This application is based on and claims priority under 35 U.S.C. § 119(a) of a Korean patent application number 10-2019-0095921, filed on Aug. 7, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety.
The disclosure relates to an array antenna. More particularly, the disclosure relates to an array antenna configured by arranging a plurality of antenna elements at very close positions.
In recent, data are exchanged more frequently with an external device using an antenna in a smart phone, a tablet medical device, an Internet of things (IoT) device, and so on, by applying a wireless communication technology. A plurality of antennas is used for wireless fidelity (Wi-Fi), Bluetooth, global positioning system (GPS), and so on, in one device. Using the plurality of the antennas, internal and external signal interference may occur.
In this respect, a technique for nulling or forming an interference signal by use of an array antenna or a technique for mitigating an interference signal by adjusting a weight for each antenna element is widely researched. However, the array antenna including a plurality of an array antenna elements occupies a considerable space, and accordingly there is difficulty in applying it to a device which is getting small.
If the array antenna elements are arranged excessively closely, mutual interference occurs between the array antenna elements and nulling performance may degrade. Such nulling performance degradation is caused by mutual coupling increase between the antennas if a distance between adjacent array antenna elements is very short. In this case, as radiation patterns of the individual elements have high correlations, the pattern nulling or forming performance is degraded and thus spatial diversity of the array antenna also reduces. Hence, what is demanded is a technique for contiguously arranging the array antenna elements and mitigating their interference.
The above information is presented as background information only to assist with an understanding of the disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the disclosure.
Aspects of the disclosure are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the disclosure is to provide an array antenna, and more specifically, the array antenna configured by arranging a plurality of antenna elements at close positions.
Another aspect of the disclosure is to provide an array antenna of a small size by arranging antenna elements at close positions.
Another aspect of the disclosure is to provide an array antenna for minimizing influence of interference in arranging antenna elements at close positions.
Another aspect of the disclosure is to provide an array antenna having a low coupling pattern correlation in arranging antenna elements at close positions.
Another aspect of the disclosure is to provide an array antenna for having high impedance matching in arranging antenna elements at close positions.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.
In accordance with an aspect of the disclosure, an array antenna is provided. The array antenna includes a first antenna operating in a first mode, and a second antenna operating in a second mode, wherein a correlation between an electric field of the first mode and an electric field of the second mode falls below a first threshold which is predetermined, or a correlation between a magnetic field of the first mode and a magnetic field of the second mode falls below a second threshold which is predetermined.
The first antenna may be a monopole antenna, and the second antenna may be a patch antenna of a loop shape.
The electric field of the first mode and the electric field of the second mode may be orthogonal, or the magnetic field of the first mode and the magnetic field of the second mode may be orthogonal.
The array antenna may further include a first weight multiplier for multiplying a signal received using the first antenna by a first weight, a second weight multiplier for multiplying a signal received using the second antenna by a second weight, and an array antenna receiver for calculating a received signal of the array antenna by adding the signal multiplied by the first weight and the signal multiplied by the second weight.
The first weight and the second weight may be updated based on Equation 1.
k+1 is a weight vector of a (k+1)-th iterative calculation,
Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.
The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of various embodiments of the disclosure is provided for illustration purpose only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.
Terms used in the disclosure are used for describing particular embodiments and are not intended to limit the scope of other embodiments. All the terms used herein, including technical and scientific terms, may have the same meanings as terms generally understood by those skilled in the art to which the disclosure pertains. Among terms used in the disclosure, the terms defined in a general dictionary may be interpreted to have the same or similar meanings with the context of the relevant art, and, unless explicitly defined in this disclosure, it shall not be interpreted ideally or excessively as formal meanings. In some cases, even terms defined in this disclosure should not be interpreted to exclude the embodiments of the disclosure.
In various embodiments of the disclosure to be described below, a hardware approach will be described as an example. However, since the various embodiments of the disclosure include a technology using both hardware and software, the various embodiments of the disclosure do not exclude a software-based approach.
Since an array antenna is arranged contiguously and a radiation pattern of individual elements has high correlation, researches are conducted on a technique for minimizing mutual coupling and the pattern correlation of the small array antenna including parasitic element, defected or extended ground planes, electromagnetic band-gap structure and ferrite material use, to address a problem that pattern nulling or forming performance is degraded and spatial diversity of the array antenna also decreases. Such researches may improve insulation and maintain low pattern correlation between adjacent array elements, but may be infeasible in a small device where its space is limited. Hence, researches for mounting the array antenna in the small space have integrated a multi radiation mode of each array element or adopted a different antenna type. However, such researches still need an electric antenna of a great size to achieve a high order mode, and it is hard to control the mutual coupling and the pattern correlation due to a shape of a patch antenna.
