Patent Publication Number: US-2020295467-A1

Title: Electromagnetic bandgap isolation systems and methods

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/819,418 filed Mar. 15, 2019 and entitled “ELECTROMAGNETIC BANDGAP ISOLATION SYSTEMS AND METHODS,” which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     BACKGROUND 
     Radar systems are commonly used to detect targets (e.g., objects, geographic features, or other types of targets), such as targets in proximity to watercraft, aircraft, vehicles, or fixed locations. The radar systems may transmit (e.g., broadcast) radar signals and receive return signals. Such return signals may be based on reflections of the transmitted radar signals by targets. 
     SUMMARY 
     Various electromagnetic bandgap (EBG) structures, radar systems incorporating EBG structures, and methods of manufacturing EBG structures and radar systems incorporating EBG structures are disclosed. For example, in certain embodiments, such a radar system incorporating an EBG structure may be implemented in a cost-efficient manner and with a high degree of functionality. 
     In one or more embodiments, an electromagnetic bandgap isolator device includes a base support having a curved surface. The electromagnetic bandgap isolator device further includes a metamaterial. The metamaterial includes a continuous curved layer in contact with the base support. The metamaterial is configured to absorb energy associated with a frequency range. 
     In one or more embodiments, for a method of manufacturing an electromagnetic bandgap isolator device, the method includes providing a metamaterial. The method further includes coupling the metamaterial to a curved surface of a base support such that the metamaterial conforms to the curved surface of the base support. 
     In one or more embodiments, a radar system includes an electromagnetic bandgap isolator device. The radar system further includes a transmitter configured to emit a signal. The signal includes a first portion and a second portion. The radar system further includes a receiver. The electromagnetic bandgap isolator device is disposed between the transmitter and the receiver. The electromagnetic bandgap isolator device is configured to absorb the second portion of the signal. 
     In one or more embodiments, for a method of manufacturing a radar system, the method includes providing a transmitter and a receiver. The method further includes disposing the electromagnetic bandgap isolator device between the transmitter and the receiver. 
     In one or more embodiments, for a method of using an electromagnetic bandgap isolator device, the method includes emitting a signal using a transmitter antenna. The signal includes a first portion and a second portion. The method further includes absorbing, using the electromagnetic bandgap isolator device, the second portion of the signal of the transmitter antenna to prevent coupling of the second portion into a receiver antenna. 
     In one or more embodiments, a method includes emitting, by a transmitter, a first signal. The first signal includes a first portion and a second portion. The method further includes receiving, by a receiver, a second signal that is based on a reflection of the first portion of the first signal by an object. The method further includes absorbing, by an electromagnetic bandgap isolator device, the second portion of the first signal emitted by the transmitter to prevent coupling of the second portion into the receiver. 
     The scope of the invention is defined by the claims, which are incorporated into this section by reference. A more complete understanding of embodiments of the invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a block diagram of an example radar system in accordance with one or more embodiments of the present disclosure. 
         FIG. 2  illustrates an example electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
         FIG. 3  illustrates a top sectional view of an example electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
         FIG. 4  illustrates a magnified view of the metamaterial of the electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
         FIG. 5  illustrates an example equivalent circuit of the metamaterial of  FIG. 4  in accordance with one or more embodiments of the present disclosure. 
         FIG. 6  illustrates an example radar system including an electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
         FIG. 7  illustrates a flow diagram of an example process for assembling an electromagnetic bandgap device in accordance with one or more embodiments of the present disclosure. 
         FIG. 8  illustrates a flow diagram of an example process for assembling a radar system including an electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
         FIG. 9  illustrates a flow diagram of an example of a process for using an electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
         FIG. 10  illustrates a flow diagram of an example of a process for using a radar system in accordance with one or more embodiments of the present disclosure. 
         FIGS. 11A-11C  illustrate various views of an example base support for an electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
         FIGS. 12A-12D  illustrate various views of an example end support for an electromagnetic bandgap isolator device in accordance with one or more embodiments of the present disclosure. 
     
    
    
     Embodiments of the present disclosure and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures. 
     DETAILED DESCRIPTION 
     The detailed description set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology can be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a thorough understanding of the subject technology. However, it will be clear and apparent to those skilled in the art that the subject technology is not limited to the specific details set forth herein and may be practiced using one or more embodiments. In one or more instances, structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject technology. One or more embodiments of the subject disclosure are illustrated by and/or described in connection with one or more figures and are set forth in the claims. 
     Various systems and methods are disclosed for providing isolation using EBG-based isolator devices (e.g., also referred to simply as EBG isolator devices). In some embodiments, an EBG isolator device may be disposed between transmitter elements and receiver elements to provide isolation between the transmitter elements and the receiver elements, such as in radar applications. 
     For instance, in frequency-modulated continuous-wave (FMCW) radar systems, as well as other radars systems, disposing of such an EBG isolator device may minimize or eliminate an amount of radio frequency (RF) energy emitted by a radar transmitter from coupling into a radar receiver. Prevention (e.g., minimization, elimination, mitigation, attenuation) of such coupling of RF energy into the radar receiver is generally associated with improved radar performance. In some cases, desired performances may be characterized in relation to antenna gain, side lobe characteristics, beam shape, isolation, and/or others. 
     The EBG isolator device provides an electromagnetic bandgap. In some embodiments, the EBG isolator device includes a layer of material having structures defined thereon, where such structures define the electromagnetic bandgap. The structures may be formed on the material and tailored to meet specifications, such as a desired frequency of stop band. In this regard, for a given EBG isolator device, the electromagnetic bandgap of the EBG isolator device is a frequency range (e.g., or equivalently a wavelength range or an energy range) in which components of an electromagnetic (EM) wave within this frequency range nominally no longer propagates in the EBG isolator device due to the structures of the EBG isolator device. An EM wave (if any) that propagates within the stop band is generally attenuated to a degree such that the EM wave is rendered negligible. Such an attenuated EM wave may be considered as no longer propagating in the EBG isolator device. 
