Patent Publication Number: US-2022216620-A1

Title: Circularly Polarized Array Antenna for Millimeter Wave Communications

Description:
PRIORITY CLAIM 
     The present application claims the benefit of priority of U.S. Provisional App. No. 63/134,900, titled “Circularly Polarized Array Antenna for Millimeter Wave Communications” and having a filing date of Jan. 7, 2021, which is incorporated by reference herein. 
    
    
     FIELD 
     The present disclosure relates generally to phased array antennas. More particularly, the present disclosure relates to a circularly polarized array antenna for millimeter wave communications. 
     BACKGROUND 
     Antenna systems configured for millimeter-wave communications (e.g., 5th generation mobile communications) can include a phase shifter circuit and a phased array antenna electrically coupled to the phase shifter circuit. The phase shifter circuit can alter a phase of a RF signal received from a RF source such that a phase of the RF signal measured at an output of the RF phase shifter circuit is different relative to a phase of the RF signal measured at an input of the RF phase shifter circuit. In this manner, the RF phase shifter circuit can control a phase shift of the RF signal to steer a radiation pattern associated with the phased array antenna. 
     SUMMARY 
     Aspects and advantages of embodiments of the present disclosure will be set forth in part in the following description, or may be learned from the description, or may be learned through practice of the embodiments. 
     In one aspect, a circularly polarized array antenna is provided. The circularly polarized array antenna includes a ground plane and a plurality of circularly polarized antennas. Each of the circularly polarized antennas is configured to communicate over a frequency band ranging from 24 gigahertz (GHz) to 52 GHz. Each of the circularly polarized antennas includes a column substrate coupled to the ground plane. The column substrate includes a plurality of faces. Each of the circularly polarized antennas further includes a plurality of isolated magnetic dipole elements. Each of the isolated magnetic dipole elements is disposed on a different face of the column substrate. 
     In another aspect, an antenna system is provided. The antenna system includes a phase shifter circuit. The phase shifter circuit includes a plurality of phase shifters. Each of the phase shifters is electrically coupled to a radio frequency (RF) source. The antenna system further includes a circularly polarized array antenna. The circularly polarized array antenna is electrically coupled to the phased shifter circuit. The circularly polarized array antenna includes a ground plane and a plurality of circularly polarized antennas. Each of the circularly polarized antennas is configured to communicate over a frequency band ranging from 24 gigahertz (GHz) to 52 GHz. Each of the circularly polarized antennas includes a column substrate coupled to the ground plane. The column substrate includes a plurality of faces. Each of the circularly polarized antennas further includes a plurality of isolated magnetic dipole elements. Each of the isolated magnetic dipole elements is disposed on a different face of the column substrate. 
     These and other features, aspects and advantages of various embodiments will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the description, serve to explain the related principles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Detailed discussion of embodiments directed to one of ordinary skill in the art are set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  depicts a block diagram of components of an antenna system according to example embodiments of the present disclosure. 
         FIG. 2  depicts a circularly polarized array antenna according to example embodiments of the present disclosure. 
         FIG. 3  depicts components of a circularly polarized antenna of a circularly polarized array antenna according to example embodiments of the present disclosure. 
         FIG. 4  depicts a schematic of the circularly polarized antenna of  FIG. 3  according to example embodiments of the present disclosure. 
         FIG. 5  depicts components of a circularly polarized antenna of a circularly polarized array antenna according to example embodiments of the present disclosure. 
         FIG. 6  depicts a schematic of the circularly polarized antenna of  FIG. 5  according to example embodiments of the present disclosure. 
         FIG. 7  depicts a graphical illustration of a radiation pattern associated with a circularly polarized array antenna according to example embodiments of the present disclosure. 
         FIG. 8  depicts a graphical illustration of an axial ratio associated with a radiation pattern of a circularly polarized array antenna according to example embodiments of the present disclosure. 
         FIG. 9  depicts a graphical illustration of gain associated with first and second radiation patterns of a circularly polarized array antenna according to example embodiments of the present disclosure. 
