Antenna aperture having antenna elements with electrostatic capacitors

Abstract

An antenna having a radio frequency (RF) radiating antenna element with a static capacitor is described. In some embodiments, the antenna includes an RF signal source and a plurality of radio frequency (RF) radiating antenna elements coupled to the RF signal source, each of the RF radiating antenna elements comprising a slot, a tuning element coupled to the RF signal source for tuning the slot as part of the RF radiating antenna element that generates a beam, and a fixed capacitor coupled to the RF signal source and coupled in series with the tuning element across the slot, the fixed capacitor for mitigating harmonic generation to control the linear response of the plurality of radio frequency (RF) radiating antenna elements.

Description

[Technical Field]

[0001] (Related Applications) This application claims priority to U.S. Patent Application No. 18 / 587,794, filed February 26, 2024, and is related to and claims the benefit of priority to U.S. Provisional Application No. 63 / 448,875, filed February 28, 2023, the disclosure of which is incorporated herein in its entirety.

[0002] (Technical field) Embodiments of the present disclosure relate to wireless communications, and more particularly, embodiments disclosed herein relate to antennas (e.g., metasurface antennas, phased array antennas, etc.) that include fixed capacitors coupled to varactors used to tune radio frequency (RF) radiating antenna elements. [Background technology]

[0003] Currently, there are several electronically steerable antennas. Electronically steerable antennas generate beams that can be electronically steered in different directions without physically moving the antenna. These antennas contain multiple RF radiating antenna elements that are controlled to generate a beam. One type of antenna is the phased array antenna. Phased array antennas use phase shifters to electronically vary the phase or signal delay, thereby steering the beam in different directions.

[0004] Metasurface antennas have recently emerged as another example of electronically steerable antennas that generate steered directional beams from lightweight, low-cost, planar physical platforms. Such metasurface antennas have recently been used in several applications, such as satellite communications.

[0005] Metasurface antennas can comprise metamaterial antenna elements that can selectively couple energy from a feed wave to generate a beam that can be controlled for use in communications. These antennas can achieve performance comparable to phased array antennas from an inexpensive and easy-to-manufacture hardware platform.

[0006] In some electronically steerable antennas, the radiating antenna elements include tuning elements to control their operation. These tuning elements may be non-linear devices that tune the antenna elements as part of the process of generating a beam with the antenna elements. Summary of the Invention

[0007] An antenna having a radio frequency (RF) radiating antenna element with a static capacitor is described. In some embodiments, the antenna comprises an RF signal source and a plurality of radio frequency (RF) radiating antenna elements coupled to the RF signal source, each of the RF radiating antenna elements including a slot, a tuning element coupled to the RF signal source for tuning the slot as part of the RF radiating antenna element that generates a beam, and a fixed capacitor coupled to the RF signal source and coupled in series with the tuning element across the slot, the fixed capacitor mitigating harmonic generation to control the linear response of the plurality of radio frequency (RF) radiating antenna elements.

[0008] Embodiments of the present invention and their advantages can be best understood by referring to the following description taken in conjunction with the accompanying drawings, which are not intended to limit in any way the changes in form and detail that may be made to the embodiments by those skilled in the art without departing from the spirit and scope of the embodiments of the present invention. [Brief explanation of the drawings]

[0009] [Figure 1] 1A-1C are exploded views of some embodiments of flat panel antennas.

[0010] [Figure 2] FIG. 1 illustrates an example of a communication system including one or more antennas according to some embodiments.

[0011] [Figure 3] FIG. 2 illustrates a capacitance-voltage (CV) curve of a varactor diode according to some embodiments.

[0012] [Figure 4] 1A-1C illustrate some embodiments of RF radiating antenna elements with varactors and MIM capacitors placed over each slot (iris).

[0013] [Figure 5] FIG. 10 is a graph showing the RF signal source voltage experienced by the varactor and MIM in the OFF mode of the TX element.

[0014] [Figure 6] 10 is a graph showing the RF signal source voltage received by the varactor and the MIM in the ON mode of the RX element.

[0015] [Figure 7] FIG. 10 is a flow diagram of some embodiments of a process for communicating with a metasurface antenna.

[0016] [Figure 8] 1A-1C illustrate some embodiments of a load-line phase shifter for a phased array antenna. DETAILED DESCRIPTION OF THE INVENTION

[0017] In the following description, numerous details are set forth to provide a more thorough explanation of embodiments of the present disclosure. However, it will be apparent to those skilled in the art that the teachings disclosed herein may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present disclosure.

[0018] Embodiments described herein include antennas having radio frequency (RF) radiating antenna elements, each including a fixed capacitor, such as, for example, a metal-insulator-metal (MIM) capacitor. In some embodiments, the fixed capacitor (e.g., MIM capacitor) operates in conjunction with a tuning element (e.g., a varactor) to control the RF radiating antenna element. In some embodiments, the antenna is part of a satellite user terminal. In some embodiments, the antenna is a metamaterial antenna having RF radiating antenna elements, for example, as described below. In some other embodiments, the antenna is a phased array antenna having RF radiating antenna elements. The teachings herein are not limited to metasurface antennas or phased array antennas, but may also be applied to other types of antennas.

[0019] The following disclosure will begin with an illustrative example of the technology related to the role of MIM capacitors in antennas such as metasurface antennas, followed by a description of example antenna embodiments, including the effect of high input RF power of an RF signal source on such antennas, including the effect of transmit (TX) input power on the TX radiating element and TX power on the receive (RX) radiating element.

[0020] (Antenna embodiment example) The techniques described herein can be used with various satellite antennas, such as flat panel satellite antennas. Several embodiments of such flat panel antennas are disclosed herein. In some embodiments, the flat panel satellite antenna is part of a satellite terminal. The flat panel antenna includes one or more arrays of antenna elements over an antenna aperture.

