Array Antenna and RF Network Apparatus for Millimeter-Wave Band with Distributed Diode Network

Abstract

The present specification relates to a distributed diode network array antenna configured with a stacked structure. A distributed diode network array antenna according to an embodiment of the present specification comprises: an antenna layer; a DC network layer which is a diode control network; and an RF network layer in which distribution and phase shifting of an RF (radio frequency) signal are performed. The RF network layer comprises at least one phase shifter that changes the phase of a signal. Each of the phase shifters comprises: a power divider that evenly distributes an input RF signal; a first phase shifter connected in front of the power divider that changes the phase of the input RF signal before the input RF signal is distributed; and two second phase shifters connected behind the power divider that each change the phase of the distributed RF signal.

Description

Technology Field

[0001] This specification describes a technology for a millimeter-wave band array antenna used in a wireless communication system, and in particular, a technology for improving signal transmission and reception performance through a distributed diode network. Background Technology

[0002] The millimeter wave band is attracting attention in next-generation communication systems, including 5G, 6G, and beyond, as it enables ultra-high-speed data transmission. Array antennas are a technology that can significantly improve communication performance by arranging multiple antenna elements to concentrate radio waves in a specific direction, and they are used in various fields such as wireless communication, radar systems, and satellite communication. Array antennas can control the direction of signals using beamforming, thereby providing high gain and directionality.

[0003] Array antenna technology is particularly important in the millimeter-wave band because it requires high gain due to the significant signal loss in the atmosphere. However, the millimeter-wave band presents challenges such as high signal transmission loss and complex antenna design resulting from differences in propagation characteristics depending on frequency. Furthermore, array antenna systems require precise control of phase changes through beam steering; consequently, increasingly complex and sophisticated designs are required as the frequency band increases.

[0004] Conventional array antennas primarily adjusted the phase and power of the signal through power distribution networks and phase converters. However, in the millimeter-wave band, this approach has limitations, such as being complex, having high power loss, limiting bandwidth, and making system miniaturization difficult. The problem to be solved

[0005] The millimeter wave band is attracting attention in next-generation communication systems, such as 5G, 6G, and beyond, as it enables ultra-high-speed data transmission. However, due to the radio propagation characteristics of millimeter waves—which have short wavelengths and strong directivity resulting in high path loss—the popularization of Beyond 5G (B5G) and 6G millimeter wave (mmWave) band wireless communication has not been achieved. It was expected that this could be overcome through beam steering, which selectively delivers high radio energy to user devices. However, there is a problem in that installing small fixed wireless access networks equipped with expensive beam steering phased array antennas at high densities requires astronomical costs.

[0006] Along with wireless communication, the demand for sensing technology utilizing radio waves is also gradually expanding. The core of radio wave sensing is radar, and multi-functional array antenna technology, which can improve detection probability even in complex cluttered environments through beam steering capabilities, is attracting attention as a key technology. Unlike in the past when radar was primarily applied to large platforms such as military or automotive applications, there is a growing demand for small, lightweight, and low-cost radars that can be mounted on autonomous mobile vehicles such as drones and robots. However, conventional phased array antennas are expensive and bulky, making it difficult to apply them to small autonomous mobile vehicles. means of solving the problem

[0007] To solve the above technical problem, an RF network device according to the first embodiment of the present specification may include at least one phase shifter that changes the phase of a signal.

[0008] In the above RF network device, the phase shifter may each include: a first phase shifter that changes the phase of an input RF (radio frequency) signal; a power splitter connected to the rear end of the first phase shifter and equally distributing the RF signal whose phase has been changed by the first phase shifter to both sides; and two second phase shifters each connected to the rear end of the power splitter and changing the phase of the RF signal distributed by the power splitter.

[0009] In the above RF network device, the first phase shifter and the second phase shifter may each include a varactor diode whose capacitance changes according to voltage; and an RF choke configured with a radial stub structure to block RF signal transmission to a DC voltage source.

[0010] In the above RF network device, the phase shifter may further include a DC block configured with an interdigitated band-pass filter structure to block the transmission of a DC signal to an RF signal source.

[0011] A distributed diode network array antenna configured with a stacked structure according to the second embodiment of the present specification may include: an antenna layer; a DC network layer which is a diode control network; and an RF network layer in which distribution and phase shifting of an RF (radio frequency) signal are performed.

[0012] In the above distributed diode network array antenna, the RF network layer may include at least one phase shifter that changes the phase of a signal.

[0013] In the above distributed diode network array antenna, the phase shifter may each include: a first phase shifter that changes the phase of an input RF (radio frequency) signal; a power splitter connected to the rear end of the first phase shifter and equally distributing the RF signal whose phase has been changed by the first phase shifter to both sides; and two second phase shifters each connected to the rear end of the power splitter and changing the phase of the RF signal distributed by the power splitter.