To address this problem, the disclosure provides an array antenna, and more specifically, a technique for the array antenna configured by arranging a plurality of antenna elements at very close positions.
The disclosure provides a 2-element array antenna having a very short array distance. Each array element has a modal difference in a radiation pattern, and causes high isolation and low correlation between the arrays.
Terms indicating components of a device, which are used in the following descriptions, are for the sake of explanations. Accordingly, the disclosure is not limited to the terms to be described, and may use other terms having technically identical or similar meaning.
In this disclosure, to determine whether a specific condition is satisfied or fulfilled, expressions such as “greater than” or “less than” are used by way of example and expressions such as “greater than or equal to” or “less than or equal to” are also applicable and not excluded. A condition defined with “greater than or equal to” may be replaced by “greater than” (or vice-versa), and a condition defined with “less than or equal to” may be replaced by “less than” (or vice-versa), etc.
Referring to
The array antenna according to various embodiments of the disclosure may include a first antenna 140 and a second antenna 120. According to various embodiments of the disclosure, a dielectric may be disposed on a substrate 110. The first antenna 140 may be a monopole antenna disposed on the dielectric. The second antenna 120 may be a patch antenna disposed on the substrate 110. Herein, the patch antenna 120 may be a quadrangular loop antenna.
Herein, the loop antenna is rectangular in shape, and includes a shape of different internal and external widths and a rectangular penetrating hole corresponding to the internal width at its center.
Referring to
According to various embodiments of the disclosure, the first antenna 140 may be the monopole antenna which extends vertically to a plane including the patch antenna 120 from the center of the patch antenna which is the second antenna 120.
According to various embodiments of the disclosure, a phase center of the first antenna 140 and a phase center of the second antenna 120 may be in parallel on an axis vertical to the second antenna 120. Since the second antenna 120 is in an x-y plane in
According to various embodiments of the disclosure, the monopole antenna 140 and the patch antenna 120 of the loop type may share ground.
According to various embodiments of the disclosure, by sharing the ground, the antenna ports may be disposed very closely to each other and minimize distortion of antenna performance.
Referring to
Referring to
According to various embodiments of the disclosure, a patch antenna 210 which is a first array element may form a square ring shape of which internal and external widths are w and 1. A monopole antenna 250 which is a second array element is disposed at a center of a ground plate with the thickness t and the length h. A substrate 230 may be interposed between the patch antenna 210 and the monopole antennas 350 and 370.
Referring to
According to various embodiments of the disclosure, mutual coupling and impedance matching characteristics between the first and second arrays may be controlled by adjusting the thickness t and the internal width w which are the array antenna geometric parameters.
According to various embodiments of the disclosure, by sharing the ground 270, the antenna ports may be disposed very closely and minimize distortion of the antenna performance.
Referring to
According to various embodiments of the disclosure, the electric field generated by the monopole antenna 411 may be generated by changing the direction upwards and downwards with time. The first antenna 411 may generate the electric field by operating in a transverse magnetic (TM) wave propagation mode.
Referring to
If the patch antenna 431 is disposed on a dielectric, the electric field may be generated by the patch antenna 431 of the loop shape in a downward direction 443 in view of the dielectric. In this case, the magnetic field may be generated by the patch antenna 431 in parallel with the patch antenna 431 in view of the dielectric.
Comparing the magnetic fields in
According to various embodiments of the disclosure, the magnetic field generated by the first antenna 411 and the magnetic field generated by the second antenna 431 may be orthogonal.
According to various embodiments of the disclosure, a correlation between the electric field generated by the first antenna 411 and the electric field generated by the second antenna 431 may fall below a first threshold which is predetermined. Alternatively, a correlation between the magnetic field generated by the first antenna 411 and the magnetic field generated by the second antenna 431 may fall below a second threshold which is predetermined.
Referring to
According to various embodiments of the disclosure, by adequately determining the weight values multiplied by the signals respectively, a great gain may be given in a particular direction, and a signal incoming in a corresponding direction may be cancelled by forming the null.
