Patent Publication Number: US-11394125-B2

Title: Reconfigurable antenna design for centimeter-wave and millimeter-wave

Description:
GOVERNMENT LICENSE RIGHTS 
     This invention was made with government support under 1253929 awarded by the National Science Foundation. The government has certain rights in the invention. 
    
    
     TECHNICAL FIELD 
     Example embodiments generally relate to antenna technologies and, more particularly, relate to apparatuses, systems, and methods for implementing a dynamically configurable antenna. 
     BACKGROUND 
     There is seemly no end to the desire to increase throughput of information in context of wireless communications. For example, with respect to cellular communications, technology has for merely voice communications to high speed data communications via 4th generation (4G) and now 5th generation (5G) technologies. To facilitate the evolution of these communications technologies, fundamental components of the communications devices must also evolve. Conventionally passive components, such as antennas, must also evolve to support new communications techniques. 
     BRIEF SUMMARY OF SOME EXAMPLES 
     According to some example embodiments, an example apparatus for implementing a reconfigurable antenna is provided. The example apparatus may comprise an antenna assembly. The antenna assembly may comprise an antenna patch array comprising a plurality of antenna patches, and a switch array comprising plurality of switches. Each switch of the plurality switches may be electronically controllable to transition between states comprising a conducting state and a non-conducting state. Additionally, each switch may be electrically connected between two of the antenna patches of the antenna array. The example apparatus may further comprise control circuitry configured to control the states of the switches of the switch array to operate the antenna patch array in a first communications mode at a first wavelength, and control the states of the switches of the switch array to operate the antenna patch array in a second communications mode at a second wavelength. 
     According to some example embodiments, an example method for configuring a reconfigurable antenna is provided. The example method may comprise controlling, via control circuitry, states of switches of a switch array to operate an antenna patch array in a first communications mode at a first wavelength. The antenna patch array may comprise a plurality of antenna patches and the switch array may comprise a plurality of switches. Each switch of the plurality switches may be electronically controllable by the control circuitry to transition between states comprising a conducting state and a non-conducting state. Additionally, each switch may be electrically connected between two of the antenna patches of the antenna array. The example method may further comprise controlling, via control circuitry, the states of the switches of the switch array to operate the antenna patch array in a second communications mode at a second wavelength. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Having thus described some example embodiments in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  illustrates an example communications device according to some example embodiments; 
         FIG. 2  illustrates an example array of antenna patches according to some example embodiments; 
         FIG. 3  illustrates an example array of antenna patches with intermediate switches according to some example embodiments; 
         FIG. 4  illustrates an example antenna assembly according to some example embodiments; 
         FIGS. 5 and 6  shows graphs of beamwidth control according to some example embodiments; 
         FIG. 7  shows a graph of return losses for different switching configurations according to some example embodiments; 
         FIG. 8A  illustrates an array of antenna patches according to some example embodiments; 
         FIG. 8B  shows a graph of return losses of the array of antenna patches of  FIG. 8A  at different gap widths according to some example embodiments; 
         FIG. 9A  illustrates an array of antenna patches with switches according to some example embodiments; 
         FIG. 9B  shows a graph of return losses of the array of antenna patches of  FIG. 9A  at different switch widths according to some example embodiments; 
         FIG. 10A  illustrates an isolated antenna patch with switches according to some example embodiments; 
         FIG. 10B  shows a graph of return losses of the antenna patch of  FIG. 10A  at different switch widths according to some example embodiments; 
         FIG. 11A  illustrates an isolated antenna patch with switches according to some example embodiments; 
         FIG. 11B  shows a graph of return losses of the antenna patch of  FIG. 11A  at different switch widths according to some example embodiments; 
         FIG. 12A  illustrates an array of antenna patches with switches closed according to some example embodiments; 
         FIG. 12B  shows a graph of return losses of the array of antenna patches of  FIG. 12A  at different switch widths according to some example embodiments; 
         FIG. 13A  illustrates an array of antenna patches with switches open according to some example embodiments; 
         FIG. 13B  shows a graph of return losses of the array of antenna patches of  FIG. 13A  at different switch widths according to some example embodiments; 
         FIGS. 14A and 14B  show graphs of beamforming with perfect switch isolation according to some example embodiments; 
         FIGS. 15A and 15B  show graphs of beamforming with imperfect switch isolation according to some example embodiments; 
         FIG. 16  illustrates an example reconfigurable antenna according to some example embodiments; and 
         FIG. 17  illustrates a flow chart of an example method of configuring a reconfigurable antenna according to some example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Some example embodiments now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all example embodiments are shown. Indeed, the examples described and pictured herein should not be construed as being limiting as to the scope, applicability, or configuration of the present disclosure. Rather, these example embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. 