         FIG. 10  depicts a block diagram of components of another antenna system according to example embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the embodiments, not limitation of the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the scope or spirit of the present disclosure. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that aspects of the present disclosure cover such modifications and variations. 
     Phased array antennas include a plurality of antenna cells. Each of the plurality of antenna cells can be electrically coupled to a phase shifter circuit. The phase shifter circuit can be configured to control a phase shift associated with a RF signal provided to the phased array antenna. By controlling the phase shift associated with the RF signal, a radiation pattern associated with the phased array antenna can be steered without physically moving one or more of the antenna cells. 
     Example aspects of the present disclosure are directed to a circularly polarized array antenna for millimeter wave communications. The circularly polarized array antenna can include a plurality of circularly polarized antennas. For instance, in some implementations, the circularly polarized array antenna can include 128 circularly polarized antennas. In alternative implementations, the circularly polarized array antenna can include more or fewer circularly polarized antennas. Each of the circularly polarized antennas can be configured to communicate over a frequency band associated with millimeter wave communications (e.g., about 24 GHz to about 52 GHz). Details of the circularly polarized antennas will now be discussed in more detail. 
     Each of the circularly polarized antennas can include a column substrate coupled to a ground plane. The column substrate can include a plurality of faces. For instances, in some implementations, the column substrate can include four separate faces (e.g., a first face, a second face, a third face, and a fourth face). In alterative implementations, the column substrate can include more or fewer faces. 
     Each of the circularly polarized antennas can further include a plurality of isolated magnetic dipole elements. Furthermore, each of the isolated magnetic dipole elements can be disposed on a different face of the column substrate. For instance, in some implementations, each of the circularly polarized antennas can include four isolated magnetic dipole elements. In such implementations, a first isolated magnetic dipole element can be disposed on a first face of the column substrate, a second isolated magnetic dipole element can be disposed on a second face of the column substrate, a third isolated magnetic dipole element can be disposed on a third face of the column substrate, and a fourth isolated magnetic dipole element can be disposed on a fourth face of the column substrate. 
     Each of the isolated magnetic dipole elements can be electrically coupled to an RF source via a phase shifter circuit. In this manner, a RF signal generated by the RF source can be provided to each of the isolated magnetic dipole elements via the phase shifter circuit. Furthermore, the phase shifter circuit can be configured to adjust a phase angle associated with the RF signal. In this manner, the phase angle of the RF signal provided to each of the isolated magnetic dipole elements can be different. For instance, in some implementations, the phase shifter circuit can provide a first RF signal to a first isolated magnetic dipole element, a second RF signal to a second isolated magnetic dipole element, a third RF signal to a third isolated magnetic dipole element, and a fourth RF signal to a fourth isolated magnetic dipole element. The second RF signal can be 90 degrees out-of-phase relative to the first RF signal. The third RF signal can be 180 degrees out-of-phase relative to the first RF signal. The fourth RF signal can be 270 degrees out-of-phase relative to the first RF signal. 
     In some implementations, each of the circularly polarized antennas can include a parasitic element. The parasitic element can be electromagnetically coupled with a corresponding isolated magnetic dipole element. In this manner, the electromagnetic coupling between the parasitic element can allow each of the circularly polarized antennas to be tuned to at least a first frequency on the frequency band and a second frequency on the frequency band. For instance, in some implementations, the first frequency can be about 28 GHz, whereas the second frequency can be about 39 GHz. 
     The circularly polarized array antenna according to example aspects of the present disclosure provides numerous technical effects and benefits. For instance, the circularly polarized array antenna can provide radiation patterns that are circularly polarized (e.g., left-hand circularly polarized, right-hand circularly polarized) on the frequency band associated with millimeter wave communications. 