[0021] In some embodiments, the antenna aperture is a metasurface antenna aperture, such as the antenna apertures described below. In some embodiments, the antenna element comprises a radio frequency (RF) radiating antenna element. In some embodiments, the antenna element includes a tunable device for tuning the antenna element. Examples of such tunable devices include diodes and varactors, such as those described in U.S. Patent No. 11,489,266, entitled "Metasurface Antennas Manufactured with Mass Transfer Technologies," issued November 1, 2022. In some other embodiments, the antenna element comprises a liquid crystal (LC)-based antenna element, such as those disclosed in U.S. Patent No. 9,887,456, entitled "Dynamic Polarization and Coupling Control from a Steerable Cylindrically Fed Holographic Antenna," issued February 6, 2018, or other RF radiating antenna elements. It should be understood that other tuning devices, such as, but not limited to, tuning capacitors, tuning capacitance dies, package dies, microelectromechanical systems (MEMS) devices, or other tuning capacitance devices, can be placed in the antenna aperture or elsewhere in variations on the embodiments described herein.

[0022] While embodiments in the present disclosure can derive some examples in communications, some embodiments can be implemented in a variety of receiving, transmitting, and / or sensing or other similar applications, including, but not limited to, devices for sensing devices such as radar, lidar, sensors, and those in autonomous vehicle applications, as well as any other uses that can utilize the attributes of active metasurfaces according to various disclosed and undisclosed embodiments of the present disclosure.

[0023] In some embodiments, an antenna aperture having one or more arrays of antenna elements is composed of multiple segments coupled together. In some embodiments, when coupled together, the combination of segments forms a group of antenna elements (e.g., a closed ring of antenna elements concentric about the antenna feed). For more information on antenna segments, see U.S. Patent No. 9,887,455, entitled "Aperture Segmentation of a Cylindrical Feed Antenna," issued February 6, 2018.

[0024] 1 shows an exploded view of some embodiments of a flat panel antenna. Referring to FIG. 1, the antenna 100 includes a radome 101, a core antenna 102, an antenna support plate 103, an antenna control unit (ACU) 104, a power supply unit 105, a terminal housing platform 106, a COMM (communications) module 107, and an RF chain 108.

[0025] The radome 101 is the top of the enclosure that encloses the core antenna 102. In some embodiments, the radome 101 is constructed of a material that is weatherproof and transparent to radio waves to allow the beam generated by the core antenna 102 to extend outside the radome 101.

[0026] In some embodiments, the core antenna 102 comprises an aperture having RF radiating antenna elements. These antenna elements function as radiators (or slot radiators). In some embodiments, the antenna elements comprise scattering metamaterial antenna elements. In some embodiments, the antenna elements comprise both receive (Rx) and transmit (Tx) irises or slots interleaved and distributed across the surface of the antenna aperture of the core antenna 102. Such Rx and Tx irises can be grouped into two or more sets, each set for a separate, simultaneously controlled band. An example of an antenna element with such irises is described in U.S. Patent No. 10,892,553, entitled "Broad Tunable Bandwidth Radial Line Slot Antenna," issued January 12, 2021.

[0027] In some embodiments, the antenna elements comprise an iris (iris opening), and the antenna aperture is used to generate a shaped main beam using excitation from a cylindrical feed to radiate the iris opening via a tunable element (e.g., diode, varactor, patch, etc.). In some embodiments, the antenna elements can be excited to radiate a horizontally polarized field or a vertically polarized field at a desired scan angle.

[0028] In some embodiments, a tunable element (e.g., a diode, varactor, patch, etc.) is placed over each iris slot. The amount of radiated power from each antenna element is controlled by applying a voltage to the tunable element using a controller in the ACU 104. Traces to each tunable element in the core antenna 102 are used to supply a voltage to the tunable element. This voltage tunes or detunes the capacitance and therefore the resonant frequency of the individual element, resulting in beamforming. The required voltage depends on the tunable element used. Taking advantage of this property, in some embodiments, the tunable element (e.g., a diode, varactor, LC, etc.) integrates an on / off switch for energy transfer from the feed wave to the antenna element. When the switch is turned on, the antenna element radiates electromagnetic waves like an electrically small dipole antenna. Note that the teachings herein are not limited to having unit cells that operate in a binary manner for energy transfer. For example, in some embodiments where varactors are the tunable elements, there are 32 tuning levels. As another example, in some embodiments where LC is the tunable element, there are 16 tuning levels.

[0029] To tune an antenna element (e.g., a tunable resonator element / slot), the voltage between the tunable element and the slot can be modulated. Adjusting the voltage changes the capacitance of the slot (e.g., a tunable resonator / slot). Therefore, changing the capacitance can change the reactance of the slot (e.g., a tunable resonator / slot). The resonant frequency of the slot also changes according to the following equation: TIFF2026507133000002.tif10150where f is the resonant frequency of the slot, L and C are the inductance and capacitance of the slot, respectively. The resonant frequency of the slot affects the energy coupled to the antenna element from the feed wave propagating through the waveguide.

[0030] In particular, the generation of focused beams by metamaterial arrays of antenna elements can be explained by the phenomena of constructive and destructive interference, which are well known in the art. Individual electromagnetic waves add up to form a beam (constructive interference) if they have the same phase when they meet in free space, and cancel each other out (destructive interference) if they have opposite phases when they meet in free space. If the slots in the core antenna 102 are arranged so that each successive slot is located at a different distance from the excitation point of the feed wave, the scattered wave from that antenna element will have a different phase than the scattered wave from the previous slot. In some embodiments, if the slots are spaced a quarter of a wavelength apart, each slot will scatter a wave that has a quarter phase delay from the previous slot. In some embodiments, by controlling which antenna elements are turned on or off (i.e., by changing the pattern of which antenna elements are turned on and which are turned off) or which tuning levels are used, different constructive and destructive interference patterns can be generated and the antenna can change its beam direction.