     As used herein the term “or” is used as the logical or where any one or more of the operands being true results in the statement being true. As used herein, the phrase “based on” as used in, for example, “A is based on B” indicates that B is a factor that determines A, but B is not necessarily the only factor that determines A. 
     According to some example embodiments, apparatuses, systems, and methods are provided for implementing a reconfigurable antenna. The reconfigurable antenna may be controllable, according to some example embodiments, to operate in a first communications mode that supports communications at a first wavelength (or frequency) and in a second communications mode that supports communications at a second wavelength (or frequency). The first wavelength may be associated with a frequency between about 6 GHz and 24 GHz (also referred to as centimeter-wave) and the second wavelength may be associated with a frequency between about 24 GHz and 100 GHz (also referred to as millimeter-wave). The control circuitry and radio components that support the operation of the reconfigurable antenna (e.g., beam steering circuitry, analog to digital/digital to analog converter circuitry, other radio circuitry, and the like) may also be controllable to support operation of the antenna in both the first communications mode and the second communications mode, without requiring separate components to support operation in each mode. According to some example embodiments, the reconfigurable antenna may be referred to as a ReconMilli antenna. 
     According to some example embodiments, an example apparatus in the form of a reconfigurable antenna may comprise a plurality of antenna patches that may be formed into an patch antenna array. Switches may be disposed between the antenna patches that are configured to selectively connect some or all antenna patches to each other to change the communications mode of the reconfigurable antenna. The switches may be collectively referred to as a switch array comprising switches disposed between the various antenna patches. For example, a first antenna patch may have one or more switches that electrically connect an edge of the first antenna patch to an edge on a second antenna patch, that is adjacent to the first antenna patch. In some instances, more than one switch (e.g., two, three, etc.) may electrically connect the edge of the first antenna patch to the edge of the second antenna patch. 
     The switches may be individually controllable by a respective electric control signal, provided by control circuitry, that causes the switches to transition between a non-conducting state (e.g., open or off) or a conducting state (e.g., closed or on) to effectively change the physical dimensions of the reconfigurable antenna formed by the plurality of patches and allow for different communications modes. The switches may be embodied as, for example, transistors, microelectromechanical systems (MEMS) switches, diodes, or the like. Via control of the switches by the control circuitry, the physical dimension of the antenna formed by the plurality of antenna patches can be changed to support communications at different wavelengths (e.g., a first wavelength and a second wavelength) based on the states of the switches. As mentioned above, according to some example embodiments, the wavelengths for communications may be on the order of millimeter-wave communications with the switches in, for example, a first communications mode and associated configuration (e.g., all switches in the non-conducting state) and on the order of centimeter-wave with the switches in a second communications mode and associated configuration (e.g., all switches in the conducting state). 
     As mentioned above, there continues to be a need for antenna technology to evolve, particularly to support higher speed communications. For example, next-generation mobile devices, e.g., 5th generation (5G) and beyond, may be required to have spectrum flexibility capabilities to support improved communications. In other words, communications devices may be required to have the ability to operate across a wide-range or at different portions of the radio frequency spectrum, for example, from centimeter-wave (cmWave; colloquially, micro-wave) to millimeter-wave (mmWave). In some instances, 5G radio specifications have standardized PHY/MAC (physical layer/media access control) protocols for dual operations on centimeter-wave and millimeter-wave. Accordingly, antenna solutions, such as those described herein, may support such requirements and also cope with blockages from the user&#39;s hand, body, and various environmental objects. To do so, according to some example embodiments, reliable millimeter-wave connectivity can leverage, for example, an antenna with multiple millimeter-wave phased-array antennas accompanied by a fast transition to centimeter-wave connectivity. 
     Such requirements, can bring new challenges with regard to the physical space available on small, handheld mobile devices. In this regard, one fundamental challenge of implementing such antenna solution is implementing the solution in consideration of the limited physical space available to mobile devices. While coordination between centimeter-wave and millimeter-wave connectivity is a challenge, doing so in consideration of the limited physical space requirements is yet another that continues to be elusive. To address these and other challenges, according to some example embodiments, a reconfigurable antenna is provided herein. The reconfigurable antenna may be tunable to different frequencies (e.g., centimeter-wave, millimeter-wave, or the like) using a singular antenna assembly that is reconfigurable to support operation at different wavelengths and associated frequencies. In this manner, according to some example embodiments, an antenna assembly can be implemented with improved spectrum flexibility, while using reduced physical space for application with mobile devices. 
