Reflection-Type Vector Modulator Based on Liquid Crystal

Abstract

The present invention may include a reflective vector modulator, a coupler having an input port, an output port, a first load port, and a second load port; a first DC block electrically coupled to the first load port to block a DC or low-frequency current transmitted from the first load port; a second DC block electrically coupled to the second load port to block a DC or low-frequency current transmitted from the second load port; a first variable reactive load electrically coupled to the first DC block; a second variable reactive load electrically coupled to the second DC block; a first power supply unit for applying an electrical signal to the first variable reactive load; and a second power supply unit for applying an electrical signal to the second variable reactive load.

Description

Technology Field

[0001] The present invention relates to a reflection-type vector modulator, and more specifically, to a reflection-type vector modulator capable of varying the amplitude and phase of a propagating signal by combining a hybrid coupler and a variable reactive load. Background Technology

[0002] Existing frequency bands have become saturated in various wireless communication fields, including satellite, military, and commercial applications. Consequently, there is increasing demand for high-frequency millimeter wave bands, which offer advantages such as wide bandwidth and low latency.

[0003] Millimeter-wave communication offers the advantage of providing services with wide bandwidth and low latency, but the communication range can be reduced due to the high directivity and loss of radio waves. To overcome this, beamforming technology is utilized as a core component in millimeter-wave communication, such as 5G / 6G commercial communication. Beamforming is a technology that adjusts the phase and amplitude of radio signals input to multiple antennas to concentrate and radiate the output radio signals in a specific direction.

[0004] In the hardware design for implementing beamforming technology, phase shifters and attenuators connected to each of the multiple antennas are key elements. The phase of the input signal is controlled by the phase shifter, and the amplitude is controlled by the attenuator. Alternatively, a vector modulator that combines the functions of a phase shifter and an attenuator can be used.

[0005] A reflection-type phase shifter is designed by combining a hybrid coupler and a variable reactive load. The hybrid coupler of the reflection-type vector modulator consists of four ports, two of which are used as input and output, and the remaining two ports are each connected to a variable reactive load. Adjusting the impedance of the reactive load changes the phase of the output signal.

[0006] Typically, variable reactive loads are designed using diodes. Since the capacitance of a diode changes according to the applied voltage, its impedance can be electrically varied when used as a reactive load. However, designing reactive loads using diodes requires additional lumped element chips, such as resistors, capacitors, and inductors, which makes them unsuitable for or difficult to apply to millimeter-wave band designs. Lumped element chips generally form a self-resonant frequency below 10 GHz, which presents a problem in that it is difficult to accurately predict impedance values ​​in the millimeter-wave band above 30 GHz. The problem to be solved

[0007] The object of the present invention is to provide a reflection-type vector modulator capable of varying the amplitude and phase of a radio wave signal.

[0008] However, the technical problem that this embodiment aims to solve is not limited to the technical problem described above, and other technical problems may exist. means of solving the problem

[0009] The present invention, according to one embodiment of the present invention, may include a reflective vector modulator comprising: a coupler having an input port, an output port, a first load port, and a second load port; a first DC block electrically coupled to the first load port to block a DC or low-frequency current transmitted from the first load port; a second DC block electrically coupled to the second load port to block a DC or low-frequency current transmitted from the second load port; a first variable reactive load electrically coupled to the first DC block; a second variable reactive load electrically coupled to the second DC block; a first power supply unit for applying an electrical signal to the first variable reactive load; and a second power supply unit for applying an electrical signal to the second variable reactive load.

[0010] According to one embodiment, the first variable reactive load and the second variable reactive load may each be a liquid crystal-based reactive load.

[0011] According to one embodiment, the first variable reactive load and the second variable reactive load are composed of the same liquid crystal material, and the same voltage can be applied so that the first variable reactive load and the second variable reactive load have the same impedance.

[0012] According to one embodiment, the first variable reactive load and the second variable reactive load are composed of the same liquid crystal material, and different voltages can be applied so that the first variable reactive load and the second variable reactive load have different impedances.

[0013] According to one embodiment, the coupler may be a Branch Line type hybrid coupler.

[0014] According to one embodiment, a branch line type hybrid coupler and each of a first variable reactive load and a second variable reactive load can be connected to a high-impedance transmission line.

[0015] According to one embodiment, the first DC block and the second DC block may be coupling transmission lines.