[0031] In some embodiments, the core antenna 102 includes a coaxial feed used to provide a cylindrical wave feed via an input feed, such as described in U.S. Patent No. 9,887,456, issued February 6, 2018, entitled "Dynamic Polarization and Coupling Control from a Steerable Cylindrically Fed Holographic Antenna," or U.S. Patent No. 11,489,266, issued November 1, 2022, entitled "Metasurface Antennas Manufactured with Mass Transfer Technologies." In some embodiments, the cylindrical wave feed feeds the core antenna 102 from a central point with excitation propagating cylindrically outward from the feed point. In other words, the cylindrical feed wave is an outward-traveling concentric feed wave. Nevertheless, the shape of the cylindrical feed antenna around the cylindrical feed can be circular, square, or any shape. In some other embodiments, a cylindrically fed antenna aperture generates an inward-traveling feed wave. In such cases, the feed wave most naturally comes from a circular structure.

[0032] In some embodiments, the core antenna comprises multiple layers. These layers include one or more substrate layers that form the RF radiating antenna element. In some embodiments, these layers may also include impedance matching layers (e.g., wide angle impedance matching (WAIM) layers, etc.), one or more spacer layers, and / or dielectric layers. Such layers are well known in the art.

[0033] The antenna support plate 103 is coupled to the core antenna 102 and provides support for the core antenna 102. In some embodiments, the antenna support plate 103 includes one or more waveguides and one or more antenna feeds to provide the core antenna 102 with one or more feeds that are used by the antenna elements of the core antenna 102 to generate one or more beams.

[0034] ACU 104 is coupled to antenna support plate 103 and provides controls for antenna 100. In some embodiments, these controls include controls for the drive electronics for antenna 100 and matrix drive circuitry for controlling switching arrays scattered throughout the array of RF radiating antenna elements. In some embodiments, the matrix drive circuitry drives each antenna element individually from the other antenna elements using a unique address for applying voltages to the tunable elements of the antenna element. In some embodiments, the drive electronics of ACU 104 comprise commercially available LCD controllers used in commercial television equipment that adjust the voltages to each antenna element.

[0035] More specifically, in some embodiments, the ACU 104 provides an array of voltage signals to the tunable elements of the antenna element to create a modulation, or control, pattern. The control pattern tunes the elements to different states. In some embodiments, the ACU 104 uses the control pattern to control which antenna elements are turned on or off (or which tuning levels are used) and at which phase and amplitude levels at the operating frequency. Elements are selectively detuned for frequency operation by applying voltages. In some embodiments, multi-state control is used, where different elements are turned on and off to different levels, to more closely approximate a sinusoidal control pattern as opposed to a square wave (i.e., a sinusoidal gray-shade modulation pattern).

[0036] In some embodiments, ACU 104 also includes one or more processors that execute software to perform some of the control operations. ACU 104 may control one or more sensors (e.g., a GPS receiver, a three-axis compass, a three-axis accelerometer, a three-axis gyro, a three-axis magnetometer, etc.) to provide position and orientation information to the processor. The position and orientation information may be provided to the processor by other systems in the earth station and / or may not be part of the antenna system.

[0037] Antenna 100 also includes a COMM (communications) module 107 and an RF chain 108. Communications module 107 includes one or more modems that enable antenna 100 to communicate with various satellite and / or cellular systems, as well as a router that selects the appropriate network route based on metrics (e.g., Quality of Service (QoS) metrics, e.g., signal strength, delay, etc.). RF chain 108 converts analog RF signals to digital form. In some embodiments, RF chain 108 comprises electronic components that may include amplifiers, filters, mixers, attenuators, and detectors.

[0038] The antenna 100 also includes a power supply unit 105 for providing power to the various subsystems or components of the antenna 100 .

[0039] Antenna 100 also includes a terminal housing platform 106 that forms the bottom housing of antenna 100. In some embodiments, terminal housing platform 106 comprises multiple components that are coupled to other components of antenna 100, including radome 101, to enclose core antenna 102.

[0040] FIG. 2 illustrates an example of a communication system including one or more antennas described herein. Referring to FIG. 2, vehicle 200 includes antenna 201. In some embodiments, antenna 201 comprises antenna 100 of FIG. 1. In some embodiments, vehicle 200 may comprise any one of a number of vehicles, such as, but not limited to, an automobile (e.g., car, truck, bus, etc.), a marine vehicle (e.g., boat, ship, etc.), or an aircraft (e.g., crew jet, military jet, light craft, etc.). Antenna 201 may be used for communication while vehicle 200 is either stationary or moving. Antenna 201 may be used to communicate to a fixed location, for example, a remote industrial site (mining, oil, gas) and / or a remote renewable energy site (solar farm, wind farm, etc.).

[0041] In some embodiments, antenna 201 can be in communication with one or more communication infrastructures (e.g., satellite, cellular, network (e.g., the Internet), etc.). For example, in some embodiments, antenna 201 can be in communication with satellites 220 (e.g., GEO satellites) and 221 (e.g., LEO satellites), a cellular network 230 (e.g., LTE, etc.), and a network infrastructure (e.g., edge routers, the Internet, etc.). For example, in some embodiments, antenna 201 includes one or more satellite modems (e.g., GEO modems, LEO modems, etc.) to enable communication with various satellites, such as satellite 220 (e.g., GEO satellites) and satellite 221 (e.g., LEO satellites), and one or more cellular modems to communicate with cellular network 230. For another example of an antenna in communication with one or more communication infrastructures, see U.S. Patent No. 11,818,606, entitled "Multiple Aspects of Communication in a Diverse Communication Network," and issued November 14, 2023.