     According to some example embodiments, as described herein, a reconfigurable antenna may be implemented in the context of a wireless communications device. An example communications device  100  that may comprise and be configured to implement a reconfigurable antenna is shown in  FIG. 1 . The communications device  100  may be any type of wireless communications device, such as, for example, a mobile terminal or user equipment (e.g., smart phone), or a base station or other stationary wireless communications device. The communications device  100  may include, among other components, control circuitry  101  and an antenna assembly  115 . The control circuitry  101  may include a memory  102 , a processor  103 , and a communications interface  104 . The communications interface  104  may comprise a radio  110  and an antenna configuration controller  104 . The antenna assembly  115  may include an antenna patch array  116  and a switch array  117 . 
     As further described below, the control circuitry  101 , and more specifically, the communications interface  104  may be configured to control the radio  110  and the antenna assembly  115  to transmit and receive wireless communications. In the regard, wireless communications links  150  or  151  may be established between the antenna assembly  115  and respective antennas of the communications devices  180  and  190 . The communications links  150  and  151  may involve wireless signals at different frequencies or wavelengths and may be associated with different configurations of the antenna assembly  115 . In this regard, the communication link  150  may be a centimeter-wave link and the communication link  151  may be a millimeter-wave link. 
     The control circuitry  101  may be configured to receive inputs and provide outputs in association with the various functionalities of the communications device  100 . In this regard, the control circuitry  101  may comprise, for example, a memory  102 , a processor  103 , a communications interface  104 . As components of the control circuitry  101 , the communication interface  104  may comprise the radio  110  and antenna configuration controller  105 . The control circuitry  101  may be operably coupled to other components of the communications device  100  or other components of a device that comprises the communications device  100 . 
     Further, according to some example embodiments, control circuitry  101  may be in operative communication with or embody, the memory  102 , the processor  103 , and the communications interface  104 . Through configuration and operation of the memory  102 , the processor  103 , and the communications interface  104 , the control circuitry  101  may be configurable to perform various operations as described herein. In this regard, the control circuitry  101  may be configured to perform communications interface control and monitoring, support communications overhead, and manage remote communications, according to some example embodiments. 
     In some embodiments, the control circuitry  101  may be embodied as a chip or chip set. In other words, the control circuitry  101  may comprise one or more physical packages (e.g., chips) including materials, components or wires on a structural assembly (e.g., a baseboard). The control circuitry  101  may be configured to receive inputs (e.g., via peripheral components), perform actions based on the inputs, and generate outputs (e.g., for provision to peripheral components). In an example embodiment, the control circuitry  101  may include one or more instances of a processor  103 , associated circuitry, and memory  102 . As such, the control circuitry  101  may be embodied as a circuit chip (e.g., an integrated circuit chip, such as a field programmable gate array (FPGA)) configured (e.g., with hardware, software or a combination of hardware and software) to perform operations described herein. 
     In an example embodiment, the memory  102  may include one or more non-transitory memory devices such as, for example, volatile or non-volatile memory that may be either fixed or removable. The memory  102  may be configured to store information, data, applications, instructions or the like for enabling, for example, the functionalities described herein. The memory  102  may operate to buffer instructions and data during operation of the control circuitry  101  to support higher-level functionalities, and may also be configured to store instructions for execution by the control circuitry  101  and data that has been captured via, for example, a user interface or sensors. According to some example embodiments, such data may be generated based on other data and stored or the data may be retrieved via the communications interface  104  and stored. 
     As mentioned above, the control circuitry  101  may be embodied in a number of different ways. For example, the control circuitry  101  may be embodied as various processing means such as one or more processors  103  that may be in the form of a microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA, or the like. In an example embodiment, the control circuitry  101  may be configured to execute instructions stored in the memory  102  or otherwise accessible to the control circuitry  101 . As such, whether configured by hardware or by a combination of hardware and software, the control circuitry  101  may represent an entity (e.g., physically embodied in circuitry—in the form of control circuitry  101 ) capable of performing operations according to example embodiments while configured accordingly. Thus, for example, when the control circuitry  101  is embodied as an ASIC, FPGA, or the like, the control circuitry  101  may be specifically configured hardware for conducting the operations described herein. Alternatively, as another example, when the control circuitry  101  is embodied as an executor of software instructions, the instructions may specifically configure the control circuitry  101  to perform the operations described herein. 