     In an embodiment, a layer of material and the structures defined thereon together provide a metamaterial. In this regard, a metamaterial may be formed by providing a layer of material and forming, on the layer of material, structures associated with desired electromagnetic bandgap properties in an arrangement over a sufficiently large area or volume of the layer of material. In some aspects, the structures are periodically arranged on the layer of material to cause the metamaterial to exhibit a desired performance. The metamaterial may be created with desired effective dielectric properties and permittivity, such as to achieve a desired electromagnetic bandgap. In one case, a metamaterial may be created such that it matches the free space impedance of an incident wave. For example, the near field electromagnetic distribution of a transmit antenna can be determined (e.g., simulated, measured), and a metamaterial may be created such that a match impedance is seen by the near field on the metamaterial surface. In some cases, iterative design of the transmit antenna and the metamaterial may be performed to obtain desired performances regarding antenna gain, side lobe, beam shape, and isolation, among others. 
     In some aspects, the structures of the metamaterial may be artificial magnetic conductors (AMCs). AMCs are structures that can be used to create a boundary for an incident EM wave such that a well-controlled phase shift is generated at its interface with air. In this regard, utilization of AMCs facilitates control of a reflected wave amplitude and phase in order to effectuate a desired response. In some embodiments, the metamaterial may include a conductive layer, a substrate layer (e.g., dielectric layer) on the conductive layer, conductive patches on the substrate layer, and vias that extend between and are in contact with the conductive layer and the conductive patches. In these embodiments, each AMC of the metamaterial may include a conductive patch, a portion of the conductive layer, a via between the conductive patch and the portion of the conductive layer, and a portion of the substrate layer. In an aspect, such AMCs may be represented by equivalent LC circuits. The AMCs may be arranged (e.g., periodically arranged or aperiodically arranged) over an area or a volume. 
     For comparison, relative to an arranged array of AMCs, a continuous sheet/layer of metal creates a 180-degree phase shift relative to an incident EM wave, which may effectively cause a reflected EM wave to be of equal amplitude and opposite phase to the incident EM wave. In a case of a continuous sheet/layer of metal, the addition of the reflected and incident waves would cause destructive interference and, in turn, would cause performance issues for an associated application (e.g., radar application) if there is not proper control. As such, utilization of AMCs provides improved control of a reflected wave amplitude and phase relative to utilizing a continuous sheet/layer of metal. 
     In an embodiment, the EBG isolator device is provided with a three-dimensional aspect. In some embodiments, to provide the three-dimensional aspect, the EBG isolator device has a non-flat shape. As a non-limiting example, the EBG isolator device may have a circular dome shape to effectuate impedance matching. In other cases, impedance matching may be achieved using other shapes, such as hyperbolic, parabolic, and other non-flat shapes. In one embodiment, the EBG isolator device includes a base support having a curved surface and a metamaterial having a continuous, curved surface in contact with the base support. The continuous, curved surface may be formed of a continuous, curved conductive layer. 
     In some aspects, the three-dimensional aspect of the EBG isolator device may allow impedance matching of EM waves emitted by a transmitter on the EBG isolator device at angles of incidence of interest (e.g., all possible angles of incidence). In some cases, this three-dimensional aspect of the EBG isolator device may be determined with consideration to the near field EM pattern for a transmitter antenna such that the near field impedance will see a match load coming from the EBG isolator device. In an embodiment, the three-dimensional aspect of the EBG isolator device may allow matching of an incident EM wave angle impinging at 90 degrees to the metamaterial surface of the device. In some cases, such an incident EM wave may be considered or referred to as a parasitic or an undesired EM wave as discussed below. In an aspect, utilizing a metamaterial including AMC structures facilitates matching of the incident EM wave at angles of incidence such as 90 degrees, as AMC structures may be defined for EM waves with a 90-degree angle of incidence. In this regard, the EBG isolator device may effectively act as a match load impedance to surface current and incident EM waves (e.g., to prevent coupling between transmitter antennas and receiver antennas). 
     Thus, using various embodiments, EBG isolator devices may be provided to prevent coupling of energy between two devices. As an example, in some embodiments, disposing an EBG isolator device between the transmitter and the receiver may minimize or eliminate coupling of parasitic/undesired energy (e.g., originating from the transmitter) into the receiver, which, thereby, improves performance (e.g., radar performance). In some embodiments, to prevent transmitted energy from coupling into the receiver, the EBG isolator device may be utilized to absorb surface current, convert incident electromagnetic waves into surface current to thereby allow the EBG isolator device to absorb the energy, and/or scatter at least a part of the incident EM waves away from the receiver due to an overall shape of the EBG isolator device, such as provided by a curvature and structures (e.g., periodic structures) of the EBG isolator device. Physical characteristics of the EBG isolator device may be determined to effectuate a desired response (e.g., frequency response) to incident electromagnetic waves. By way of non-limiting example, physical characteristics may include a three-dimensional aspect (e.g., curvature) of the metamaterial and the associated base support, material composition of the layer of material, structures formed on the layer of material, and/or others. 
     In a radar application, the receiver may be intended to receive reflected EM waves originating from a main lobe of a transmitter antenna. In an embodiment, the transmitter antenna may transmit EM waves in its main lobe, an object in a scene may reflect these EM waves, and the receiver may be intended to receive the reflected EM waves. In relation to the transmitter antenna&#39;s radiation pattern, in addition to the main lobe, the transmitter antenna may emit energy (e.g., EM waves/radiation) in one or more side lobe signals. In some cases, the receiver may also be intended to receive reflected EM waves originating from the side lobe(s) of the transmitter antenna. In an aspect, the transmitter antenna may transmit EM waves in its side lobe(s), an object in the scene may reflect these EM waves, and the receiver may be intended to receive the reflected EM waves. In some cases, other signals may be considered, to the receiver, parasitic/undesired signals (e.g., energy). Parasitic/undesired energy received by the receiver may include energy emitted by the transmitter antenna in the side lobe(s). For example, the transmitter antenna side lobe(s) may transmit EM waves that are not reflected by an object in a scene, but instead are incidentally directed toward the receiver (e.g., through coupling of the transmit EM waves emitted by the transmitter antenna straight to the receiver antenna via a line of sight between the transmitter antenna and the receiver antenna). Such EM waves may be considered parasitic/undesired signals. 