According to various embodiments of the disclosure, a weight for determining the beam pattern of the array antenna may be updated through iterative calculation based on Equation 1.
k+1 is a weight vector of a (k+1)-th iterative calculation, and
Referring to
The monopole antenna is modeled in series of resistance Rm, inductance Lm, and capacitance Cm, and the patch antenna is modeled in parallel of resistance Rp, inductance Lp, and capacitance Cp. Hence, the monopole and patch antennas of the array antenna are coupled by coupling capacitance Cc and an inductive coupling coefficient k. The coupling capacitance Cc and the inductive coupling coefficient k may be changed by the geometric parameter h or w of the array antenna. Herein, h indicates the height h of the monopole antenna which is the first antenna, and w indicates the internal width w of the patch antenna which is the second antenna.
Referring to
To more precisely observe the electromagnetic coupling effect of
Referring to
Referring to
Thus, the array antenna of the disclosure may achieve both of the low mutual coupling and the good impedance matching characteristics by adjusting the geometric parameters. For example, each array antenna having the transverse current direction may provide an orthogonal radiation pattern of a low pattern correlation due to clear modal difference between the array antennas.
Referring to
Referring to
In the graphs of
Referring to
Referring to
Referring to
Referring to
Referring to
The patch antenna exhibits a half power beam width at 76.1 degrees and 85.2 degrees in the z-x plane and the z-y plane respectively. The patch antenna obtains the maximum radiation gain at 5 degrees and the patch antenna obtains the maximum radiation gain at 45 degrees.
For example, the 2-element array antenna according to various embodiments of the disclosure may maintain the independent radiation pattern with the high isolation and the low correlation between the array elements even at a narrow array spacing.
Referring to
Referring to
ρECC denotes the envelope correlation coefficient between far-field radiation patterns, and E1(θ, ϕ) denotes the far-field radiation pattern generated by the first antenna. E2(θ, ϕ) denotes the far-field radiation pattern generated by the second antenna, E*1(θ, ϕ) denotes a conjugate complex number of E1(θ, ϕ), and E*2(θ, ϕ) denotes a conjugate complex number of E2(θ, ϕ). θ denotes an azimuth, and ϕ denotes an elevation.
Equation 3 may be re-expressed as Equation 4.
Sif denotes an S parameter of a j-th antenna for an i-th antenna, η1 denotes a radiation efficiency of the first antenna, and η2 denotes a radiation efficiency of the second antenna. Equation 4 expresses Equation 3 by using the scattering S parameter between the antennas. The S parameter is changed in value according to the distance between the antennas.
Hence, Equation 4 is the function based on the distance between the antennas, which may be represented as shown in
Referring to
Referring to
The envelope correlation coefficient of the array antenna including the two patch antennas is not defined below a particular value due to the physical shape of the patch antenna. The envelope correlation coefficient of the array antenna including the two patch antennas approximately reduces as the distance between the antennas increases.
The envelope correlation coefficient of the array antenna including the monopole antenna and the patch antennas according to various embodiments of the disclosure may be defined even for a very small value by placing the two antennas very closely as shown in
Referring to
The 2-element array antenna according to various embodiments of the disclosure may maintain the independent radiation pattern with the high isolation and the low correlation between the array elements even at the narrow array spacing.
Referring to
Referring to
Referring to
Referring to
The disclosed array antenna has the greatest null depth, compared with the monopole and patch array antennas of the relater art.
Referring to
Referring to
Referring to
Thus, since the two-element array has the very short array distance due to the modal difference, the disclosed array antenna may exhibit high null pattern characteristics and achieve low pattern correlation and high isolation.
Referring to
Referring to
Referring to
An apparatus according to various embodiments of the disclosure includes an array antenna in which a plurality of antenna elements is very contiguous, thus minimizing interference and realizing the small array antenna including the contiguous antenna elements.
The method according to the embodiment may be embodied in the form of program instructions which may be executed by various computer means and recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the media may be those specially designed and constructed for the purposes of the embodiments, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of the computer readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical media such as compact disc (CD)-read only memories (ROMs), digital versatile discs (DVDs), and magneto-optical media disks such as floppy disks, and hardware devices specifically configured to store and execute program instructions, such as ROM, random access memory (RAM), flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code which may be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.
Although the embodiments have been described by the limited embodiments and the drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and/or components of the described systems, structures, devices, circuits, etc. may be coupled or combined in a different form than the described method, or an appropriate result may be achieved even if replaced or substituted by other components or equivalents.
While the disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims and their equivalents.
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Number | Date | Country | |
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20210044031 A1 | Feb 2021 | US |