[0042] In some embodiments, antenna 201 performs dynamic beam steering to facilitate communication with various satellites. In such cases, antenna 201 can dynamically change the direction of the beam it generates to facilitate communication with different satellites. In some embodiments, antenna 201 includes multi-beam beam steering, which allows antenna 201 to simultaneously generate two or more beams, thereby allowing antenna 201 to simultaneously communicate with two or more satellites. Such functionality is often used when switching between satellites (e.g., performing a handover). For example, in some embodiments, antenna 201 generates and uses a first beam for communication with satellite 220 and simultaneously generates a second beam for establishing communication with satellite 221. After establishing communication with satellite 221, antenna 201 stops generating the first beam to terminate communication with satellite 220 and simultaneously switches to communication with satellite 221 using the second beam. For more information on multi-beam communications, please refer to U.S. Patent No. 11,063,661, entitled "Beam Splitting Hand Off Systems Architecture," issued on July 13, 2021.

[0043] In some embodiments, antenna 201 uses path diversity to allow a communication session occurring over one communication path (e.g., satellite, cellular, etc.) to continue during and after a handover to another communication path (e.g., another satellite, another cellular system, etc.). For example, if antenna 201 is in communication with satellite 220 and switches to satellite 221 by dynamically changing its beam direction, the session with satellite 220 will be combined with the session occurring between satellite 221.

[0044] Thus, the antennas described herein can be part of a satellite terminal enabling ubiquitous communications and multiple different communication connections. In some embodiments, the antenna 201 comprises a metasurface RF antenna having multiple RF radiating antenna elements tuned to a desired frequency using RF antenna element drive circuitry. The drive circuitry can include drive transistors (e.g., thin film transistors (TFTs) (e.g., CMOS, NMOS, etc.), low-temperature or high-temperature polysilicon transistors, memristors, etc.), microelectromechanical systems (MEMS) circuits, or other circuits for driving voltages to the RF radiating antenna elements. In some embodiments, the drive circuitry comprises an active matrix driver. In some embodiments, the frequency of each antenna element is controlled by an applied voltage. In some embodiments, this applied voltage is also stored in each antenna element (pixel circuit) until the next voltage write cycle.

[0045] Fixed-Capacitor-Based Compensation for Nonlinear Harmonic Generation in Antennas The embodiments described herein are devices and methods for compensating for known problems with nonlinear harmonic generation and self-tuning when using tuning elements, such as, but not limited to, varactor diodes in radio frequency (RF) circuits in antennas, such as those described above. In some embodiments, the device includes a fixed capacitor, such as a metal-insulator-metal (MIM) fixed capacitor, in series with the varactor diode. In some embodiments, the antenna includes a capacitor with an RF-radiating antenna element, each of the RF-radiating antenna elements including a slot, a tuning element that tunes the slot as part of the RF-radiating antenna element that generates the beam, and a fixed capacitor (e.g., an MIM capacitor) coupled in series with the tuning element across the slot. In some embodiments, the tuning element and fixed capacitor are within an integrated circuit (IC) die. The fixed capacitor causes the RF-radiating antenna element to operate more linearly (i.e., have an improved linear response). In some embodiments, this is achieved by the fixed capacitor reducing harmonic generation.

[0046] In some embodiments, metal-insulator-metal (MIM) capacitors are made entirely of thin-film materials, such as metals and insulators. MIM capacitors can be fabricated on a variety of flexible substrates or on complementary metal-oxide-semiconductor (CMOS) electrical circuits. In some embodiments, the MIM capacitor is appropriately sized to maintain a high overall q factor for the antenna element (e.g., slot and die with tuning element and capacitor) and to have most of the RF voltage drop in itself rather than in the varactor diode. In this way, harmonic generation and self-tuning caused by high RF input power can be substantially mitigated.

[0047] There are many inventions disclosed herein, including, but not limited to, the role of MIM fixed capacitors for high RF input signal power (from an RF signal source) relative to the transmit (TX) power on the TX radiating antenna element that transmits the signal, and the impact of the TX power on the receive (RX) radiating element that receives the signal. For example, for an antenna operating at Ka band, where the number of TX slots is 80,000 and the antenna input power is greater than 16 W, including but not limited to the kilowatt range, the MIM capacitor plays a key role in mitigating RF power from the RF input signal on the varactor in both the ON and OFF states, where the ON state is a state where there is a DC voltage on the varactor and the OFF state is a state where there is no DC voltage on the varactor. When the varactor (tuning element) and MIM capacitor are located within the same die, the voltage on the varactor is the voltage each die sees relative to a portion of the input TX power of the RF input signal from the RF signal source.

[0048] FIG. 3 illustrates the capacitance-voltage (CV) curve of a varactor diode according to some embodiments. Referring to FIG. 3, when the AC / injection signal magnitude is relatively small, the voltage swing of the low-power waveform 301 covers only the region from Cj1 to Cj2, where both values ​​Cj1 and Cj2 are very close to Cj0. Nevertheless, when the RF / injection signal magnitude is relatively large, the high-power waveform 302 swings from a low capacitance of Cj3 to a high value Cj4. This suggests that the effective capacitance should no longer be assumed to be Cj0. In other words, the lower power waveform 301 is in a safe mode and cannot significantly change the varactor capacitance, while the high-power waveform 302 is critical and can significantly change the varactor capacitance.