[0014] In the above distributed diode network array antenna, the first phase shifter and the second phase shifter may each include a varactor diode whose capacitance changes according to voltage; and an RF choke configured with a radial stub structure to block RF signal transmission to a DC voltage source. Effects of the invention

[0015] The invention according to one embodiment of this specification relates to an active surface structure array antenna. Unlike conventional phased array antennas composed of multiple stages of expensive integrated circuit (IC) chips, this invention has the advantage of enabling not only beam steering but also polarization conversion, nulling, and beam focusing by controlling inexpensive active components (e.g., PIN diodes, varactor diodes, etc.) mounted on an ultra-thin planar structure. Furthermore, this enables the implementation of an economical and free multi-functional array antenna by freeing from the intellectual property restrictions of integrated circuit chips.

[0016] In addition, a distributed diode network array antenna according to another embodiment of the present specification can drastically reduce the number of varactor diodes used compared to the case where a conventional two-stage phase shifter is used by positioning a phase shifter in front of the power divider. Brief explanation of the drawing

[0017] The accompanying drawings, included as part of the detailed description to aid in understanding the present specification, provide embodiments of the present specification and explain the technical features of the present specification together with the detailed description. FIG. 1 is a block diagram showing a distributed diode network array antenna according to an embodiment of the present specification. FIG. 2 is a diagram showing an example of a distributed diode network array antenna according to an embodiment of the present specification. FIG. 3 is a drawing showing an RF network device according to an embodiment of the present specification. FIG. 4 is a drawing showing an example of an RF network device according to an embodiment of the present specification. Figure 5 is a diagram showing a conventional two-stage phase shifter structure and an intermediate stage phase shifter structure. Figure 6 is a diagram showing an example to explain RF choke and DC block. Specific details for implementing the invention

[0018] Embodiments of the present specification will be described in detail below with reference to the drawings. However, detailed descriptions of known functions or configurations that may obscure the essence of the embodiments in the following description and the attached drawings are omitted. Additionally, throughout the specification, the term 'comprising' a component means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0019] The terms used herein are merely for describing specific embodiments and are not intended to limit the specification. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, terms such as “comprising” or “comprising” are intended to specify the existence of the described features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0020] Unless specifically defined otherwise, 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 specification pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this specification.

[0021] FIG. 1 is a block diagram showing a distributed diode network array antenna according to an embodiment of the present specification.

[0022] Referring to FIG. 1, a distributed diode network array antenna (10) may include an antenna layer (100) capable of transmitting and receiving radio waves; a DC network layer (200) which is a diode control network; and an RF network layer (300) in which the distribution and phase shifting of RF (radio frequency) signals take place. An example of the overall structure of the distributed diode network array antenna (10) is shown in FIG. 2.

[0023] FIG. 2 is a diagram showing an example of a distributed diode network array antenna according to an embodiment of the present specification.

[0024] Referring to FIG. 2, the distributed diode network array antenna (10) may be configured as a stacked structure consisting of the antenna layer (100), the DC network layer (200), and the RF network layer (300) in that order, and may further include a ground plane between the antenna layer (100) and the DC network layer (200).

[0025] Referring to the antenna layer (100) of FIG. 2, it can be seen that the distributed diode network array antenna (10) is implemented to have 4 x 4 = 16 antennas. At this time, the number of antennas is merely an example for explaining the distributed diode network array antenna (10) according to the embodiment of the present specification and is not limited thereto.

[0026] In a distributed diode network array antenna (10), the antenna layer (100), the ground plane, the DC network layer (200), and the RF network layer (300) can each be designed with High-Temperature Co-fired Ceramic (HTCC).

[0027] HTCC has the advantages of high dielectric constant and low dielectric loss, and unlike general PCB materials which have limitations in thickness control, it can provide more freedom in controlling the thickness of each layer. When using HTCC, each layer can be designed with a thin thickness of about 0.1 mm, and there is also the advantage that thin layers can increase the cutoff frequency of surface waves, thereby reducing the number of spurious modes.

[0028] For example, in a distributed diode network array antenna (10), the antenna layer (100) can be designed to have a thickness of 0.65 mm, the ground plane (400) 0.1 mm, and the DC network layer (200) 0.2 mm.

[0029] In the distributed diode network array antenna (10), the RF network layer (300) may be composed of an RF network device according to an embodiment of the present specification, and a detailed description of the RF network device is provided below in the drawings.

[0030] FIG. 3 is a drawing showing an RF network device according to an embodiment of the present specification.