[0016] According to one embodiment, voltage can be applied to the first power supply and the second power supply through a bias pin. Effects of the invention

[0017] According to the present invention, a reflective vector modulator capable of varying the amplitude and phase of a radio wave signal can be provided. Brief explanation of the drawing

[0018] FIG. 1 is a block diagram showing a reflective vector modulator according to one embodiment of the present invention. FIG. 2 is a plan view of a reflective vector modulator using a branch line hybrid coupler and a liquid crystal-based variable reactive load according to one embodiment of the present invention. FIGS. 3a and 3b are graphs showing amplitude and phase changes in the millimeter wave frequency band for a reflective vector modulator according to one embodiment of the present invention when the permittivity of the liquid crystals (218a, 218b) of two reactive loads (215a, 215b) is the same value. FIGS. 4a and 4b are graphs showing amplitude and phase changes in the millimeter wave band achieved by voltage control of the liquid crystal permittivity for the purpose of attenuator function for a reflective vector modulator according to one embodiment of the present invention. Specific details for implementing the invention

[0019] Embodiments of the present invention are described in detail below with reference to the attached drawings so that those skilled in the art can easily implement the invention. Since the present invention is susceptible to various modifications and may have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.

[0020] To clearly explain the present invention, parts unrelated to the description have been omitted from the drawings, and similar parts throughout the specification have been given similar reference numerals. Furthermore, while describing with reference to the drawings, even components indicated by the same name may have different drawing numbers depending on the drawing, and drawing numbers are provided merely for the convenience of explanation; the concept, feature, function, or effect of each component is not to be interpreted restrictively by the corresponding drawing number.

[0021] Similar reference numerals are used for similar components when describing each drawing. Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely 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 named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0022] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains.

[0023] Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0024] Throughout the specification, when a part is described as being "connected" to another part, this includes not only cases where they are "directly connected" but also cases where they are "electrically connected" with other elements interposed between them. Furthermore, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components; it should be understood that this does not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0025] In this specification, the term "unit" includes a unit realized by hardware or software, or a unit realized using both; a single unit may be realized using two or more pieces of hardware, or two or more units may be realized by a single piece of hardware.

[0026] Hereinafter, a reflective vector modulator according to the present invention will be described in detail with reference to the attached drawings.

[0027] FIG. 1 is a block diagram showing a reflective vector modulator according to one embodiment of the present invention.

[0028] Referring to FIG. 1, a reflective vector modulator (100) according to one embodiment of the present invention includes an input port (111), an output port (112), a hybrid coupler (113) having two load ports, a DC block (114a, 114b), a liquid crystal-based reactive load (115a, 115b), and a power supply (116a, 116b).

[0029] In the embodiment of FIG. 1, the hybrid coupler (113) is shown to include an input port (111), an output port (112), and two load ports (P1, P2), but the load ports of the hybrid coupler (113) are not limited to two, and may have two or more load ports depending on various design specifications and purposes.

[0030] The hybrid coupler (113) can be configured as a branch line type hybrid coupler. The ideal scattering parameter of the branch line type hybrid coupler (113) is given as Equation 1 below. A signal input to one of the four ports is divided into two ports with a 90° phase difference and is not transmitted to the remaining one port.

[0031] [Mathematical Formula 1]

[0032]

[0033] Typically, the two reactive loads (115) can be designed in various forms on a high-frequency substrate, such as microstriplines, striplines, waveguides, and substrate integrated waveguides (SIW).

[0034] The DC block (114a, 114b) can be designed so that direct current or low-frequency electrical signals are blocked without a metal line being connected, provided there is a sufficient distance. For example, it can be designed so that only radio waves pass through by using electrically disconnected coupling transmission lines (214a, 214b). Here, the low frequency range may be in the range of several Hz to several hundred Hz, and may be in the range of several Hz to several kHz depending on the design range.

[0035] In the present invention, a liquid crystal with variable electrical dielectric properties is used to control the impedance of reactive loads (115a, 115b). Accordingly, an external power source (116a, 116b) that generates a potential difference can be supplied to each liquid crystal-based reactive load (115a, 115b). To independently control the potential difference in each reactive load (115a, 115b), a DC block (114a, 114b), such as a chip, component, or structure, which serves to block direct current or low-frequency current between the hybrid coupler (113) and the reactive load (115a, 115b), may be added.

[0036] When two reactive loads (115a, 115b) have the same structure and use the same liquid crystal material, the impedances of the two loads can be matched by applying an external power source (116a, 116b) of the same voltage. In this example, the impedances of the two loads can be controlled to the same value by adjusting the voltage of the external power source (116a, 116b).

[0037] That is, a reflective vector modulator (100) according to one embodiment of the present invention can operate as a phase shifter that modulates in a range where the phase is greater than the amplitude of the output signal. In the ideal case where the reflection coefficient of two loads is given as Γ and the impedance is purely imaginary, the reflective vector modulator (100) of the present invention operates as a phase shifter and has a scattering parameter as shown in Equation 2.

[0038] [Mathematical Formula 2]

[0039] ,

[0041] Two loads with the same reflection coefficient value When having , the maximum value of the reflection coefficient achievable by voltage control , minimum value It can be set as follows. In this case, the phase shifter of the present invention exhibits a maximum phase shift amount as shown in Equation 3. In Equation 3 represents characteristic impedance.