[0049] To compensate for the effects of input RF power in large metasurface arrays, especially when both RF and DC voltages are received by the varactors coupled to the TX and RX slots to tune the RF radiating antenna elements, fixed capacitors (e.g., MIM capacitors) compensate for the nonlinearities / harmonic generation that occur. Specific benefits of MIMs in this regard include improving the linearity of the system, reducing the capacitance variation of the varactors in high-power TX transmission situations, and reducing the capacitance variation of the varactors in the RX antenna elements when the TX radiating antenna elements are radiating high power.

[0050] 3, in the circuit design of some embodiments of a die including a varactor coupled in series with a varactor, for high power waveforms, the RF power received at each TX element does not affect the capacitance on the varactor, even though the capacitance of the varactor is changed by the DC voltage applied by the varactor's driver (e.g., a matrix driver, etc.) This is due to the use of MIM (fixed) capacitors coupled in series with the varactor.

[0051] FIG. 4 illustrates some embodiments of an RF radiating antenna element with a varactor and MIM capacitor disposed over each slot (iris). Referring to FIG. 4, antenna element 400 includes slot 401. Slot 401 has a long, narrow section (i.e., a vertically elongated section) with a width (extending horizontally in FIG. 4). Varactor 402 is coupled in series with MIM capacitor 403 across the width of slot 401. In some embodiments, varactor 402 is connected in series with MIM capacitor 403. In some embodiments, the coupling of varactor 402 and MIM capacitor 403 is at the center or central portion of slot 401. In some embodiments, the sizes of the MIMs for both RX and TX are different from each other. In some embodiments, for the TX section, the size of the MIM can be in the range of several hundred femtofarads (fF). In Ka band, when the number of TX slots is 80,000 and the antenna input power exceeds 16 W, the MIM plays an important role in suppressing the voltage across the varactor from the RF signal input power from the RF signal source in both the ON and OFF states.

[0052] In some other embodiments, the varactor 402 and MIM capacitor 403 are coupled elsewhere along the slot 401 (e.g., about a quarter of the way from the top or bottom of the slot 401). In some embodiments, the varactor 402 and MIM capacitor 403 are included in an integrated circuit (IC) die coupled across the slot 401, with the MIM capacitor 403 considered a fixed capacitor in the die design. The MIM capacitor 403 is a linear device, and the varactor 402 is a nonlinear device. While the antenna element in FIG. 4 shows the use of an MIM capacitor, other types of fixed capacitors can be used to make the RF radiating antenna element, as well as the overall TX system, operate more linearly by mitigating harmonic generation.

[0053] The antenna element 400 receives an input RF signal power 410 from an RF signal source 420. The RF signal power 410 represents the TX input power received by the antenna element 400. The varactor 402 also receives a DC voltage / power. In some embodiments, the DC voltage comprises a DC voltage 411 from a driver 430 (e.g., a driver of a matrix drive) used to control the varactor 402 as a tuning element.

[0054] FIG. 5 is a graph of the RF voltage of an RF signal received by a varactor and a MIM in the OFF mode (lower band) of a TX element. In OFF mode, there is no DC voltage across the varactor, and the TX antenna element is OFF. Referring to FIG. 5, the graph plots the RF voltage of the RF signal received by the varactor on the horizontal axis and the power received on each TX die that includes a varactor coupled across the slot of the antenna element on the vertical axis. Graph 501 shows the received power on each Tx die that is coupled across the slot and includes a varactor, while graph 502 shows the received power on each TX die that is coupled across the slot and includes a varactor and a MIM capacitor connected in series with the varactor. As shown in the graph of FIG. 5, in OFF mode, beneficially, the value of the series MIM capacitor is approximately 10 times smaller than the varactor capacitance, and most of the RF voltage is affected by the MIM capacitor (as the RF voltage increases) rather than the varactor.

[0055] FIG. 6 shows the RF voltage of the RF signal received by the varactor and MIM in the ON mode (higher band) of the RX element. In ON mode, a DC voltage is applied to the varactor, and the RX antenna element is ON. Referring to FIG. 6, the graph plots the RF voltage of the RF signal received by the varactor on the horizontal axis and the power received on each RX die including a varactor coupled across the slot of the antenna element on the vertical axis. Graph 601 shows the received power on each RX die coupled across the slot and including a varactor, while graph 602 shows the received power on each RX die coupled across the slot and including a varactor and an MIM capacitor connected in series with the varactor. As shown in the graph of FIG. 6, in ON mode, beneficially, the value of the series MIM capacitor is at least 10 times smaller than the varactor capacitance, so that most of the RF voltage of the input RF signal is affected by the MIM capacitor and not by the varactor (as RF input power increases). For example, in OFF mode, the value of the series MIM is approximately 10 times smaller than the varactor capacitance, so that most of the RF voltage of the input RF signal is seen by the MIM, not the varactor.

[0056] 7 is a flow diagram of some embodiments of a process for communicating with a metasurface antenna. Referring to FIG. 7, the process begins by tuning radio frequency (RF) radiating antenna elements of an array of RF radiating antenna elements in a metasurface, where each RF radiating antenna element includes a slot, a tuning element that tunes the slot as part of the RF radiating antenna element that generates a beam, and a fixed capacitor coupled in series with the tuning element across the slot (processing block 701). Tuning the RF radiating antenna elements in the metasurface includes using the fixed capacitor to control the linear response of the radiating antenna element and the system while an RF input signal and a direct current (DC) voltage are applied to the tuning element.

[0057] The process also includes generating at least one beam using the array of RF radiating antenna elements by interacting the RF radiating antenna elements with one or more feed waves based on tuning of the RF radiating antenna elements (processing block 702), and communicating one or more signals with the metasurface using the at least one beam (processing block 703).