     As used herein, the use of the term “about” in conjunction with a numerical value is intended to refer to within 20% of the stated amount. In addition, the terms “first” and “second” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     Referring now to the FIGS.,  FIG. 1  depicts an antenna system  100  according to example embodiments of the present disclosure. As shown, the antenna system  100  can include a RF phase shifter circuit  110  and a circularly polarized array antenna  120 . The RF phase shifter circuit  110  can include a plurality of millimeter wave phase shifters  112 . Each of the millimeter wave phase shifters  112  can be electrically coupled to a RF source  130 . In this manner, each of the millimeter wave phase shifters  112  can receive a RF signal from the RF source  130 . The RF signal can be associated with millimeter wave communications. In this manner, a frequency of the RF signal can range from about 24 GHz to about 52 GHz. For instance, in some implementations, the frequency of the RF signal can range from 24 GHz to 30 GHz. In alternative implementations, the frequency of the RF signal can range from 30 GHz to 40 GHz. It should be understood that each of the millimeter wave phase shifters  112  can be configured to control a phase shift of the RF signal received from the RF source  130 . In this manner, the radiation pattern of RF waves emitted via the circularly polarized array antenna  120  can be steered without physically moving one or more circularly polarized antennas  200  of the circularly polarized array antenna  120 . 
     The antenna system  100  can include one or more control devices  140 . The one or more control devices  140  can be communicatively coupled to the circularly polarized array antenna  120 . In this manner, the one or more control devices  140  can be configured to control one or more circularly polarized antennas  200  of the circularly polarized array antenna  120  to steer a radiation pattern associated with the circularly polarized array antenna  120  along at least one of an azimuth plane or an elevation plane. 
     Furthermore, in some implementations, the one or more control devices  140  can be communicatively coupled to the RF phase shifter circuit  110 . In this manner, the one or more control devices  140  can be configured to control the millimeter wave phase shifters  112  thereof to steer the radiation pattern of the circularly polarized array antenna  120  along at least one of the azimuth plane or the elevation plane. 
     As shown, the one or more control devices  140  can include one or more processors  142  and one or more memory devices  144 . The one or more processors  142  can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, logic device, or other suitable processing device. The one or more memory devices  144  can include one or more computer-readable media, including, but not limited to, non-transitory computer-readable media, RAM, ROM, hard drives, flash drives, or other memory devices. 
     The one or more memory devices  144  can store information accessible by the one or more processors  142 , including computer-readable instructions that can be executed by the one or more processors  142 . The computer-readable instructions can be any set of instructions that, when executed by the one or more processors  142 , cause the one or more processors  142  to perform operations. The computer-readable instructions can be software written in any suitable programming language or may be implemented in hardware. In some implementations, the computer-readable instructions can be executed by the one or more processors to cause the one or more processors to perform operations, such as controlling the circularly polarized antennas  200  of the circularly polarized array antenna  120 . Additionally, the operations can include controlling one or more millimeter wave phase shifters  112  of the RF phase shifter circuit  110 . 
     Referring now to  FIG. 2 , an example embodiment of the circularly polarized array antenna  120  is provided according to example embodiments of the present disclosure. As shown, in some implementations, the circularly polarized array antenna  120  can include a ground plane  125 . In some implementations, a length dimension  127  of the ground plane  125  can be substantially the same (e.g., within about 10 millimeters) as a width dimension  129  of the ground plane  125 . In alternative implementations, the length dimension  127  of the ground plane  125  can be different (e.g., longer, shorter) than the width dimension  129  of the ground plane  125 . 
     As shown, in some implementations, the circularly polarized array antenna  120  can include 4 circularly polarized antennas  200  arranged on the ground plane  125  in a row-column configuration. For instance, the row-column configuration can include 2 rows of circularly polarized antennas  200  and 2 columns of circularly polarized antennas  200 . It should be understood that, in alternative implementations, the circularly polarized array antenna  120  can include more or fewer circularly polarized antennas  200 . Details of the circularly polarized antennas  200  will now be discussed in more detail. 
