Patent Application
20220302601
The present disclosure relates to an antenna system, and more particularly, to an antenna system capable of antenna beam steering and impedance control using an active radiation layer capable of individually controlling each unit.
Recently, there is a tendency toward increased operating frequency in not only mobile communication but also many applications. As the frequency increases, signal loss increases with the increasing movement distance, and thus an array antenna including multiple radiators (patch antenna) is widely used to increase antenna gain. The array antenna can improve the antenna gain through constructive interference between the radiators.
In general, an array antenna system controls the output direction of an antenna beam by controlling the phase of waves fed to the radiators. A feed line and a phase shifter individually connected for each radiator are necessary to implement a beam steering system, for example, a radio frequency integrated circuit (RFIC) beamforming circuit. Additionally, an impedance mismatch caused by the antenna external factor may reduce the antenna gain and output properties, so an impedance tuner is necessary to solve the impedance mismatch of each radiator.
However, as the number of radiators increases, the array antenna structure has an increase in the number of components (the respective feed line, phase shifter and impedance tuner) of the beamforming circuit, causing very high power consumption and radio frequency (RF) losses. Accordingly, there is a need for an array antenna system capable of antenna beam steering and impedance control without high power consumption or losses.
The present disclosure is directed to providing an array antenna system capable of beam steering and impedance control through antenna reconfiguration without a phase shifter or an impedance tuner used in a radio frequency integrated circuit (RFIC) beamforming circuit.
An array antenna system according to an embodiment of the present disclosure includes an active radiation layer including a plurality of unit cells and a control circuit to control properties of each unit cell, a plurality of patch antennas placed on each unit cell, and a feed line to feed waves for excitation of the plurality of patch antennas through the active radiation layer, wherein each unit cell is controlled to have different radiation properties by the control circuit, and beam steering and impedance control of the array antenna system is enabled by control of the active radiation layer.
According to an embodiment, the unit cell may include a liquid crystal having varying dielectric constant depending on applied voltage, and the control circuit may control radiation amplitude and phase of each unit cell or control the impedance by independently applying voltage for each unit cell to change the dielectric constant of the liquid crystal.
According to an embodiment, as the dielectric constant of the liquid crystal changes, an effective wavelength of the patch antenna changes, and as the effective wavelength changes, the amplitude and phase of the waves radiating in free space at a particular frequency change.
According to an embodiment, the liquid crystal has an increasing dielectric constant with the increasing applied voltage.
According to an embodiment, the height of each unit cell may be set to a few tens to a few hundreds of μm.
The array antenna system according to an embodiment has the active radiation layer placed below the patch antenna to independently control the radiation properties of each unit cell. According to an embodiment, it is possible to achieve antenna beam steering and impedance control using the active radiation layer. The existing method accomplishes beam steering or solves an impedance mismatch through a phase shifter or an impedance tuner connected for each radiator, but its disadvantage is a significant increase in power consumption and radio frequency (RF) losses with the increasing number of radiators. According to an embodiment, it is possible to achieve beam steering and impedance control using the active radiation layer made of reconfigurable elements and materials without additional RF elements, thereby significantly reducing the power consumption and losses. Additionally, the use of the single feed line reduces the complexity of system design.
The following is a brief introduction to necessary drawings in the description of the embodiments to describe the technical solutions of the embodiments of the present disclosure or the existing technology more clearly. It should be understood that the accompanying drawings are for the purpose of describing the embodiments of the present disclosure and are not intended to be limiting of the present disclosure. Additionally, for clarity of description, illustration of some elements in the drawings may be exaggerated and omitted.
The following detailed description of the present disclosure is made with reference to the accompanying drawings, in which particular embodiments for practicing the present disclosure are shown for illustration purposes. These embodiments are described in sufficiently detail for those skilled in the art to practice the present disclosure. It should be understood that various embodiments of the present disclosure are different but do not need to be mutually exclusive. For example, particular shapes, structures and features described herein in connection with one embodiment may be embodied in other embodiment without departing from the spirit and scope of the present disclosure. It should be further understood that changes may be made to the positions or placement of individual elements in each disclosed embodiment without departing from the spirit and scope of the present disclosure. Accordingly, the following detailed description is not intended to be taken in limiting senses, and the scope of the present disclosure, if appropriately described, is only defined by the appended claims along with the full scope of equivalents to which such claims are entitled. In the drawings, similar reference signs denote same or similar functions in many aspects.
The terms as used herein are general terms selected as those being now used as widely as possible in consideration of functions, but they may vary depending on the intention of those skilled in the art or the convention or the emergence of new technology. Additionally, in certain cases, there may be terms arbitrarily selected by the applicant, and in this case, the meaning will be described in the corresponding description part of the specification. Accordingly, it should be noted that the terms as used herein should be defined based on the meaning of the terms and the context throughout the specification, rather than simply the name of the terms.
Hereinafter, the preferred embodiments of an array antenna system capable of beam steering and impedance control will be described in detail with reference to the accompanying drawings.
The active radiation layer 10 includes the unit cells C1, C2, C3, C4, . . . and the control circuit to control the properties of each unit cell. A unit radiator including each unit cell and a patch antenna placed thereon acts as a metamaterial for the waves. The unit cells C1, C2, C3, C4, . . . include reconfigurable elements or materials (for example, a PIN diode, a varactor, a liquid crystal).
In the specification, the reconfigurable antenna refers to an antenna capable of modifying the operating frequency or radiation properties in a controlled and reversible manner. When the reconfigurable antenna is applied to the array antenna system, it is possible to accomplish beam steering by controlling the radiation properties through antenna reconfiguration without any additional element such as a phase shifter.
The waves going into the left side of the feed line 20 excite the top patch antenna through a slot while traveling to the right side. The antenna radiation layer radiates in the broadside direction through interaction with the waves. The slot may be designed in various shapes, for example, a rectangular shape, an H-shape, an L-shape, and it may be designed to have a plurality of slots for each unit cell. Each patch antenna A1, A2, A3, A4, . . . may be made in various shapes (rectangular, circular, Bowtie, etc.).
According to an embodiment, the unit cells C1, C2, C3, C4, . . . include a liquid crystal having varying dielectric constant depending on the applied voltage, and the control circuit is configured to control the radiation amplitude and phase of each unit cell or control the impedance by independently applying voltage for each unit cell to change the dielectric constant of the liquid crystal.
As shown in
In the above embodiment, the dielectric constant of the liquid crystal may be represented as a function of voltage, and accordingly it is possible to control the dielectric constant of the liquid crystal serving as a substrate of the radiator by independently applying voltage. In other words, it is possible to control the output properties (amplitude and phase) of the patch antenna by applying voltage to the unit cell, thereby controlling the output direction of the beam.
According to the array antenna system described above, it is possible to achieve beam steering and impedance control using the active radiation layer capable of independently control the radiation properties of each unit cell through the single feed line. The existing method accomplishes beam steering or controls an impedance mismatch through a phase shifter or an impedance tuner connected for each radiator, but its disadvantage is a significant increase in power consumption and RF losses with the increasing number of radiators. According to an embodiment, it is possible to achieve beam steering and impedance control without RF components using the active radiation layer made of materials having varying dielectric constant depending on the applied voltage such as the liquid crystal and significantly reduce the power consumption and losses. Additionally, the use of the single feed line reduces the complexity of system design.
While the present disclosure has been hereinabove described with reference to the embodiments, those skilled in the art will understand that various modifications and changes may be made thereto without departing from the spirit and scope of the present disclosure defined in the appended claims.