[0058] As mentioned above, the technology described herein is not limited to metasurface antennas with metamaterial antenna elements. In some embodiments, the antenna is a phased array antenna including phase shifters with varactor diodes and fixed or static capacitors. For example, the core antenna 102 can alternatively include RF radiating antenna elements with such phase shifters.

[0059] In some embodiments, the phase shifters of such a phased array antenna include loaded line phase shifters. In such a case, in some embodiments, the phased array antenna includes a plurality of signal lines and a plurality of phase shifters. Each phase shifter is coupled to one of the signal lines and includes a plurality of ground planes and a plurality of load elements that couple one signal line to a pair of group planes at periodic positions along the one signal line, each of the plurality of load elements comprising a tuning varactor coupled in series with a fixed capacitor (e.g., a MIM capacitor, etc.).

[0060] 8 illustrates some embodiments of loaded-line phase shifters for phased array antennas. In some embodiments, the loaded-line phase shifters have load elements each having a series combination of a varactor and a fixed (static) capacitor (e.g., an MIM capacitor).

[0061] Referring to FIG. 8, a coplanar waveguide 800 includes a periodic varactor load. A signal line 801 is between two grounds 802 and 803. The signal line 801 is periodically coupled to the grounds 802 and 803 via varactor diodes in series with electrostatic capacitance 804. In other words, the varactor diodes with series-coupled electrostatic capacitance 804 periodically couple to the grounds 802 and 803 at points along the signal line 801, causing the phase shifter to represent a periodic load line due to the varactors. In this way, a phased array antenna using varactor diodes provides improved linearization over one that does not include varactors with fixed (static) capacitors.

[0062] In summary, when using varactors as tuning elements, fixed capacitors (MIM capacitors) are added in series to compensate for both the RF input signal and the DC voltage received at each varactor (tuning element) on the TX and RX dies that are coupled across the slots of the metamaterial antenna element. This provides many benefits in the embodiments disclosed herein, including improved linearity of the TX system including the RF radiating element, reduced capacitance variation of the varactor at high TX power, and reduced capacitance variation on the varactor-RX element when the TX element is radiating high power.

[0063] There are several exemplary embodiments described herein.

[0064] Example 1 is an antenna comprising: a radio frequency (RF) signal source; and a plurality of radio frequency (RF) radiating antenna elements coupled to the RF signal source, each of the RF radiating antenna elements including a slot; a tuning element coupled to the RF signal source for tuning the slot as part of the RF radiating antenna element that generates a beam; and a fixed capacitor coupled to the RF signal source and coupled in series with the tuning element across the slot, the fixed capacitor reducing harmonic generation to control the linear response of the plurality of radio frequency (RF) radiating antenna elements.

[0065] Example 2 is the antenna of example 1, optionally including wherein the fixed capacitor comprises a metal-insulator-metal (MIM) capacitor.

[0066] Example 3 is the antenna of example 2, which can optionally include the MIM capacitor and the tuning element being part of a die.

[0067] Example 4 is the antenna of example 1, optionally including wherein the tuning element comprises a varactor.

[0068] Example 5 is the antenna of Example 1, which can optionally include the fixed capacitor being operable to mitigate generation of harmonics when RF power of the RF signal source received by the tuning element increases in a different mode.

[0069] Example 6 is the antenna of Example 1, which can optionally include the fixed capacitor being operable to reduce capacitance variations at the tuning element of a receive (RX) RF radiating antenna element of a first set of the plurality of RF radiating antenna elements while a transmit (TX) RF radiating antenna element of the plurality of RF radiating antenna elements is radiating.

[0070] Example 7 is the antenna of example 1, optionally including the tuning element having a control input for receiving a direct current (DC) control signal.

[0071] Example 8 is the antenna of example 1, which can optionally include the plurality of antenna elements being part of a metasurface.

[0072] Example 9 is the antenna of example 1, which can optionally include the plurality of RF radiating antenna elements being part of a metasurface.

[0073] Example 10 is an antenna comprising: a radio frequency (RF) signal source; and a plurality of RF radiating antenna elements coupled to the RF signal source, each RF radiating antenna element of the plurality of RF radiating antenna elements comprising: a slot; and a die coupled to the slot and the RF signal source, the die including a tuning element coupled in series with a fixed capacitor, the series-coupled tuning element and the fixed capacitor being coupled across the slot, the tuning element operable to tune the slot based on a direct current (DC) control signal when the RF radiating antenna element generates a beam, and the fixed capacitor operable to cause an improved linear response by each RF antenna element when an associated tuning element receives an AC voltage from the RF signal source and a DC voltage related to the DC control signal.

[0074] Example 11 is the antenna of example 10, which can optionally include the fixed capacitor comprising a metal-insulator-metal (MIM) capacitor.

[0075] Example 12 is the antenna of example 10, which can optionally include the tuning element comprising a varactor.

[0076] Example 13 is the antenna of Example 10, which can optionally include that the fixed capacitor is operable to mitigate harmonic generation when RF power of the RF signal source received by the tuning element increases in different modes.

[0077] Example 14 is the antenna of example 10, which can optionally include the fixed capacitor being operable to reduce capacitance variations of tuning elements of receive (RX) RF radiating antenna elements of a first set of the plurality of RF radiating antenna elements while a transmit (TX) RF radiating antenna element of the plurality of RF radiating antenna elements is radiating.

[0078] Example 15 is the antenna of example 10, which can optionally include the plurality of antenna elements being part of a metasurface.