     The communication interface  104  may include one or more interface mechanisms for enabling communication by controlling the radio  110  to generate the communications links  150  and  151 . In some cases, the communication interface  104  may be any means such as a device or circuitry embodied in either hardware, or a combination of hardware and software that is configured to receive or transmit data from/to devices in communication with the control circuitry  101 . The communications interface  104  may support wireless communications via the radio  110  using various communications protocols (802.11WIFI, Bluetooth, cellular, WLAN, 3GPP NR or the like). Further, the communications interface  104  may be configured to conduct communications under 5G communications protocols including those that leverage centimeter-wave and millimeter-wave communications. 
     The antenna configuration controller  105  may be a component or module configured to control the configuration of the antenna assembly  115 , and more specifically, control the states of the switches of the switch array  117  as described herein. The antenna configuration controller  105  may be configured, according to some example embodiments, to individually control the switches of the switch array  117  via, for example, addressable pins, multiplexing, or the like. According to some example embodiments, the antenna patch array  116  of the antenna assembly  115  may comprise a plurality of antenna patches (e.g., patch elements) connected to each other via electrically controllable switches of the switch array  117 . In this regard, as mentioned above and described further below, the antenna configuration controller  105  may be configured to provide signals to control the switches of the switch array  117  to change the state of the switches and thereby the physical dimensions of an operating portion of the antenna patch array  116  to provide for operation of the antenna assembly  115  at different frequencies and wavelengths. The antenna assembly  115  may be driven by the radio  110  which may supply the signals to the antenna assembly  115  for wireless transmission or receive signals from the antenna assembly  115  for decoding and provision to the control circuitry  101 . 
     The radio  110  may be any type of physical radio comprising radio components. For example, the radio  110  may include components such as a power amplifier, mixer, local oscillator, modulator/demodulator, and the like. The components of the radio  110  may be configured to operate in a plurality of spectral bands. In this manner, the components of the radio  110  may be adaptable based on the configuration of the antenna assembly  115 . According to some example embodiments, the radio  110  may include amplitude and phase shift control circuitry that supports beam forming, MIMO precoding control circuitry, and ADC/DAC (analog to digital converter/digital to analog converter) that are configurable based on the communications mode and configuration of the antenna assembly  115 . As such, according to some example embodiments, dedicated radio circuitry for operation in each of the different antenna communications modes may not be required, and therefore a single radio and associated components may be configured or adjusted and utilized in response to changes in the communications mode of the antenna assembly  115 . Further, the radio  110  may be configured to receive signals from the control circuitry  101  for transmission to the antenna assembly  115 . In some example embodiments, the radio  110  may be a software defined radio. 
     The following provides a further description of example embodiments of the antenna assembly  115  and the manners in which the antenna assembly  115  may be controlled (e.g., via operation of the antenna configuration controller  105 ) to operate as a reconfigurable antenna. The antenna assembly  115  may be constructed and configured based on the principle that the operating frequency of an antenna is inversely proportional to the physical dimension of the antenna. As such, by changing the dimensions of the antenna dynamically, the frequency and wavelength at which the antenna operates can be controlled. For example, centimeter-wave antenna that is split into physically smaller pieces could operate as one or more millimeter-wave antennas. Similarly, if multiple antennas could be joined physically, then the multiple millimeter-wave antennas could be configured to act as a single centimeter-wave antenna. 
     The following describes some configurations of example antenna patch arrays (e.g., antenna patch array  116 ) that could be components of the antenna assembly  115  according to some example embodiments. Additionally, analysis of the operation of the antenna patch arrays in a given configuration is also described. According to some example embodiments, the antenna assembly  115  may comprise an N by N (or square) phased array  200  of antenna patches  210  as shown in  FIG. 2 . The antenna patches  210  may be sized to operate at, for example, 28 GHz when operated as a beam forming phased array. The antenna patches  210  may be organized in a grid, and the patches  210  may be, for example, square or rectangular in shape. Each patch  210  may be affixed to a planar substrate and may be formed of a conductor such as metal (e.g., aluminum). 
     As shown in  FIG. 3 , according to some example embodiments, an antenna assembly  300  (e.g., a portion of the antenna assembly  115 ) may include the antenna patch array  200  comprising antenna patches  210 . However, the antenna patches  210  may have switches  310  disposed between each edge of a patch  210  that has an adjacent patch  210  within the grid of patches  210 . The edge of the patch  210  may form a portion of the perimeter of the patch  210  at the outer extents of the patch  210 . The switches  310  are shown as connected to a mid-edge portion of the edge of the patches  210 , since the switches are not connected at or near the corners of the patches  210 . The switches  310  may be configured to connect (e.g., in a conducting state) the patches  210  to form a connected, larger antenna or disconnect (e.g., in a non-conducting state) the patches  210  to form one or more smaller antennas. The switches  310  may be controlled by, for example, the antenna configuration controller  105 . Although not shown in  FIG. 3 , each switch  310  may be a three-terminal device with two terminals being on either side of the switch and a third terminal that controls the state of the switch. 