[0031] Referring to FIG. 3, the RF network device (300) may include a power divider that distributes the RF signal evenly to both sides and a phase shifter that changes the phase of the RF signal. At this time, the RF network device may optionally further include an RF choke that blocks the RF signal from being transmitted to a DC voltage source and a DC block that blocks the DC signal from being transmitted to an RF signal source. A detailed description of the RF choke and the DC block will be supplemented in FIG. 4 and FIG. 6.

[0032] The RF network device may include at least one phase shifter (310).

[0033] The above phase shift unit (310) may each include: a first phase shifter (330) that changes the phase of an input RF signal; a power splitter (350) connected to the rear end of the first phase shifter (330) and distributing the RF signal whose phase has been changed by the first phase shifter (330) equally to both sides; and two second phase shifters (370) each connected to the rear end of the power splitter (350) and changing the phase of the RF signal distributed by the power splitter (350). Refer to FIG. 4 for a detailed description of the RF network device (300).

[0034] FIG. 4 is a drawing showing an example of an RF network device according to an embodiment of the present specification.

[0035] The RF network device shown in FIG. 4 is an exemplary RF network device in which the number of antennas is 16, and the RF network device (300) according to the embodiment of the present specification may be configured differently depending on the change in the number of antennas.

[0036] Referring to FIG. 4, a high-frequency signal input from a single feed unit is transmitted to a power splitter along an RF line and is evenly distributed into 16 output signals according to the number of antennas through the power splitter. The phase shifter (310) can change the phase of the distributed high-frequency signal. At this time, the high-frequency signal may include Ka-band, mmWave signals, and RF signals.

[0037] For a detailed explanation of the above phase transition unit (310), refer to FIG. 5 for a moment.

[0038] Figure 5 is a diagram showing a conventional two-stage phase shifter structure and an intermediate stage phase shifter structure.

[0039] Referring to part (a) of Fig. 5, one can see the structure of a conventional two-stage phase shifter. The conventional two-stage phase shifter structure requires two phase shifters to change the phase of the high-frequency signal within the range of 0 to 360 degrees. Therefore, four phase shifters are required to change the phase of the signal input to the two antennas.

[0040] On the other hand, the RF network device (300) according to the embodiment of the present specification can change the phase of the signal input to two antennas in the range of 0 to 360 degrees using only three phase shifters by positioning an intermediate phase shifter (i.e., a first phase shifter) in front of the power splitter.

[0041] In other words, for an array antenna with n antennas, an array antenna using a conventional 2-stage phase shifter structure requires 2n phase shifters, whereas an array antenna using an intermediate-stage phase shifter structure can achieve the same effect with only 1.5n phase shifters, thereby drastically reducing the volume of the array antenna. The intermediate-stage phase shifter structure can be seen in Fig. 5 (c).

[0042] In the above phase shift unit (310), the first phase shifter (330) and the second phase shifter (370) each refer to a phase shifter connected to the front and rear ends of the power distributor (350), and can be configured with the same structure.

[0043] Referring to Fig. 5(c), the first phase shifter (330) corresponds to the 'Intermediate phase shifter' part, and the second phase shifter (370) corresponds to the 'Independent phase shifter' part.

[0044] Through the first phase shifter (330), the RF signal controls the phases of the RF signals distributed into two branches by the power splitter (350) to be identical, thereby creating dependency between the distributed RF signals. The second phase shifter (370) controls the phases of each distributed RF signal independently.

[0045] Referring again to FIG. 4, the first phase shifter (330) and the second phase shifter (370) may each include a varactor diode whose capacitance changes according to voltage; and an RF choke that blocks the transmission of an RF signal to a DC voltage source. In this case, the first phase shifter (330) and the second phase shifter (370) may each be composed of three varactor diodes.

[0046] Since the above phase shift unit (310) is configured as an intermediate phase shifter structure, the RF network device according to the embodiment of the present specification can achieve the same effect by using only 25% fewer varactor diodes compared to the case where a conventional two-stage phase shifter structure is used.

[0047] The above varactor diode is a device whose capacitance changes according to the DC bias voltage, and the DC bias voltage is transmitted through vias in the DC network layer (200).

[0048] In high-frequency bands, including Ka-band, mmWave, and RF signals, signal loss can increase and frequency can change due to parasitic components in the components used in array antennas. Therefore, it is important to select components for array antennas by considering parasitic inductance in high-frequency bands.

[0049] When using varactor diodes in an array antenna, parasitic inductance can be offset by selecting a varactor diode with low variable capacitance. Accordingly, it is important to select a varactor diode model with a capacitance low enough to offset parasitic inductance in the Ka-band through phase shift analysis of the signal, and it has been confirmed that the MAVR-011020-1411 model has sufficiently low capacitance. As an embodiment according to this, the varactor diodes of the first phase shifter (330) and the second phase shifter (370) may be the MAVR-011020-1411 model.