[0079] Example 16 is a method including tuning radio frequency (RF) radiating antenna elements of an array of RF radiating antenna elements in a metasurface, each RF radiating antenna element including a slot, a tuning element that tunes the slot as part of the RF radiating antenna element that generates a beam, and a fixed capacitor coupled in series with the tuning element across the slot, wherein tuning the RF radiating antenna elements of the RF radiating antenna elements in the metasurface includes controlling the linear response of the plurality of radio frequency (RF) radiating antenna elements using the fixed capacitor while an RF signal and a direct current (DC) voltage are applied to the tuning element, and the method further includes generating at least one beam using the array of RF radiating antenna elements by interacting the RF radiating antenna elements with one or more feed waves based on the tuning of the RF radiating antenna elements, and communicating one or more signals with the metasurface using the at least one beam.

[0080] Example 17 is the method of example 16, which can optionally include the fixed capacitor comprising a metal-insulator-metal (MIM) capacitor.

[0081] Example 18 is the method of example 17, which can optionally include the MIM capacitor and the tuning element being part of a die.

[0082] Example 19 is the method of example 16, which can optionally include the tuning element comprising a varactor.

[0083] Example 20 is the method of example 16, which can optionally include the fixed capacitor being operable to control the linear response of the tuning element as RF power of the RF signal received by the RF radiating antenna element in different modes.

[0084] Example 21 is a phased array antenna comprising: a plurality of signal lines; a plurality of phase shifters, each of which is coupled to one of the plurality of signal lines; a plurality of ground planes; and a plurality of load components coupling the one signal line to a pair of group planes at periodic positions along the one signal line, each of the plurality of load components including a tuning varactor coupled in series with a fixed capacitor.

[0085] Example 22 is the phased array antenna of example 21, which can optionally include that the fixed capacitor includes a MIM capacitor.

[0086] The methods and tasks described herein may be performed by a computer system and may be fully automated. The computer system may, in some cases, include multiple separate computers or computing devices (e.g., physical servers, workstations, storage arrays, cloud computing resources, etc.) that communicate and interoperate over a network to perform the described functions. Each such computing device typically includes a processor (or multiple processors) that executes program instructions or modules stored in memory or other non-transitory computer-readable storage media or devices (e.g., solid-state storage devices, disk drives, etc.). Various functions disclosed herein may be embodied in such program instructions or may be implemented in application-specific circuitry (e.g., ASICs or FPGAs) in the computer system. When a computer system includes multiple computing devices, these devices may, but need not, be co-located. The results of the disclosed methods and tasks may be persistently stored by converting physical storage devices, such as solid-state memory chips or magnetic disks, to different states. In some embodiments, the computer system may be a cloud-based computing system in which processing resources are shared by multiple different business entities or other users.

[0087] Depending on the embodiment, certain operations, events, or functions of any of the processes or algorithms described herein may be performed in a different sequence, added, combined, or eliminated altogether (e.g., not all of the described operations or events are required to implement an algorithm). Furthermore, in particular embodiments, operations or events may be performed simultaneously, e.g., not sequentially, but via multi-threaded processing, interrupt processing, or multiple processors or processor cores or other parallel architectures.

[0088] The various illustrative logic blocks, modules, routines, and algorithm steps described in the embodiments disclosed herein can be implemented as electronic hardware (e.g., an ASIC or FPGA device), computer software running on computer hardware, or a combination of both. Furthermore, the various illustrative logic blocks and modules described in connection with the embodiments disclosed herein can be implemented or performed by machines such as processor devices, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processor device can be a microprocessor, but alternatively, the processor device can be a controller, microcontroller, or state machine, similar combinations, etc. The processor device can include electronic circuitry configured to process computer-executable instructions. In another embodiment, the processor device includes an FPGA or other programmable device that performs logical operations without processing computer-executable instructions. A processor device may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. While described primarily in terms of digital technology herein, a processor device may also include primarily analog components. For example, some or all of the techniques depicted herein may be implemented in analog circuitry or mixed analog and digital circuitry. The computing environment may include any type of computing system, including, by way of example and not limitation, a microprocessor, mainframe computer, digital signal processor, portable computing device, device controller, or computing engine within an appliance.

[0089] Elements of the methods, processes, routines, or algorithms described in connection with the embodiments disclosed herein may be embodied directly in hardware, in software modules executed by a processor device, or in a combination of both. The software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of non-transitory computer-readable storage medium. An exemplary storage medium may be coupled to the processor device such that the processor device can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor device. The processor device and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor device and the storage medium may reside as discrete components in a user terminal.

[0090] In particular, conditional expressions used herein, such as "can," "could," "might," "may," and "e.g.," are generally intended to convey that certain embodiments include certain features, elements, or steps, and that other embodiments do not, unless expressly indicated otherwise or understood otherwise within the context of use. Thus, such conditional expressions generally do not imply that features, elements, or steps are more or less required for one or more embodiments, or that they necessarily include logic that determines, with or without other input or instruction, whether or not these features, elements, or steps are included in or should be performed in any particular embodiment. Terms such as "comprising," "including," and "having" are synonymous and used in an inclusive, open-ended manner and do not exclude additional elements, features, acts, operations, etc. Also, when the word "or" is used, for example, to connect lists of elements, "or" is used in an inclusive (not exclusive) sense to mean one, some, or all of the elements in the list.

[0091] Unless expressly indicated otherwise, disjunctive language such as "at least one of X, Y, or Z" is generally understood in the context in which it is commonly used to indicate that an item, term, etc. can be either X, Y, or Z, or any combination thereof (e.g., X, Y, or Z). Thus, such disjunctive language is generally not intended, and should not be intended, to indicate that a particular embodiment requires that at least one of X, at least one of Y, and at least one of Z are each present.