     As such, a signal (e.g., EM waves/radiation) emitted by the transmitter antenna may include a main lobe signal and one or more side lobe signals. In one embodiment, the main lobe signal may be considered a first portion (e.g., also referred to as a first component) of the signal emitted by the transmitter antenna. In an aspect, the first portion of the signal may also include one or more side lobe signal(s). One or more of its side lobe signals may be considered a second portion (e.g., also referred to as a second component) of the signal emitted by the transmitter antenna. As an example, the main lobe signal and one or more side lobe signals may be considered a first portion of the signal while additional side lobe signals (e.g., those that directly couple from the transmitter antenna to the receiver antenna) may be considered a second portion of the signal. The second portion may be considered an undesired/parasitic signal of the receiver antenna. It is noted that the designation of a portion of a signal as being a first portion or a second portion is arbitrary and utilized for convenience to identify different portions of the signal. 
     Referring now to the drawings,  FIG. 1  illustrates a block diagram of a radar system  100  in accordance with one or more embodiments of the present disclosure. Variations in the arrangement and type of the components may be made without departing from the spirit or scope of the claims as set forth herein. Additional components, different components, and/or fewer components may be provided. In various embodiments, the radar system  100  may be configured for use on watercraft, aircraft, vehicles, fixed locations, or other environments, and may be used for various applications such as, for example, leisure navigation, commercial navigation, military navigation, other types of navigation, or other applications. In one aspect, the radar system  100  may be implemented as a relatively compact portable unit that may be conveniently installed by a user. 
     The radar system  100  includes a transmitter circuitry  105 , an EBG isolator  110 , a receiver circuitry  120 , a memory  125 , processors  130 , a display  135 , a machine-readable medium  140 , and other components  145 . The transmitter circuitry  105  includes one or more transmit (TX) antenna elements and appropriate circuitry to generate radar signals and provide such radar signals to the TX antenna elements, such that these radar signals can be transmitted by the TX antenna elements. Such transmitted radar signals are denoted as signals  150  of  FIG. 1 . The transmitter circuitry  105  may include a waveform generator that generates various waveforms to be utilized as radar signals. Such waveforms may include pulses of various lengths (e.g., different pulse widths), FMCW signals, and/or other waveforms appropriate for radar applications. FMCW signals may be implemented, for example, as rising, falling, or rising/falling frequency sweeps (e.g., upchirps, downchirps, or up/down chirps). In some cases, the waveforms may be beamformed waveforms. The transmitter circuitry  105  may include one or more power amplifiers that receive the radar signals from the waveform generator and drive the radar signals on the TX antenna element(s) of the transmitter circuitry  105 . In some cases, characteristics of the radar signals may be based at least in part from control signals received by the processors  130 . 
     The receiver circuitry  120  may include one or more receive (RX) antenna elements (e.g., phased array antennas) and circuitry to process radar signals received by the RX antenna elements. Such received radar signals are denoted as signals  155  of  FIG. 1 . The RX antenna elements can receive radar signals  155 , which may be reflections of the transmitted radar signals  150  from targets/objects. These received radar signals  155  may be referred to as return signals. The receiver circuitry  120  may include appropriate circuitry to process these return signals. The receiver circuitry  120  may include one or more low-noise amplifiers (LNAs) for amplifying the received radar signals  155 . The receiver circuitry  120  may include a demodulator to receive the radar signals  155  and convert the received radar signals  155  to baseband. In some cases, the demodulator may generate I signals and Q signals based on the received radar signals  155 . The circuitry may include filters (e.g., low-pass filters) to be applied to the radar signals (e.g., baseband radar signals). The receiver circuitry  120  may include an analog-to-digital (ADC) circuit to convert the received radar signals  155 , or filtered versions thereof, which are analog signals, to digital radar signals. The digital radar signals may be provided to the processors  130  for further processing to facilitate radar applications (e.g., target detection applications). 
     The EBG isolator  110  is disposed between the transmitter circuitry  105  and the receiver circuitry  120  of the radar system  100 . The EBG isolator  110  may be utilized to prevent an amount of radio frequency (RF) energy (e.g., bandlimited RF energy) emitted by the transmitter circuitry  105  (e.g., the TX antenna element(s)) from coupling into the receiver circuitry  120  (e.g., the RX antenna element(s)). For instance, the RF energy may be associated with the signals  150 . Radar performance is generally improved by minimizing the RF energy from the transmitter circuitry  105  that may couple into the receiver circuitry  120  of the EBG isolator  110 . Desired performances may be characterized in relation to antenna gain, side lobe characteristics, beam shape, isolation, and/or others. As further discussed below with regard to the additional figures, the EBG isolator  110  prevents an amount of transmitted RF energy from coupling to the receiver circuitry  120  by absorbing surface current, converting incident EM waves into surface current such that the EBG isolator  110  may absorb the RF energy, and/or scattering at least a part of the incident EM waves away from the receiver circuitry  120  (e.g., away from the RX antenna element(s)) due to an overall shape of the EBG isolator  110 . 
     In an embodiment, the EBG isolator  110  may effectively provide a match load impedance to both the surface current and incident EM wave associated with RF energy emitted by the transmitter circuitry  105 . In this regard, TX to RX coupling may be prevented (e.g., eliminated, reduced, mitigated, attenuated) relative to a case in which the EBG isolator  110  is not disposed between the transmitter circuitry  105  and the receiver circuitry  120 . Improved isolation (e.g., increased isolation) is generally associated with a higher radar range and higher accuracy. In an aspect, a three-dimensional aspect of the EBG isolator  110 , further discussed below with regard to  FIGS. 2 and 3 , permits impedance matching at all angles of incidence of transmitter circuitry&#39;s  105  emitted EM waves upon the EBG isolator  110 . In some cases, the three-dimensional shape of the EBG isolator  110  may be optimized according to a near field EM wave pattern of the transmitter circuitry  105  (e.g., the TX antenna elements) such that a near field impedance associated with these EM waves sees a matching load coming from the EBG isolator  110 . In an embodiment, the EBG isolator  110  has a non-flat shape. As a non-limiting example, the EBG isolator  110  may have a circular dome shape to effectuate impedance matching. In some cases, impedance matching may be achieved using other shapes, such as hyperbolic, parabolic, and other non-flat shapes. 