     Referring now to  FIGS. 3 and 4 , an example embodiment of a circularly polarized antenna  200  of the circularly polarized array antenna  120  ( FIG. 2 ) is provided. As shown, the circularly polarized antenna can include a column substrate  210 . The column substrate  210  can be disposed on the ground plane  125  ( FIG. 2 ) of the circularly polarized array antenna  120  ( FIG. 2 ). In some implementations, a height  212  of the column substrate  210  can be shorter than the length dimension  127  ( FIG. 2 ) of the ground plane  125  and the width dimension  129  of the ground plane  125 . As shown, the column substrate  210  can include a plurality of faces. For instance, in some implementations, the column substrate  210  can include a first face  220 , a second face  222 , a third face  224 , and a fourth face  226 . In alternative implementations, the column substrate  210  can include more or fewer faces. 
     Each of the circularly polarized antennas  200  can include a plurality of isolated magnetic dipole elements  230 . Each of the isolated magnetic dipole elements  230  can be disposed on a different face (e.g., first face  220 , second face  222 , third face  224 , fourth face  226 ) of the column substrate  210 . Furthermore, each of the isolated magnetic dipole elements  230  can be electrically coupled to the RF source  130  ( FIG. 1 ) via the RF phase shifter circuit  110  (FIG. 1). In this manner, a RF signal generated by the RF source  130  can be provided to each of the isolated magnetic dipole elements  230  via the RF phase shifter circuit  110 . 
     In some implementations, the RF phase shifter circuit  110  can provide a first RF signal to the isolated magnetic dipole element  230  disposed on the first face  220  of the column substrate  210 , a second RF signal to the isolated magnetic dipole element  230  disposed on the second face  222  of the column substrate  210 , a third RF signal to the isolated magnetic dipole element  230  disposed on the third face  224  of the column substrate  210 , and a fourth RF signal to the isolated magnetic dipole element  230  disposed on the fourth face  226  of the column substrate  210 . The second RF signal can be 90 degrees out-of-phase relative to the first RF signal. The third RF signal can be 180 degrees out-of-phase relative to the first RF signal. The fourth RF signal can be 270 degrees out-of-phase relative to the first RF signal. 
     In some implementations, the isolated magnetic dipole element  230  can include a bent conductor. As shown, the bent conductor can include a bottom portion  302  that can be coupled to the RF phase shifter circuit  110  ( FIG. 1 ). In addition, the bottom portion  302  can include one or more ground connections  304 ,  306 . The bent conductor can include a pair of vertical portions extending from opposing ends of the bottom portion  302  For instance, the bent conductor can include a first vertical portion  308  extending from a first end of the bottom portion  302  and a second vertical portion  310  extending from a second end of the bottom portion  302 . The bent conductor can further include a first horizontal portion  312  and a second horizontal portion  314 . The first horizontal portion  312  can extend from a distal end (e.g. farthest from bottom portion  302 ) of the first vertical portion  308 . The second horizontal portion  314  can extend from a distal end of the second vertical portion  310 . As shown, the first horizontal portion  312  and the second horizontal portion  314  can overlap with one another to form a capacitive region R C  therebetween. In addition, the bottom portion  302 , first vertical portion  308 , second vertical portion  310 , first horizontal portion  312 , and second horizontal portion  314  can collectively form a loop about which an inductive region R i  is formed. 
     Referring now to  FIGS. 5 and 6 , another example embodiment of a circularly polarized antenna  200  of the circularly polarized array antenna  120  ( FIG. 2 ) is provided. The circularly polarized antenna  200  can be configured in substantially the same manner as the circularly polarized antenna  200  discussed above with reference to  FIGS. 3 and 4 . For instance, the circularly polarized antenna  200  can include the column substrate  210  and the plurality of isolated magnetic dipole elements  230 . In addition, the circularly polarized antenna  200  of  FIGS. 5 and 6  can include a plurality of parasitic elements  240 . Details of the parasitic elements  240  will now be discussed in more detail. 
     As shown, each of the parasitic elements  240  can be disposed on a different face (e.g., first face  220 , second face  222 , third face  224 , fourth face  226 ) of the column substrate  210 . Each of the parasitic elements  240  can be electromagnetically coupled with a corresponding isolated magnetic dipole element  230 . In this manner, the electromagnetic coupling between the parasitic element  240  and the corresponding isolated magnetic dipole element  230  can allow the circularly polarized antenna  200  to be tuned to at least a first frequency on the frequency band and a second frequency on the frequency band. For instance, in some implementations, the first frequency can be about 28 GHz, whereas the second frequency can be about 39 GHz. 