     With reference to  FIG. 4 , an antenna assembly  400  is shown. The antenna assembly  400  may be comprised of a 3×3 phased array of antenna patches  410  (which may be the same or similar to the patches  210 ) on a substrate  440  (e.g., an epoxy glass substrate such as an FR4 substrate). The antenna patches  410  may therefore comprise an patch antenna array. According to some example embodiments, as shown in  FIG. 4 , the antenna patches  410  may be connected to each adjacent patch  410  at each edge by, for example, three switches  420  (only a few are labeled) indicated by the connected circles between the patches  410 . The three switches  420  (which may be the same or similar to the switch  310 ) may be arranged between two adjacent patches  410  to have a first switch  420  that connects between two edge corners of two patches  410 , a second switch that connects between two mid-edge portions of the two patches  410 , and a third switch that connects between the other two edge corners of the two patches  410 . Such a switch configuration may be implemented between edges of the patches  410  that are adjacent to the an edge of another patch  410 . As such, according to some example embodiments, thirty-six switches  420  may be employed between the various patches  410  of the 3×3 patch array. While three switches  420  are used in this example embodiment, it is understood that any number of switches may be disposed between the edges of the adjacent patches  410 . The switches  420  may form a switch array of the antenna assembly  400 . The phased array of patches  410  may be driven by an input/output port  430 , which may be connected to a radio (e.g., radio  110 ). The input/output port  430  may be electrically connected directly to one of the patches  410  (e.g., the bottom row, centrally located patch  410 ) and to the other patches  410  via the switches  420 . In this regard, a communications signal to be output by the antenna assembly  400  may be provided to the port  430  to be transmitted by the antenna assembly  400 , or a communications signal received by the antenna assembly  400  may be provided as an electrical signal at the port  430  to the radio. 
     Initially, for example, with the patches  410  operating as a phased array at 28 GHz, beamforming may be performed by controlling the signals to the patches  410  to steer the main beam direction by appropriate amplitude and phase-shift control. In this regard, according to some example embodiments, the radio may be separately connected to each patch  410  in the array to provide a separate signal for beam steering. The graphs  500  and  600  of  FIGS. 5 and 6 , respectively, show the beamwidth control of a phased array antenna (e.g., a millimeter-wave antenna) as the number of patches  410  in the array increases. 
     Analyses have been performed to show the performance of an example antenna assembly, according to some example embodiments, with all of the switches closed (i.e., all adjacent patches  410  are shorted together) and also with all of the switches open (i.e., all adjacent patches  410  are disconnected). The graph  700  of  FIG. 7  shows that the antenna assembly  400  resonates at, for example, the desired frequencies for millimeter-wave and centimeter-wave. In this regard, the graph  700  shows the frequency reconfigurability between 28.45 GHz to 6.9 GHz through measure of the return losses (Si′) with all switches  420  in the conducting/closed/on position/state and the non-conducting/open/off position/state. 
     The switches  420  may be formed in a number of different ways. High-frequency switching technologies, such as radio frequency microelectromechanical systems (RF MEMS), PIN (p-type intrinsic n-type material) diodes, field effect transistors (FETs), high electron mobility transistors (HEMTs), or the like. In this regard, PIN diodes can, for example, have excellent centimeter-wave performance, but may draw high current in the low-loss state. While FET switches may require very low control power, FET switches may suffer from relatively high insertion losses. RF MEMS switches, albeit with relatively low switch speed, may consume ultra-low power, and may have high switch performance with a high linear response. The fabrication of RF MEMS switches may also be relatively less expensive due to being developed in commercial foundries in the standard back-end-of-line process, enabling monolithic integration. According to some example embodiments, a MEMS switch may provide less than 10 microsecond switch time. As such, the use of RF MEMS switches may be preferred, according to some example embodiments, for the antenna assembly  115  of an example reconfigurable antenna. 