     The processors  130  may be implemented as any appropriate processing device (e.g., microcontroller, processor, application specific integrated circuit (ASIC), logic device, field-programmable gate array (FPGA), circuit, or other device) that may be used by the radar system  100  to execute appropriate instructions, such as non-transitory machine readable instructions (e.g., software) stored on the machine-readable medium  140  and loaded into the memory  125 . For example, on an RX side, the processors  130  may be configured to receive and process radar data received by the receiver circuitry  120 , store the radar data, processed radar data, and/or other data associated with the radar data in the memory  125 , and provide the radar data, processed radar data, and/or other data associated with the radar data for processing, storage, and/or display. In this example, outputs of the processors  130  may be, or may be derived into, representations of processed radar data that can be displayed by the display  135  for presentation to one or more users. On a TX side, the processors  130  may generate radar signals or associated signals to cause radar signals to be generated and fed to the transmitter circuitry  105 , such that these radar signals can be transmitted by the TX antenna element(s) of the transmitter circuitry  105   
     The memory  125  includes, in one embodiment, one or more memory devices configured to store data and information, including radar data. The memory  125  may include one or more various types of memory devices including volatile and non-volatile memory devices, such as random access memory (RAM), dynamic RAM (DRAM), static RAM (SRAM), non-volatile random-access memory (NVRAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically-erasable programmable read-only memory (EEPROM), flash memory, hard disk drive, and/or other types of memory. As discussed above, the processors  130  may be configured to execute software instructions stored in the memory  125  so as to perform method and process steps and/or operations. The processors  130  may be configured to store in the memory  125  data such as, by way of non-limiting example, filter coefficients, beamforming coefficients, and object/target detection data. 
     The display  135  may be used to present radar data, images, or information received or processed by the radar system  100 . In one embodiment, the display  135  may be a multifunction display with a touchscreen configured to receive user inputs to control the radar system  100 . 
     The radar system  100  may include various other components  145  that may be used to implement other features such as, for example, sensors, actuators, communications modules/nodes, other user controls, communication with other devices, additional and/or other user interface devices, and/or other components. In some embodiments, other components  145  may include a humidity sensor, a wind and/or water temperature sensor, a barometer, a visible spectrum camera, an infrared camera, and/or other sensors providing measurements and/or other sensor signals that can be displayed to a user and/or used by other devices of radar system  100  to provide operational control of the radar system  100 . For example, such sensor signals may be utilized to compensate for environmental conditions, such as wind speed and/or direction; swell speed, amplitude, and/or direction; and/or an object in a path (e.g., line of sight) of the radar system  100 . Imagers (e.g., visible spectrum camera, infrared camera) may be utilized to provide situational awareness of a scene, such as by providing image data associated with captured radar data. In some cases, sensor information can be used to correct for movement (e.g., changes in position and/or speed) associated with the radar system  100  between beam emissions to provide improved alignment of corresponding radar returns/samples, for example, and/or to generate imagery based on the measured orientations and/or positions of the radar system  100  assembly/antennas. In some cases, an external orientation and/or position sensor can be used alone or in combination with an integrated sensor or sensors. In some cases, alternatively or in addition to having sensors and/or other devices as part of the radar system  100 , the sensors and/or other devices may be collocated with the radar system  100 . Such sensors and/or other devices may provide data to the radar system  100  (e.g., via wired and/or wireless communication). 
     In some cases, the radar system  100  may include one or more visible spectrum cameras and/or one or more infrared cameras, such as to capture image data of a scene scanned by the radar system  100 . In one embodiment, the other components  145  includes a communication interface that may communicate with another device that may be implemented with some or all of the features of the radar system  100 . Such communication may be performed through appropriate wired or wireless signals (e.g., Wi-Fi™, Bluetooth™, or other standardized or proprietary wireless communication techniques). In one example, the radar system  100  may be located at a first position (e.g., on a bridge of a watercraft in one embodiment) and may communicate with a personal electronic device (e.g., a cell phone in one embodiment) located at a second position (e.g., co-located with a user on another location on the watercraft). In this regard, the user&#39;s personal electronic device may receive radar data and/or other information from the radar system  100 . As a result, a user may conveniently receive relevant information (e.g., radar images, alerts, or other information) even while not in proximity to the radar system  100 . 
       FIGS. 2 and 3  illustrate a perspective view and a side view, respectively, of an example EBG isolator  200  in accordance with one or more embodiments of the present disclosure. Not all of the depicted components may be required, however, and one or more embodiments may include additional components shown in the figures. Variations in the arrangement and type of the components may be made without departing from the spirit or scope of the claims as set forth herein. Additional components, different components, and/or fewer components may be provided. 
     As shown in  FIGS. 2 and 3 , the EBG isolator  200  includes end supports  205 A and  205 B, a metamaterial  210 , engagement elements  215 A and  215 B, grooves (e.g., a groove  220 ), and a base support  225 . To allow coupling between the end support  205 A and the base support  225 , engagement elements  215 A and  215 B may be provided through the end support  205 A and into a receiving interface of the base support  225 . Although the engagement elements  215 A and  215 B are shown as screws, other types of engagement elements such as adhesives, bumps and ridges, and/or generally any fastener are contemplated. The end support  205 A may include a lip  230  (e.g., edge, cap, lid, or other restraining interface) to assist in maintaining the metamaterial  210  in a fixed position. Not shown in  FIGS. 2 and 3  are engagement elements provided through the end support  205 B and into a receiving interface of the base support  225  at an opposing side from the end support  205 A. In an aspect, the end supports  205 A and  205 B and the base support  225  provides a supporting structure for fixedly holding the metamaterial  210 . The end supports  205 A and  205 B may be made of any material suitable for a desired application. For example, the end supports  205 A and  205 B may be made of any metal, metal alloy, plastic, a combination thereof, and/or other material appropriate for a desired application. In one case, the end supports  205 A and  205 B may be made of aluminum. 
