.1 ₀ , λ ₀ = c ₀ / f ₀ , c _{0 is the} speed of light, and f _{0 is the} center frequency. The method of claim 10, The depth of the groove and the width of the groove in the step (c-3) are each determined within the range of a / 2 ± 10% (a: first waveguide transverse length), the design of the waveguide vertically coupled polarizer converter Way. The method of claim 10, Between step (c-1) and step (c-2), between step (c-2) and step (c-3), between step (c-3) and step (c-4) And determining whether the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are the lowest values, respectively. The method of claim 10, Between the step (c-3) and the step (c-4), (d-1) determining whether the horizontal length of the second waveguide is variable; (d-2) when it is determined in step (d-1) that the horizontal length of the second waveguide is varied, the second reflection coefficient of the first waveguide and the second waveguide are minimized. A method of designing a vertically coupled polarization converter of a waveguide, characterized by further comprising the step of determining the width of the waveguide. The method of claim 15,  In the step (d-2), the horizontal length of the second waveguide is determined in a range lower than the frequency band of the electromagnetic wave delivered to the second waveguide by the number of cutoff frequencies of the second waveguide, and the horizontal length of the second waveguide The functional relationship between the cutoff frequency of the second waveguide is a method of designing a vertically coupled polarization converter of the waveguide, characterized by the following equation. [Equation] f _c = c ₀ / (2c) Where f _c is the cutoff frequency of the second waveguide, c is the horizontal length of the second waveguide, and c _{0 is the} light velocity. The method of claim 15, Between step (d-2) and step (c-4) And determining whether the reflection coefficient of the first waveguide and the reflection coefficient of the second waveguide are the lowest values.

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