[0043] [Mathematical Formula 3]

[0044]

[0046] According to another embodiment of the present invention, the impedances of two reactive loads (115a, 115b) can be changed to values ​​that are not the same. When external power sources (116a, 116b) of different voltages are applied, the impedances of the two loads may be different. In this case, the reflective vector modulator (100) of the present invention can operate as a vector modulator that controls both amplitude and phase.

[0047] FIG. 2 is a plan view of a reflective vector modulator using a branch line hybrid coupler and a liquid crystal-based variable reactive load according to one embodiment of the present invention.

[0048] Referring to FIG. 2, a reflective vector modulator (200) according to one embodiment of the present invention may include a hybrid coupler (113) using a branch line coupler (213), coupling transmission lines (214a, 214b), reactive loads (215a, 215b), bias pins (216a, 216b), liquid crystal injectors (217a, 217b), liquid crystals (218a, 218b), and high-impedance transmission lines (219a, 219b).

[0049] The two ports of the branch line coupler (213) are used as input (211) and output (212) of the radio signal, and depending on the symmetry, the roles of input and output can be switched.

[0050] The operating principle of the present invention is to be explained as follows.

[0051] An external power source (not shown) may be supplied to reactive load A (215a) and reactive load B (215b) through independent bias pins (216a, 216b). Depending on the voltage applied to the two reactive loads (215a, 215b), the dielectric properties of the liquid crystal (218a, 218b) located below or above the reactive loads (215a, 215b) may change. The change in dielectric properties of the liquid crystal (218a, 218b) may cause a change in the impedance of the two reactive loads (215a, 215b). The change in impedance of the two reactive loads (215a, 215b) may lead to amplitude and phase shifts in the propagation signal of the output (212) of the branch line coupler (213) connected thereto.

[0052] The coupling transmission lines (214a, 214b) can be used as DC blocks. Direct current or low-frequency electrical signals can be blocked if there is no metal line connected and a sufficient distance is maintained. Here, the low frequency range may be in the range of several Hz to several hundred Hz, and may be in the range of several Hz to several kHz depending on the design range.

[0053] High-impedance transmission lines (219a, 219b) may be used to connect the branch line coupler (213) and the reactive load (215a, 215b). However, if propagation or reflection between the branch line coupler (213) and the reactive load (215a, 215b) occurs as intended, the high-impedance transmission lines (219a, 219b) may function in a combined form with the coupling transmission lines (214a, 214b) or may be absent. The present design shows an embodiment of a reflective vector modulator designed for the purpose of the invention using high-impedance transmission lines (219a, 219b).

[0054] The impedance of the variable reactive load (215a, 215b) can change depending on the change in dielectric properties of the liquid crystal material injected below or above. An external power source (116) can be supplied to the conductive reactive load (215a, 215b) through the DC bias pins (216a, 216b). The DC bias pins (216a, 216b) may exist in various other forms to apply voltage to the reactive load (215a, 215b).

[0055] Liquid crystal material injection can be performed through liquid crystal injection ports (217a, 217b). Two or more liquid crystal injection ports (217a, 217b) can be made so that liquid crystal injection and air discharge can occur simultaneously, but the number of liquid crystal injection ports (217a, 217b) is not limited to this.

[0056] The liquid crystals (218a, 218b) used for the impedance change of the two reactive loads (215a, 215b) can be made of the same material. Liquid crystal A (218a) of reactive load 1 (215a) and liquid crystal B (218b) of reactive load 2 (215b) can have independent voltages applied to them. Although they are shown as two separate liquid crystals in FIG. 2, they may be a single liquid crystal filled through the liquid crystal injection ports (217a, 217b). The region where the electric field influence of the reactive load (215a) is greater can be defined as the region of liquid crystal A (218a), and the region where the electric field influence of the reactive load (215b) is greater can be defined as the region of liquid crystal B (218b).

[0057] A reflective vector modulator according to one embodiment of the present invention is a vector modulator capable of controlling both the amplitude and phase of a radio signal output, but includes operation as a phase shifter with almost no amplitude modulation and maximizing phase change, and operation as an attenuator with almost no phase modulation and maximizing amplitude change.

[0058] In the present invention, the liquid crystal used may preferably have a variable dielectric constant range of 2.5 to 3.5. When using a liquid crystal with such a dielectric constant range, there is typically a dielectric constant change of 50% or more when a voltage of approximately 3V is applied in the structure proposed in the present invention. Typically, a dielectric constant change of 90% or more can be observed when a voltage of approximately 10V is applied. However, the voltage required for the change in liquid crystal dielectric constant is not limited to the above examples and can be selected in various ways depending on the specific form and type of liquid crystal.