     The metamaterial  210  includes multiple, periodic instances of unit cells. The metamaterial  210  provides a mesoscopic physical system, in which a behavior of the metamaterial  210  is a result of behavior at the unit cell level. Characteristics of the unit cells (e.g., sizes and shapes that define the unit cells, distance between adjacent unit cells, etc.) may be designed to yield prescribed electromagnetic properties. In an aspect, each unit cell may include one or more AMC structures. An example of a metamaterial and its unit cells are described below with respect to  FIGS. 4 and 5 . 
     The base support  225  has a curved surface on which the metamaterial  210  may attach to conform to the curvature of the base support  225 . For example, the metamaterial  210  may be glued or otherwise coupled to the base support  225 . In this regard, a three-dimensional aspect of the EBG isolator  200  is provided by bending the metamaterial  210  over the curvature of the base support  225 . The base support  225  may be made of any material suitable for a desired application. For example, the base support  225  may be made of any metal, metal alloy, plastic, a combination thereof, and/or other material appropriate for a desired application. In one case, the base support  225  may be made of aluminum. A distance from a bottom surface of the base support  225  to an apex of the base support  225  is denoted as H in  FIG. 3 . In one embodiment, in designing the base support  225  for a radar application, the distance H and other dimensions of the base support  225  may be appropriate for radiation patterns of a transmitter and a receiver, and to limit electromagnetic interference due to the EBG isolator  200  while preventing undesired signals emitted by the transmitter from coupling into the receiver. 
     The grooves, of which the groove  220  is labeled in  FIGS. 2 and 3 , are disposed along a length of the metamaterial  210  to facilitate bending of the metamaterial  210  to conform to the curvature of the base support  225 . In one embodiment, the grooves are disposed along a length of the metamaterial  210  such that the grooves are perpendicular or substantially perpendicular to a line(s) of sight between a transmitter antenna and a receiver antenna for a radar system (e.g., the radar system  100  of  FIG. 1 ). In some cases, the disposition of the grooves in the metamaterial  210  between the transmitter antenna and receiver antenna may effectively attenuate/prevent coupling of parasitic/undesired signals (e.g., EM waves) radiating from the transmitter antenna from reaching the receiver antenna. As shown in  FIGS. 2 and 3 , the grooves divide the metamaterial  210  into a plurality of portions (e.g., strips, panels) having a shared ground plane  235 . In one example, a distance between adjacent portions of the metamaterial  210  (one such distance is denoted as G in  FIG. 3 ) may be approximately 1 mm. The distance G may be referred to as a groove width, a gap width, or a spacing. In one example, a width of each of the plurality of portions (one such width of a portion is denoted as F in  FIG. 3 ) may be approximately 14 mm. To maintain continuity of the ground plane  235  for the metamaterial  210 , the groove depth is less than a thickness of the metamaterial  210 . In one example, the thickness of the metamaterial is around 3.25 mm, such that the groove depth is less than 3.25 mm in order to maintain continuity of the ground plane  235 . The continuity of the ground plane  235  provides a continuous portion/layer of the metamaterial  210  that is in contact with the base support  225 . The ground plane  235  is continuous to maintain the surface currents inside the metamaterial  210  and maintain periodicity of the metamaterial  210 , thus defining and facilitating effective operation of a band gap of the metamaterial  210 . The ground plane  235  may be made of conductive material suitable for an intended application. For example, the ground plane  235  may be made of copper, and may be plated with silver, gold, nickel, or other metals. Distances and dimensions discussed herein may be variable to suit an intended application. In some cases, energy absorbed by EBG isolator  200  may be appropriately grounded by way of one or more of the end supports  205 A-B, the base support  225 , and/or the ground plane  235 . 
     A surface of the EBG isolator  200  opposite of the curved surface may be flat to facilitate attaching the EBG isolator  200  to a radar surface of a radar system (e.g., the radar system  100 ). The flat surface of the EBG isolator  200  may be attached to the radar surface in between transmit circuitry (e.g., TX antenna element(s)) and receive circuitry (e.g., RX antenna element(s)). In an aspect, the surface opposite of the curved surface may have grooves, notches, latches, and/or other features to facilitate attachment of the EBG isolator  200  to a radar system. 
     In various embodiments, as shown in  FIGS. 2 and 3 , to provide improved isolation performance (e.g., relative to a case in which the EBG isolator  200  is not disposed), the metamaterial  210  is provided on and as a curved surface (e.g., non-flat surface) and with the ground plane  235  that is continuous. In some cases, a monotonicity of the curved surface of the metamaterial  210  allows matching of an incident wave impedance with a near field of transmitter circuitry (e.g., near field of TX antenna element(s)). The monotonicity of the curved surface of the metamaterial  210  is provided by the curved surface monotonically sloping downwards away from an apex of the base support  225 . Various dimensions and distances associated with the EBG isolator  200  are provided as appropriate to facilitate conformity to the base support  225  in order to provide a substantially continuous surface for incident EM waves and monotonicity of the EBG isolator  200 . In  FIGS. 2 and 3 , the semi-cylindrical structure of the metamaterial  210  may utilize a knife-edge effect toward incident EM waves from a TX antenna element(s) and, thereby, prevent radiating EM waves from reaching RX antenna element(s). Although the foregoing describes an embodiment in which a metamaterial has grooves disposed therein, in other embodiments, a metamaterial does not have grooves disposed therein. For example, a metamaterial may be formed of one or more materials that can conform (e.g., be bent, have appropriate flexibility, etc.) to a curvature of a base support without the grooves to facilitate the conformity. Dependent on a material system of a metamaterial, fewer, more, or no grooves may be disposed on the metamaterial. In one case, a metamaterial may have a substrate (e.g., formed of plastic material) that can be thermally formed to a desired shape, such as a curved shape that conforms to an associated base support. In this case, fewer or no grooves may be needed to conform the substrate to the base support. 
       FIGS. 4 and 5  illustrate a top view and a side view, respectively, of a respective portion of an example metamaterial in accordance with one or more embodiments of the present disclosure. The metamaterial includes unit cells, of which, unit cells  405  and  410  are labeled in  FIGS. 4 and 5 . In an embodiment, the metamaterial  210  may be implemented using the metamaterial shown in  FIGS. 4 and 5 . 