[0092] The foregoing detailed description illustrates, describes, and points out novel features added to the various embodiments, and it will be understood that various omissions, substitutions, and changes in the form and details of the illustrated devices or algorithms may be made without departing from the spirit of the disclosure. As will be recognized, some features can be used or practiced separately from other features, and therefore particular embodiments described herein can be practiced in forms that do not provide all of the features and advantages set forth herein. The scope of the particular embodiments disclosed herein is indicated by the appended claims, rather than by the foregoing specification. All changes that come within the meaning and range of equivalency of the claims are intended to be embraced within their scope. [Explanation of symbols]

[0093] 400 antenna elements 401 Slots 402 Varactor 403 MIM capacitor 404 Conductor 411 DC voltage from driver to varactor 410 Input RF power (e.g., TX input power) 420 RF signal source 430 driver

Claims

1. An antenna, a radio frequency (RF) signal source; a plurality of radio frequency (RF) radiating antenna elements coupled to the RF signal source; Equipped with each of the RF radiating antenna elements: Slots and a tuning element coupled to the RF signal source for tuning the slot as part of the RF radiating antenna element to generate a beam; a fixed capacitor coupled to the RF signal source and coupled in series with the tuning element across the slot, the fixed capacitor mitigating harmonic generation to control a linear response of the plurality of radio frequency (RF) radiating antenna elements; Including, an antenna.

2. The antenna of claim 1 , wherein the fixed capacitor comprises a metal-insulator-metal (MIM) capacitor.

3. The antenna of claim 2 wherein the MIM capacitor and the tuning element are part of a die.

4. The antenna of claim 1 , wherein the tuning element comprises a varactor.

5. 2. The antenna of claim 1, wherein the fixed capacitor is operable to mitigate harmonic generation when RF power of the RF signal source received by the tuning element increases in different modes.

6. 2. The antenna of claim 1, wherein the fixed capacitor is operable to reduce capacitance variations at the tuning elements of receive (RX) RF radiating antenna elements of a first set of the plurality of RF radiating antenna elements while transmit (TX) RF radiating antenna elements of the plurality of RF radiating antenna elements are radiating.

7. 10. The antenna of claim 1, wherein the tuning element has a control input for receiving a direct current (DC) control signal.

8. The antenna of claim 1 , wherein the plurality of antenna elements are part of a metasurface.

9. The antenna of claim 1 , wherein the plurality of RF radiating antenna elements are part of a metasurface.

10. An antenna, a radio frequency (RF) signal source; a plurality of RF radiating antenna elements coupled to the RF signal source; Equipped with Each RF radiating antenna element of the plurality of RF radiating antenna elements is Slots and a die coupled to the slot and the RF signal source, the die including a tuning element coupled in series with a fixed capacitor, the series coupled tuning element and the fixed capacitor coupled across the slot; Equipped with The antenna, wherein the tuning elements are operable to tune the slots based on a direct current (DC) control signal when the RF radiating antenna elements generate a beam, and the fixed capacitors are operable to cause an improved linear response by each RF antenna element when an associated tuning element receives an AC voltage from the RF signal source and a DC voltage related to the DC control signal.

11. The antenna of claim 10 , wherein the fixed capacitor comprises a metal-insulator-metal (MIM) capacitor.

12. The antenna of claim 10 wherein the tuning element comprises a varactor.

13. 11. The antenna of claim 10, wherein the fixed capacitor is operable to mitigate harmonic generation when RF power of the RF signal source received by the tuning element increases in different modes.

14. 11. The antenna of claim 10, wherein the fixed capacitor is operable to reduce capacitance variations of tuning elements of receive (RX) RF radiating antenna elements of a first set of the plurality of RF radiating antenna elements while transmit (TX) RF radiating antenna elements of the plurality of RF radiating antenna elements are radiating.

15. The antenna of claim 10 , wherein the plurality of antenna elements are part of a metasurface.

16. 1. A method comprising: tuning radio frequency (RF) radiating antenna elements of an array of RF radiating antenna elements in the metasurface; each said RF radiating antenna element: Slots and a tuning element for tuning the slot as part of the RF radiating antenna element to generate a beam; a fixed capacitor coupled in series with the tuning element across the slot; Including, Tuning the RF radiating antenna elements of the metasurface includes controlling a linear response of the plurality of radio frequency (RF) radiating antenna elements using the fixed capacitor while an RF signal and a direct current (DC) voltage are applied to the tuning elements; The method further comprises: generating at least one beam using the array of RF radiating antenna elements by interacting the RF radiating antenna elements with one or more feed waves based on tuning of the RF radiating antenna elements; communicating one or more signals to the metasurface using the at least one beam; A method comprising:

17. The method of claim 16 , wherein the fixed capacitor comprises a metal-insulator-metal (MIM) capacitor.

18. The method of claim 17 , wherein the MIM capacitor and the tuning element are part of a die.

19. The method of claim 16 , wherein the tuning element comprises a varactor.

20. 17. The method of claim 16, wherein the fixed capacitor is operable to control the linear response of the tuning element as a function of RF power of the RF signal received by the RF radiating antenna element in different modes.

21. A phased array antenna, A plurality of signal lines; a plurality of phase shifters; Equipped with each phase shifter of the plurality of phase shifters is coupled to one signal line of the plurality of signal lines; a plurality of ground planes; a plurality of load components coupling the one signal line to a pair of group planes at periodic positions along the one signal line, each of the plurality of load components including a tuning varactor coupled in series with a fixed capacitor; A phased array antenna comprising:

22. 22. The phased array antenna of claim 21, wherein the fixed capacitor comprises a metal-insulator-metal (MIM) capacitor.

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