     An RF MEMS switch may be a micromechanical system with electronically controlled components that are sub-millimeter in size and may be electrostatically actuated. According to some example embodiments, an RF MEMS switch need not consume power to maintain a current state (e.g., conducting or non-conducting). According to some example embodiments, the RF MEMS switch may be a capacitive, fixed beam RF MEMS switch. The use of RF MEMS switches, according to some example embodiments, even with perfect isolation, may increase the physical dimension of individual antenna patches  410 , which may adversely affect the millimeter-wave operation. In this regard,  FIG. 8A  shows an antenna array  800  with a gap length  810  (GL) between the patches defined. As shown in the corresponding graph  850  of  FIG. 8B , smaller gap lengths yield poorer response because of the electromagnetic coupling between the patches. In consideration of switch widths  910  with switches in place between the patches of the array  900 , the effect of the different switch widths (GW) is shown in graph  950  of  FIG. 9B . Similarly,  FIG. 10A  shows an isolated single patch  1000  with switch width  1010  and the impact of different switch widths (GW) is shown in the graph  1050  of  FIG. 10B . 
     As such, according to some example embodiments, a larger switch width may change the millimeter-wave frequency response since the area of the antenna increases. However, a larger switch width can yield better performance at centimeter-wave (switches closed) since there are more substantial contacts. To minimize the effect of switch width and achieve effective performance, for example, at both millimeter-wave and centimeter-wave, multiple (e.g., three per edge) narrow switches may be used. In this regard, the isolated patch  1100  of  FIG. 11A  shows an implementation of multiple narrow switches  1110  (i.e. three switches on each edge adjacent another patch). The graph  1150  of  FIG. 11B  shows the improved return losses at the different switch widths (GW). In this regard, an array of patches  1200  with closed switches is shown  FIG. 12A , and a graph of the response at different switch widths (GW) is shown in graph  1250  of  FIG. 12B . Similarly, an array of patches  1300  with open switches is shown  FIG. 13A , and a graph of the response at different switch widths (GW) is shown in graph  1350  of  FIG. 13B . As such, these graphs  1250  and  1350  show that the antenna achieves improved return losses at, for example, both centimeter-wave and millimeter-wave with multiple narrow switches. 
     Additionally, because practical switches are not perfect isolators when open, a residual electromagnetic coupling can occur, even when the switches are not conducting or open (turned off), which may affect, for example, millimeter-wave beamforming performance. To understand the effect, the beam patterns may be measured with and without perfect isolation. In this regard, for example, a 60 dB isolation between the patches may be used to emulate beam patterns with approximately perfect switch isolation as shown in the graphs  1400  and  1450  in  FIGS. 14A and 14B , respectively. However, 30 dB isolation between patches may be used for the imperfect case. As such, graphs  1500  and  1550  in  FIGS. 15A and 15B , respectively, show the beam patterns for the imperfect case. As can be seen, gain variations between the perfect and imperfect cases are present on the beam pattern, but the differences are not significant. However, according to some example embodiments, a larger phased-array may suffer more from the imperfect isolation. Such imperfection may be overcome by appropriate codebook design for millimeter-wave phased array. 
     Compared to a traditional architecture with isolated centimeter-wave and millimeter-wave antennas, the underlying circuits and signal processing modules of a radio for the reconfigurable antenna, according to some example embodiments, may remain unchanged. In other words, according to some example embodiments, the reconfigurable antenna may operate in association with a circuitry that can support operation in more than one communications mode, without requiring dedicated circuitry for each mode. Rather, the circuitry may also be reconfigured for operation in the current communications mode (e.g., centimeter-wave mode or millimeter-wave mode) of the reconfigurable antenna. 
     For example, the amplitude and phase-shift circuit of, for example, the radio  110 , may control the analog beamforming, and the digital MIMO (multiple-input and multiple-output) precoding module of, for example, the radio  110 , may control the digital beamforming. Additionally, according to some example embodiments, the switch trigger logic of the antenna configuration controller  105  may multiplex the operations between millimeter-wave and centimeter wave modes. However, the reconfigurable antenna, according to some example embodiments, may support reuse of at least some of the signal processing modules (e.g., within and implemented by the control circuitry  101 ). For example, the MIMO precoder of the radio  110  may be reused for millimeter-wave hybrid beamforming to serve multiple users. Additionally, the amplitude and phase-shift circuit, of the radio  110 , may be reused for centimeter-wave mode operation to reduce the precoding complexity. Also, the ADC/DAC chain, of the radio  110 , can be reconfigured dynamically to adapt to MHz and GHz sampling for centimeter-wave and millimeter-wave modes, respectively. Thus, instead of duplicating the circuits and signal processing modules, a reconfigurable antenna, according to some example embodiments, may allow for integration of the circuits and processing modules for operation in either mode to reduce the cost and size, improve battery life, achieve better performance, and increase manufacturability. 