     A top view of a conductive path and a via of nine unit cells are shown in  FIG. 4 . In  FIG. 4 , the ellipses to the left, right, above, and below the unit cells (e.g., the unit cells  405  and  410 ) indicate that one or more additional unit cells or no unit cells are provided to the left, right, above, or below, respectively, the unit cells. Similarly, in  FIG. 5 , the ellipses to the left and right, respectively, of the unit cells  405  and  410  indicate that one or more additional unit cells or no unit cells are provided to the left and the right of the unit cells  405  and  410 . 
     As shown in  FIGS. 4 and 5 , each unit cell includes a conductive patch, a portion of a conductive layer  415 , a portion of a substrate layer  420 , and a via between the conductive patch and the portion of the conductive layer  415 . In an aspect, such a unit cell may be referred to as an AMC. In this regard, the conductive layer  415  provides a continuous conductive layer shared by the unit cells of the metamaterial. The conductive layer  415  may be referred to as a ground plane common to the unit cells of the metamaterial. For example, the unit cell  405  includes a conductive patch  425 , a via  430 , and a portion of the conductive layer  415 . The unit cell  410  includes a conductive patch  435 , a via  440 , and a portion of the conductive layer  415 . In an aspect, each unit cell may be referred to as providing one mushroom structure of the metamaterial. 
     The vias (e.g., the vias  430  and  440 ) extend through a thickness T along a z-direction of the substrate layer  420 . In this regard, a height of the via is provided by the thickness T of the substrate layer  420 . In one aspect, the vias are plated with metal (e.g., copper plated) and filled with epoxy. The substrate layer  420  is a layer of dielectric material. The substrate layer  420  may be a layer of FR4 material, Rogers Corporation® RO4350B™, Arlon DiClad880, and/or other dielectric material as appropriate for an intended application. In one example, the thickness T is approximately 3.25 mm. The vias may have a diameter of approximately 0.5 mm. A space S x  and a space S y  (e.g., also referred to as a gap) denote a distance along an x-direction and a y-direction, respectively, between adjacent conductive patches of the unit cells. A width W x  and a width W y  denotes a width along an x-direction and a y-direction, respectively, of each unit cell. Each patch has a dimension W x ×W y . A distance D x  and D y  (e.g., referred to as a pitch, a center-to-center distance, an on-center spacing, or a heart distance) denotes a distance along an x-direction and a y-direction, respectively, between adjacent vias. In  FIGS. 4 and 5 , each unit cell is associated with a square-shape (e.g., a square-shaped mushroom structure) in which W x =W y , S x =S y , and D x =D y . As an example, each conductive plate may be a square of dimensions 1 mm×1 mm (e.g., W x =W y =1 mm). The spacing S x =S y  may be approximately 0.25 mm. The distance D x =D y  may be approximately 1.25 mm. Other embodiments may utilize unit cells having a patch of a rectangular shape (e.g., W x ≠W y  and/or S x ≠S y ) or other shape (e.g., triangular, hexagonal, pentagonal, circular, elliptical, etc.) dependent on application (e.g., desired characteristics, manufacturing costs, etc.). The conductive layer  415 , conductive patches, and vias may be made of any conductive material suitable for an intended application. For example, the conductive layer  415 , conductive patches, and vias may be made of copper, and may be plated with silver, gold, nickel, or other metals. 
     A transmission response of the metamaterial depends upon the size of the conductive patches (e.g., mushroom patches) of the unit cells, diameter of the vias of the unit cells, and the gap between the unit cells.  FIG. 5  illustrates an equivalent circuit model for the unit cells  405  and  410  of the metamaterial. The metamaterial may be represented or characterized by equivalent LC circuits having a capacitance C and an inductance L. A frequency response, including a resonant frequency, associated with the metamaterial may be determined based on the capacitance C and the inductance L. The resonant frequency is a central frequency of the band gap provided by the metamaterial. In this regard, a resonance associated with the metamaterial defines a frequency range of a stop band of the metamaterial, where the stop band provides a frequency range over which surface impedance is high to block flow of surface current. As such, the unit cells act as frequency-selective electric filters to block surface current flowing across the metamaterial. The unit cells (e.g.,  405 ,  410 ) may have structural characteristics designed to facilitate applications (e.g., radar applications) in a desired frequency range/band, such as the X-band (e.g., approximately between 8 GHz and 12.0 GHz), other microwave frequencies, or other frequencies based on a desired application. Structural characteristics of the unit cells include a pitch between unit cells, size of conductive patch of each unit cell, and so forth. 
     With reference to the unit cells  405  and  410 , the capacitance C of the equivalent circuit is determined based on the spacing (e.g., S x , S y ) between adjacent conductive patches of the unit cells  405  and  410  and the patch width (e.g., W x , W y ) of the unit cells. The inductance L of the equivalent circuit is based on dimensions of the vias  430  and  440  (e.g., via height and diameter) and an effective electrical length (e.g., a length of a conductive path) between the vias  430  and  440 . More generally, each adjacent pair of unit cells of the metamaterial have an equivalent LC circuit. The capacitance C is determined based on the spacing (e.g., S x , S y ) between adjacent conductive patches of the unit cells and the patch width (e.g., W x , W y ) of the unit cells. The inductance L of the equivalent circuit is based on via height and diameter and an effective electrical length between unit cells. 
     It is noted that  FIGS. 2-5  illustrate non-limiting examples of metamaterials. For instance, in a different implementation of a metamaterial, the vias of each unit cell may be positioned off-center of the conductive patches. Other metamaterials having a different curvature and/or different structures (e.g., AMC structures) than those shown in  FIGS. 2-5  may be utilized as appropriate, such as to realize a desired response (e.g., frequency response). 
       FIG. 6  illustrates a radar system  600  in accordance with one or more embodiments of the present disclosure. In some embodiments, the radar system  600  may be, may include, or may be a part of the radar system  100   FIG. 1 . Not all of the depicted components may be required, however, and one or more embodiments may include additional components shown in the figures. Variations in the arrangement and type of the components may be made without departing from the spirit or scope of the claims as set forth herein. Additional components, different components, and/or fewer components may be provided. 