[0050] The above RF choke refers to a component used to prevent RF signals from being transmitted to a DC voltage source. In the case of array antennas in the low-frequency band, chip inductors can be used as RF choke components; however, in the case of high-frequency bands, there are limitations on using chip inductors due to self-resonance caused by the paracite effect. To overcome these limitations, the RF network device according to the embodiment of this specification implements the RF choke as a radial stub structure and integrates it into a phase shifter. A detailed description of the radial stub structure of the RF choke will be supplemented in FIG. 6 along with the DC block.

[0051] Referring to the 'DC block' portion of FIG. 4, the phase shift unit (310) may further include a DC block that blocks the transmission of a DC signal to an RF signal source.

[0052] A DC block refers to a component used to prevent a DC signal from being transmitted to an RF signal source. While chip capacitors are primarily used as DC blocks for array antennas in the low-frequency band, the DC block is implemented using an interdigitated band-pass filter structure for operation in the high-frequency band. Refer to Fig. 6 to explain the radial stub structure of the RF choke and the interdigitated band-pass filter structure of the DC block.

[0053] Figure 6 is a diagram showing an example to explain RF choke and DC block.

[0054] Referring to FIG. 6, the principle of blocking RF signals and DC signals, respectively, using the RF choke of the radial stub structure and the DC block of the interconnected band filter structure is shown in an equivalent circuit diagram.

[0055] A ground connection is required for varactor biasing, which is the process of applying voltage to control the capacitance of a varactor diode. In this case, an inductor must be added to the existing DC block to prevent performance degradation caused by parasitic components in high-frequency bands such as mmWave, RF signals, and the Ka-band.

[0056] Referring to the 'Interdigital band-pass filter' section of FIG. 6, the RF network device (300) according to the embodiment of the present specification has the advantage of not requiring an inductor by implementing the DC block as an interconnected band-pass filter structure, and additionally being able to filter out-of-band interference.

[0057] Referring to the 'Radial stub' section of FIG. 6, the RF choke may be configured with a radial stub structure to minimize interference of the RF signal. In this case, the RF choke may be configured by connecting two radial stub structures of the same shape side by side. Explanation of the symbols

[0058] 10: Distributed diode network array antenna 100: Antenna layer 200: DC network layer 300: RF network layer or RF network device 310: Phase Shift Section 330: First Phase Shift Era 350: Power divider 370: Second phase shifter

Claims

Claim 1 An RF network device comprising at least one phase shifter for changing the phase of a signal; wherein each of the phase shifters comprises: a first phase shifter for changing the phase of an input RF (radio frequency) signal; a power splitter connected to the downstream end of the first phase shifter for distributing the RF signal, whose phase has been changed by the first phase shifter, equally to both sides; and two second phase shifters each connected to the downstream end of the power splitter for changing the phase of the RF signal distributed by the power splitter; wherein the first phase shifter controls the phase of the RF signal prior to distribution by the power splitter in common, and each of the two second phase shifters independently controls the phase of each RF signal distributed by the power splitter. Claim 2 An RF network device according to claim 1, wherein the first phase shifter and the second phase shifter each comprise: a varactor diode whose capacitance changes according to voltage; and an RF choke configured with a radial stub structure to block RF signal transmission to a DC voltage source. Claim 3 An RF network device according to claim 1, wherein the phase shifter comprises a DC block configured as an interdigitated band-pass filter structure to block the transmission of a DC signal to an RF signal source. Claim 4 A distributed diode network array antenna configured with a stacked structure comprises: an antenna layer; a DC network layer which is a diode control network; and an RF network layer in which distribution and phase shifting of an RF (radio frequency) signal are performed; wherein the RF network layer comprises at least one phase shifter for changing the phase of a signal; and wherein each of the phase shifters comprises: a first phase shifter for changing the phase of an input RF (radio frequency) signal; and a power divider connected to the downstream end of the first phase shifter and distributing the RF signal, whose phase has been changed by the first phase shifter, equally to both sides. A distributed diode network array antenna comprising: two second phase shifters each connected to the downstream end of the power divider and each changing the phase of an RF signal distributed by the power divider; wherein the first phase shifter jointly controls the phase of the RF signal prior to distribution by the power divider, and each of the two second phase shifters independently controls the phase of each RF signal distributed by the power divider. Claim 5 In claim 4, the first phase shifter and the second phase shifter each comprise: a varactor diode whose capacitance changes according to voltage; and an RF choke configured with a radial stub structure to block RF signal transmission to a DC voltage source, wherein the distributed diode network array antenna comprises

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