       FIG. 16  shows an example implementation of a reconfigurable antenna  1600  in a block-diagram, schematic form. The reconfigurable antenna  1600  may comprise components of a radio  1602  comprising analog amplitude and phase-shift control  1630 , DAC/ADC chain  1610 , and digital MIMO precoding module  1605 , each of which may be components of control circuitry  101  or the radio  110  of  FIG. 1 . The switching logic  1640  may an example of the antenna configuration controller  105 . Individual antenna patches (which may be individually sized for millimeter wave operation) in the antenna patch array  1650  may use amplitude and phase-shift control  1630  to steer an analog beam at  1660 . Triggered on the switching logic to place switches  1665  disposed between the patches in a conducting or short-circuit state thereby electrically connecting some or all of the antenna patches, may form one or more larger dimension antennas so that the frequency and wavelength of the reconfigurable antenna  1600  may be tuned to, for example, centimeter-wave mode or millimeter-wave mode. The reconfigurable antenna  1600  may achieve MIMO functionality at centimeter-wave through the digital precoding module  1605 . 
     Having described the structure and operation of example embodiments of the reconfigurable antenna provided herein, it is noted that many recent efforts in 5G have been addressing coordination issues between centimeter-wave and millimeter-wave connections and antennas. Software approaches may use centimeter-wave communication channel as a backup, redundant, or split path for millimeter-wave communication channel. As mentioned above, millimeter-wave connections can offer multiple gigabits per second wireless speed, but are susceptible to blockage, for example, in the context of mobility. Centimeter-wave connections may be relatively slow, but offer reliable connectivity. Thus, a combination of the two channels may be used for next-generation wireless and cellular standards and devices for both fast and reliable connectivity. The approach, according to some example embodiments, does not rely on separate hardware (including separate antennas) for the combined operations, and thus, has addressed a fundamental challenge of limited physical space on mobile devices. As such, the reconfigurable antenna, according to some example embodiments, can operate to achieve practical spectrum flexibility on limited physical space mobile devices. 
     Accordingly, an example embodiment of a reconfigurable antenna in the form of an apparatus (e.g., communications device  100 ) will now be described. In this regard, the apparatus may comprise an antenna assembly (e.g., antenna assembly  115 ), and the antenna assembly may comprise an antenna patch array (e.g., antenna patch array  116 ) comprising a plurality of antenna patches (e.g., patches  410 ). The apparatus may further comprise a switch array (e.g., switch array  117 ) comprising plurality of switches (e.g., switches  420 ). In this regard, each switch of the plurality switches may be electronically controllable to transition between states comprising a conducting state and a non-conducting state. Further, each switch may be electrically connected between two of the antenna patches of the antenna array. The apparatus may further comprise control circuitry (e.g., control circuitry  101 ) that is configured to control the states of the switches of the switch array to operate the antenna patch array in a first communications mode at a first wavelength, and control the states of the switches of the switch array to operate the antenna patch array in a second communications mode at a second wavelength. 
     According to some example embodiments, the antenna patches of the antenna patch array may be individually sized for millimeter-wave operation. Additionally, the first wavelength may be a millimeter-wave wavelength, and the second wavelength is a centimeter-wave wavelength. Additionally or alternatively, the antenna patch array may comprise a first antenna patch and a second antenna patch, and the switch array may comprise a first switch connected between the first antenna patch and the second antenna patch. The first switch may be controlled by the control circuitry to be in a non-conducting state in the first communications mode, and the first switch may be controlled by the control circuitry to be in a conducting state in the second communications mode. Additionally, according to some example embodiments, the switch array may further comprise a second switch and a third switch. The second switch may be connected between the first antenna patch and the second antenna patch. The third switch may be connected between the first antenna patch and the second antenna patch. According to some example embodiments, the second switch and the third switch may be controlled by the control circuitry to be in a non-conducting state in the first communications mode, and the second switch and the third switch may be controlled by the control circuitry to be in a conducting state in the second communications mode. Additionally, the antenna patch array may further comprise a third antenna patch, and the switch array may further comprise a fourth switch, a fifth switch, and a sixth switch. Each of the fourth switch, the fifth switch, and the sixth switch may be connected between the first antenna patch and the third antenna patch. The fourth switch, the fifth switch, and the sixth switch may be controlled by the control circuitry to be in a non-conducting state in the first communications mode, and the fourth switch, the fifth switch, and the sixth switch may be controlled by the control circuitry to be in a conducting state in the second communications mode. 