     As shown in  FIG. 6 , the radar system  600  includes an EBG isolator  610 , a TX antenna  605 , and a RX antenna  615 . In some embodiments, the EBG isolator  610  may be, may include, or may be a part of the EBG isolator  110  or  200  of  FIG. 1  or  FIGS. 2 and 3 , respectively. In some embodiments, the TX antenna  605  may be, may include, or may be a part of the transmitter circuitry  105  of  FIG. 1 . In some embodiments, the RX antenna  615  may be, may include, or may be a part of the receiver circuitry  120  of  FIG. 1 . In an aspect, the RX antenna  615  may be a phased-array antenna. The EBG isolator  610  is disposed between the TX antenna  605  and the RX antenna  615  to provide isolation (e.g., prevent coupling) between the TX antenna  605  and the RX antenna  615 . In this regard, the EBG isolator  610  prevents signals transmitted by the TX antenna  605  from coupling into the RX antenna  615 . 
       FIG. 7  illustrates a flow diagram of an example of a process  700  for manufacturing an EBG isolator in accordance with one or more embodiments of the present disclosure. For explanatory purposes, the process  700  is described herein with reference to various components of one or more of  FIGS. 2 and 3 ; however, the process  700  is not limited to various components of  FIGS. 2 and 3 . Note that one or more operations may be combined, omitted, and/or performed in a different order as desired. 
     At block  705 , a metamaterial having unit cells is provided. At block  710 , grooves are added to the provided metamaterial to obtain the metamaterial  210 . For example, the provided metamaterial may be grooved (e.g., cut) such that the provided metamaterial is separated into portions that share the continuous ground plane  235 , as shown by the metamaterial  210  in  FIGS. 2  and  3 . The metamaterial  210  may be referred to as a grooved metamaterial. At block  715 , the metamaterial  210  is attached to the base support  225 . In an aspect, the metamaterial  210  may be attached to a curved surface of the base support  225 . Attachment may be performed using one or more engagement elements, such as adhesives, screws, and/or generally any fastener. The grooves (e.g.,  220 ) of the metamaterial  210  may facilitate bending of the metamaterial  210  such that the metamaterial  210  conforms to the curved surface of the base support  225 . In this regard, by bending the metamaterial  210 , the ground plane  235  provides a continuous, curved conductive layer that is attached to the curved surface of the base support  225 . At block  720 , the end supports  205 A and  205 B are attached to the base support  225 . Attachment may be performed using one or more engagement elements, such as adhesives, screws, and/or generally any fastener. Lips (e.g.,  230 ) of the end supports  205 A and  205 B may assist in maintaining the metamaterial  210  in a fixed position. 
       FIG. 8  illustrates a flow diagram of an example of a process  800  for assembling an EBG isolator in a radar system in accordance with one or more embodiments of the present disclosure. For explanatory purposes, the process  800  is described herein with reference to various components of one or more of  FIG. 1 ; however, the process  800  is not limited to various components of  FIG. 1 . Note that one or more operations may be combined, omitted, and/or performed in a different order as desired. 
     At block  805 , a radar system is provided. In some cases, the radar system may be the radar system  100  (without the EBG isolator  110 ) of  FIG. 1 . At block  810 , the EBG isolator  110  is disposed (e.g., positioned, placed, attached) between a transmitter antenna and a receiver antenna of the radar system. The transmitter antenna may be, may include, or may be a part of the transmitter circuitry  105  of  FIG. 1 . The receiver antenna may be, may include, or may be a part of the receiver circuitry  120  of  FIG. 1 . 
       FIG. 9  illustrates a flow diagram of an example of a process  900  for using an EBG isolator in accordance with one or more embodiments of the present disclosure. For explanatory purposes, the process  900  is described herein with reference to various components of one or more of  FIG. 1 ; however, the process  900  is not limited to various components of  FIG. 1 . Note that one or more operations may be combined, omitted, and/or performed in a different order as desired. 
     At block  905 , a transmitter antenna emits a signal (e.g., containing RF energy). In some cases, the transmitter antenna may be, may include, or may be a part of the transmitter circuitry  105  of  FIG. 1 . At block  910 , an EBG isolator prevents a portion of the signal emitted by the transmitter antenna from coupling into a receiver antenna. For example, the EBG isolator may absorb the portion of the signal to prevent (e.g., eliminate, reduce, mitigate, attenuate) such coupling. The portion of the signal that is prevented from coupling into the receiver antenna may be considered as a parasitic/undesired signal to the receiver antenna. In an aspect, the signal emitted by the transmitter antenna includes a first component associated with a main lobe of the transmitter antenna, and one or more components associated with one or more side lobes of the transmitter antenna. The portion of the signal that is prevented from coupling into the receiver antenna by the EBG isolator may include some or all of the component(s) associated with the side lobe(s). In an aspect, the EBG isolator may prevent parasitic/undesired signals having various angles of incidence (e.g., including 90-degree angle of incidence) on the EBG isolator from coupling into (e.g., reaching) the receiver antenna. In some embodiments, the EBG isolator may be, may include, or may be a part of the EBG isolator  110  of  FIG. 1 . The receiver antenna may be, may include, or may be a part of the receiver circuitry  120  of  FIG. 1 . 
       FIG. 10  illustrates a flow diagram of an example of a process  1000  for using a radar system in accordance with one or more embodiments of the present disclosure. For explanatory purposes, the process  1000  is described herein with reference to various components of  FIG. 1 ; however, the process  1000  is not limited to various components of  FIG. 1 . Note that one or more operations may be combined, omitted, and/or performed in a different order as desired. 
     At block  1005 , a transmitter antenna emits a first signal. In some cases, the transmitter antenna may be, may include, or may be a part of the transmitter circuitry  105  of  FIG. 1 . At block  1010 , a receiver antenna receives a second signal associated with a reflection of a first portion of the first signal. For example, the second signal received by the receiver antenna may be a reflection, by an object, of the first portion of the first signal. In some cases, the receiver antenna may be, may include, or may be a part of the receiver circuitry  120  of  FIG. 1 . 