[0059] FIGS. 3a and 3b are graphs showing amplitude and phase changes in the millimeter wave frequency band for a reflective vector modulator according to one embodiment of the present invention when the permittivity of the liquid crystals (218a, 218b) of two reactive loads (215a, 215b) is the same value.

[0060] The same permittivity change in FIG. 3a and FIG. 3b can be achieved by adjusting the external power of the two reactive loads (215a, 215b) to the same voltage. The effective permittivity of liquid crystal A (218a) determined by the applied voltage , the effective permittivity of liquid crystal B (218b) If we say, And, This represents the amplitude and phase shift under conditions varying from 2.5 to 3.5.

[0061] If the liquid crystals (218a, 218b) of the two reactive loads (215a, 215b) have the same permittivity and the same structure, the impedances of the two loads are also the same. In this case, the reflective vector modulator of the present invention can ideally operate as a phase shifter in which only the phase is controlled and there is no amplitude modulation. As shown in FIG. 3a, it can be seen that the amplitude modulation is small in the operating frequency band of 35 to 37 GHz. In addition, as shown in FIG. 3b, it can be seen that the phase changes by more than 217° at 36 GHz.

[0062] FIGS. 4a and 4b are graphs showing amplitude and phase changes in the millimeter wave band achieved by voltage control of the liquid crystal permittivity for the purpose of attenuator function for a reflective vector modulator according to one embodiment of the present invention.

[0063] In FIG. 4a and 4b, different dielectric constant changes of the liquid crystals (218a, 218b) can be achieved by adjusting the external power supply (116) of the two reactive loads (215a, 215b) to different voltages. The effective dielectric constant of liquid crystal A (218a) determined by the applied voltage , the effective permittivity of liquid crystal B (218b) If so, for each case of the graph and All values ​​were displayed in the legend.

[0064] When the dielectric constant of the liquid crystals (218a, 218b) of the two reactive loads (215a, 215b) is appropriately controlled, it can operate as an attenuator capable of controlling only amplitude changes with almost no phase modulation. In FIG. 4a, it can be seen that the amplitude varies by more than 12dB at 36GHz. In addition, in FIG. 4b, it can be seen that the phase modulation is small in the operating frequency band of 35~37GHz.

[0065] The embodiments of the present invention described above may also be implemented in the form of a recording medium comprising computer-executable instructions, such as program modules executed by a computer. A computer-readable recording medium may include a computer storage medium, and the computer storage medium includes all volatile and non-volatile, removable and non-removable media implemented by any method or technique for storing information such as computer-readable instructions, data structures, program modules, or other data.

[0066] Although the apparatus and method of the present invention have been described in relation to specific embodiments, some or all of their components or operations may be implemented using a computer system having a general-purpose hardware architecture.

[0067] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0068] The scope of the present invention is defined by the claims set forth below rather than by the detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0069] 100, 200: Reflective vector modulator 111, 211: Input ports 112, 212: Output ports 113, 213: Hybrid coupler 114a, 114b: DC block 115a, 115b, 215a, 215b: Reactive load 116a, 116b: Power supply 214a, 214b: Coupling transmission line 216a, 216b: Bias pins 217a, 217b: Liquid crystal injection port 218a, 218b: Liquid crystal 219a, 219b: High-impedance transmission line

Claims

Claim 1 A coupler having an input port, an output port, a first load port, and a second load port; a first DC block electrically coupled to the first load port to block a DC or low-frequency current transmitted from the first load port; a second DC block electrically coupled to the second load port to block a DC or low-frequency current transmitted from the second load port; a first variable reactive load electrically coupled to the first DC block; a second variable reactive load electrically coupled to the second DC block; and a first power supply unit for applying an electrical signal to the first variable reactive load. A reflective vector modulator comprising a second power supply unit that applies an electrical signal to the second variable reactive load, wherein the first variable reactive load and the second variable reactive load are each liquid crystal-based reactive loads, and the first DC block and the second DC block are formed by physically separated coupling transmission lines, and wherein the first power supply unit and the second power supply unit independently apply voltages of different magnitudes to the first variable reactive load and the second variable reactive load, thereby controlling the first variable reactive load and the second variable reactive load to have different impedances, thereby simultaneously performing phase shifting and amplitude attenuation of the output radio signal. Claim 2 delete Claim 3 A reflective vector modulator according to claim 1, wherein the first variable reactive load and the second variable reactive load are composed of the same liquid crystal material, and the same voltage is applied so that the first variable reactive load and the second variable reactive load have the same impedance. Claim 4 delete Claim 5 In claim 1, the coupler is a reflective vector modulator that is a Branch Line type hybrid coupler. Claim 6 In claim 5, a reflective vector modulator in which the branch line type hybrid coupler, the first variable reactive load, and the second variable reactive load are each connected to a high-impedance transmission line. Claim 7 delete Claim 8 In claim 1, the first power supply and the second power supply are a reflective vector modulator to which voltage is applied through a bias pin.

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