     Additionally or alternatively, according to some example embodiments the switches of the switch array may comprise radio frequency microelectromechanical systems (RF MEMS) switches, p-type intrinsic n-type (PIN) diodes, or field effect transistors (FETs). Additionally or alternatively, according to some example embodiments, each antenna patch of the antenna patch array may be connectable to two other antenna patches via the switch array. 
     Additionally or alternatively, according to some example embodiments, each antenna patch may comprise a rectangular shape and the antenna patch array may be arranged in a grid. The antenna patch array may comprise a first antenna patch and a second antenna patch. The switch array comprises a first switch, a second switch, and a third switch connected between the first antenna patch and the second antenna patch. The first switch may be connected between a first edge corner of the first antenna patch and a first edge corner of the second antenna patch. The second switch may be connected between a second edge corner of the first antenna patch and a second edge corner of the second antenna patch, and the third switch may be connected between a first mid-edge portion of the first antenna patch and a first mid-edge portion of the second antenna patch. According to some example embodiments, Additionally or alternatively, the antenna patch array may be an N by N array. Additionally or alternatively, the control circuitry may be further configured to perform analog and digital beamforming via the antenna patch array in both the first communications mode and the second communications mode. Additionally or alternatively, the control circuitry may comprise a digital to analog converter/analog to digital converter (DAC/ADC) that operates in both the first communications mode and the second communications mode. 
     Referring now to  FIG. 17 , a flowchart of an example method for configuring and controlling a reconfigurable antenna is provided. The example method may include, at  1700 , controlling, via control circuitry, states of switches of a switch array to operate an antenna patch array in a first communications mode at a first wavelength. In this regard, the antenna patch array may comprise a plurality of antenna patches and the switch array may comprise a plurality of switches. Each switch of the plurality switches may be electronically controllable by the control circuitry to transition between states comprising a conducting state and a non-conducting state. Each switch may be electrically connected between two of the antenna patches of the antenna array. According to some example embodiments, the example method may further comprise, at  1710 , controlling, via control circuitry, the states of the switches of the switch array to operate the antenna patch array in a second communications mode at a second wavelength. 
     Additionally, according to some example embodiments, the antenna patches of the antenna patch array may be individually sized for millimeter-wave operation. Further, the first wavelength may be a millimeter-wave wavelength, and the second wavelength may be a centimeter-wave wavelength. Additionally or alternatively, the antenna patch array may comprise a first antenna patch and a second antenna patch. The switch array may comprise a first switch connected between the first antenna patch and the second antenna patch. In this regard, the example method may further comprise controlling, by the control circuitry, the first switch to be in a non-conducting state in the first communications mode, and controlling, by the control circuitry, the first switch to be in a conducting state in the second communications mode. 
     Additionally, according to some example embodiments, the switch array may further comprise a second switch and a third switch. The second switch may be connected between the first antenna patch and the second antenna patch, and the third switch may be connected between the first antenna patch and the second antenna patch. Additionally or alternatively, the example method may comprise controlling, by the control circuitry, the second switch and the third switch to be in a non-conducting state in the first communications mode, and controlling, by the control circuitry, the second switch and the third switch to be in a conducting state in the second communications mode. Additionally or alternatively, the antenna patch array may further comprise a third antenna patch, and the switch array may further comprise a fourth switch, a fifth switch, and a sixth switch. Each of the fourth switch, the fifth switch, and the sixth switch may be connected between the first antenna patch and the third antenna patch. According to some example embodiments, the example method may further comprise controlling, by the control circuitry, the fourth switch, the fifth switch, and the sixth switch to be in a non-conducting state in the first communications mode, and controlling, by the control circuitry, the fourth switch, the fifth switch, and the sixth switch to be in a conducting state in the second communications mode. Additionally or alternatively, the switches of the switch array may comprise radio frequency microelectromechanical systems (RF MEMS) switches, p-type intrinsic n-type (PIN) diodes, or field effect transistors (FETs). Additionally or alternatively, according to some example embodiments, each antenna patch of the antenna patch array is connectable to two other antenna patches via the switch array. 
     Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe exemplary embodiments in the context of certain exemplary combinations of elements or functions, it should be appreciated that different combinations of elements or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. In cases where advantages, benefits or solutions to problems are described herein, it should be appreciated that such advantages, benefits or solutions may be applicable to some example embodiments, but not necessarily all example embodiments. Thus, any advantages, benefits or solutions described herein should not be thought of as being critical, required or essential to all embodiments or to that which is claimed herein. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.