     At block  1015 , an EBG isolator prevents a second portion (e.g., parasitic/undesired portion) of the first signal emitted by the transmitter antenna from coupling into the receiver antenna. For example, the EBG isolator may absorb the portion of the signal to prevent (e.g., eliminate, mitigate, attenuate) such coupling. In an aspect, the first portion of the first signal includes a signal (e.g., energy) of a main lobe of the transmitter antenna, and the second portion of the first signal includes one or more signals corresponding to one or more side lobes of the transmitter antenna. In an aspect, the EBG isolator may prevent parasitic/undesired signals having various angles of incidence (e.g., including 90-degree angle of incidence) on the EBG isolator from coupling into (e.g., reaching) the receiver antenna. In some embodiments, the EBG isolator may be, may include, or may be a part of the EBG isolator  110  of  FIG. 1 . 
       FIGS. 11A-C  illustrate various views of an example base support  1100  for an EBG isolator device in accordance with one or more embodiments of the present disclosure. In some embodiments, the base support  1100  may be, may include, or may be a part of the base support  225  of  FIG. 3 . Not all of the depicted components may be required, however, and one or more embodiments may include additional components shown in the figures. Variations in the arrangement and type of the components may be made without departing from the spirit or scope of the claims as set forth herein. Additional components, different components, and/or fewer components may be provided. 
     As shown in  FIG. 11A , the base support  1100  includes receiving interfaces  1105 A and  1105 B to allow coupling between an end support (e.g., the end support  205 A of  FIG. 2 ) and the base support  1100 . The base support  1100  has a curved surface  1110  on which a metamaterial for the EBG isolator device may be glued or otherwise coupled to the base support  1100 . 
     As shown in  FIG. 11B , a base support side  1120  opposite of the curved surface  1110  may be substantially flat to facilitate attaching the EBG isolator device to a radar surface of a radar system. In one embodiment, the base support side  1120  has receptacles  1115 A-D embedded therein to facilitate attachment of the base support  1100  to the radar surface (e.g., via corresponding receiving interfaces of the radar surface) and/or provide support for additional circuitry and/or hardware of the radar system. 
     In one example, the base support  1100  may have a length (denoted as D 1  in  FIG. 11A ) of approximately between 300 mm and 400 mm. In one example, the base support  1100  may have a width (denoted as D 2  in  FIG. 11C ) of approximately 100 mm to 150 mm. In one example, the base support  1100  may have a height (denoted as D 3  in  FIG. 11C ) of approximately between 10 mm to 15 mm. It is noted that the dimensions of the base support  1100  may be varied to be suitable for an intended application. 
       FIGS. 12A and 12B  illustrate perspective views of an example end support  1200  for an EBG isolator device in accordance with one or more embodiments of the present disclosure.  FIGS. 12C and 12D  illustrate side views of the end support  1200  for the EBG isolator device in accordance with one or more embodiments of the present disclosure. In some embodiments, the end support  1100  may be, may include, or may be a part of end support  205 A or  205 B of  FIG. 2 . Not all of the depicted components may be required, however, and one or more embodiments may include additional components shown in the figures. Variations in the arrangement and type of the components may be made without departing from the spirit or scope of the claims as set forth herein. Additional components, different components, and/or fewer components may be provided. 
     As shown in  FIG. 12A-12D , the end support  1200  includes openings  1210 A and  1210 B, whereby engagement elements may pass through to a receiving interface of a base support (e.g., the base support  225  of  FIG. 3 ) to allow coupling between the end support  1200  and the base support. The end support has a lip  1205 , which may be, may include, or may be a part of lip  230  of  FIG. 2 . 
     In one example, the end support  1200  may have a length (denoted as D 4  in  FIG. 12B ) of approximately between 5 mm and 7.5 mm. In one example, the end support  1200  may have a width (denoted as D 5  in  FIG. 12D ) of approximately between 100 mm and 150 mm. In one embodiment, the end support  1200  may have a height (denoted as D 6  in  FIG. 12D ) of approximately between 15 mm and 20 mm. It is noted that dimensions of the end support  1200  may be varied to be suitable for an intended application. For instance, the dimensions of the base support  1100  and the end support  1200  (and associated dimensions of other components of the EBG isolator, such as a metamaterial) may be varied as appropriate to accommodate a transmitter-receiver pair and associated radiation patterns. 
     It is noted that dimensional aspects provided above are examples and that other values for the dimensions can be utilized in accordance with one or more implementations. Furthermore, the dimensional aspects provided above are generally nominal values. As would be appreciated by a person skilled in the art, each dimensional aspect has a tolerance associated with the dimensional aspect. Similarly, aspects related to distances between features provided above are also examples and also have associated tolerances. 
     Although the foregoing describes an EBG isolator primarily in the context of radar applications, in which the EBG isolator prevents coupling between a TX antenna and a RX antenna, the EBG isolator may be appropriately positioned between two devices (e.g., utilized for non-radar applications) to prevent coupling of signals emitted by one device from coupling into the other device. 
     Where applicable, various embodiments provided by the present disclosure can be implemented using hardware, software, or combinations of hardware and software. Also, where applicable, the various hardware components and/or software components set forth herein can be combined into composite components comprising software, hardware, and/or both without departing from the spirit of the present disclosure. Where applicable, the various hardware components and/or software components set forth herein can be separated into sub-components comprising software, hardware, or both without departing from the spirit of the present disclosure. In addition, where applicable, it is contemplated that software components can be implemented as hardware components, and vice versa. 
     Software in accordance with the present disclosure, such as non-transitory instructions, program code, and/or data, can be stored on one or more non-transitory machine-readable mediums. It is also contemplated that software identified herein can be implemented using one or more general purpose or specific purpose computers and/or computer systems, networked and/or otherwise. Where applicable, the ordering of various steps described herein can be changed, combined into composite steps, and/or separated into sub-steps to provide features described herein. 
     The foregoing description is not intended to limit the present disclosure to the precise forms or particular fields of use disclosed. Embodiments described above illustrate but do not limit the invention. It is contemplated that various alternate embodiments and/or modifications to the present invention, whether explicitly described or implied herein, are possible in light of the disclosure. Accordingly, the scope of the invention is defined only by the following claims.