     In some implementations, the parasitic element  240  can be integral with the corresponding isolated magnetic dipole element  230 . For instance, as shown in  FIG. 6 , the parasitic element  240  and corresponding isolated magnetic dipole element  230  can be configured as a bent conductor configured in substantially the same manner as the bent conductor discussed above with reference to  FIG. 4 . As shown, the parasitic element  240  can include a vertical portion  400  extending from the bottom portion  302  of the bent conductor. In addition, the parasitic element  240  can include a horizontal portion  402  extending from a distal end (e.g., farthest from bottom portion  302  of bent conductor) of the vertical portion  400   
     Referring now to  FIG. 7 , a radiation pattern  500  associated with the circularly polarized array antenna  120  ( FIG. 2 ) is provided according to example embodiments of the present disclosure. It should be appreciated that the ground plane  125  prevents backpropagation of the radiation pattern  500 . In this manner, the radiation pattern  500  is directed away from the ground plane  125  of the polarized array antenna  120 . 
     Referring now to  FIG. 8 , a graphical illustration of an axial ratio associated with a radiation pattern of the circularly polarized array antenna is provided according to example embodiments of the present disclosure. As shown, the axial ratio is depicted as a function of an angle. The axial ratio is denoted along the vertical axis in decibels (dB), and the angle is denoted along the horizontal axis in degrees. As shown, the axial ratio is substantially equal to zero when the angle corresponds to zero degrees. It should be appreciated that an angle of zero degrees corresponds to a zenith axis associated with a radiation pattern of the circularly polarized antenna. 
     Referring now to  FIG. 9 , a graphical illustration of gain associated with a first radiation pattern  600  (e.g., left-hand circularly polarized) associated with the circularly polarized array antenna and a second radiation pattern  610  (e.g., left-hand circularly polarized) associated with the circularly polarized array antenna. As shown, the gain is depicted as a function of an angle. The gain is denoted along the vertical axis in decibels (dB), and the angle is denoted along the horizontal axis in degrees. 
     Referring now to  FIG. 10 , another antenna system  700  is provided according to example embodiments of the present disclosure. It should be understood that the antenna system  700  can be configured in substantially the same manner as the antenna system  100  discussed above with reference to  FIG. 1 . For instance, the antenna system  700  can include the RF phase shifter circuit  110  and the circularly polarized array antenna  120 . 
     Furthermore, in contrast to the antenna system  100  of  FIG. 1 , the antenna system  700  of  FIG. 10  can include an amplitude control circuit  114 . The amplitude control circuit  114  can include a plurality of amplifiers  115 . Each of the amplifiers  115  can be electrically coupled to a corresponding millimeter wave phase shifter  112  of the RF phase shifter circuit  110  and a corresponding circularly polarized antenna  200  of the circularly polarized array antenna  120 . In this manner, each of the amplifiers  115  can amplify a phase-shifted RF signal received from the corresponding millimeter wave phase shifter  112  and provide an amplified phase-shifted RF signal to the corresponding circularly polarized antenna  200 . 
     In some implementations, the one or more control devices  140  can be communicatively coupled to the amplitude control circuit  114 . For instance, the one or more control devices  140  can be communicatively coupled to each of the amplifiers  115 . In this manner, the one or more control devices  140  can independently control operation each of the amplifiers  115 . For instance, in some implementations, the one or more control devices  140  can control operation of the amplifiers  115  such that only a subset of the plurality of phase-shifted RF signals the amplitude control circuit  114  receives from the RF phase shifter circuit  110  are amplified. In alternative implementations, the one or more control devices  140  can control operation of the amplifiers  115  such that each of the phase-shifted RF signals the amplitude control circuit  114  receives from the RF phase shifter circuit  110  are amplified. 
     While the present subject matter has been described in detail with respect to specific example embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.