Antenna

Abstract

Antenna and method for manufacturing the antenna According to one aspect of the present invention, there is provided an antenna including a magnetostrictive layer configured to convert a magnetic field of a detected electromagnetic wave into mechanical strain in a reception mode, and a piezoelectric layer configured to receive the strain from the magnetostrictive layer and generate a voltage output based thereon in the reception mode, wherein the piezoelectric layer includes a memristive material.

Description

Technical Field

[0001] The present invention generally relates to antennas, and more particularly to antennas including memristive materials. Related antenna arrays and methods are also provided.

Background Art

[0002] Wireless communication systems operating in the radio frequency range require antennas to convert electromagnetic waves into currents indicative of received signals and vice versa. Typically, an antenna is driven by an analog circuit connected to a signal processing unit. In most systems, the signal received by the antenna does not move directly to the logic elements responsible for decoding the signal and extracting the transmitted information. Instead, the signal usually has to pass through modules such as an analog-to-digital (ADC) converter, memory, and / or a digital signal processor (DSP). Each of these modules has a related noise source, thereby degrading the signal-to-noise ratio (SNR) of the system.

[0003] Furthermore, such modules include parasitic elements that introduce propagation delays, increasing the time interval between the signal received by the antenna and the information contained in the extracted signal. Therefore, different approaches are needed to provide a device that can extract the information contained in the received signal more quickly.

[0004] An exemplary object of an exemplary embodiment of the present invention, whether specified herein or elsewhere, is to at least partially avoid or overcome one or more drawbacks of the prior art, or at least provide a practicable alternative to existing devices and methods.

Summary of the Invention

[0005] According to one aspect of the present invention, in a receiving mode, there is provided an antenna including a magnetostrictive layer configured to convert a magnetic field of a detected electromagnetic wave into mechanical strain, and a piezoelectric layer configured to receive the strain from the magnetostrictive layer in the receiving mode and generate a voltage output based thereon, wherein the piezoelectric layer includes a memristive material. Accordingly, an antenna having inherent memory and signal processing capabilities can be provided, thereby enabling faster extraction of information contained in a received signal. Computation can be performed directly in the memory element, and the memory element also performs a sensing operation, thereby detecting and processing the received signal.

[0006] In a transmitting mode, the piezoelectric layer can be configured to receive a voltage input and generate mechanical strain based thereon, and the magnetostrictive layer can be configured to receive the mechanical strain generated by the piezoelectric layer and generate and output an electromagnetic wave based thereon. Accordingly, in addition to reception, the antenna can use a piezoelectric layer including a memristive material in signal transmission.

[0007] The piezoelectric layer may be arranged to be set to specified conditions by application of a voltage and / or charge. Accordingly, due to the inherent characteristics of the memristive material contained therein, the piezoelectric layer can be set to desired conditions in an easy manner.

[0008] The piezoelectric layer may be configured to be set to specified conditions before the receiving and / or transmitting operation of the antenna is performed. Accordingly, the antenna can be preset (in other words, pre-programmed) before normal use, and thus can be regarded as a programmable system.

[0009] Setting the piezoelectric layer to defined conditions may include changing the conductance of the piezoelectric layer by applying a voltage. The conductance of the memristive material is closely related to the synaptic load, i.e., the strength of the synaptic connection. Therefore, by applying a voltage, the conductance can be decreased and / or increased to realize the forgetting and learning behaviors of the piezoelectric layer, respectively, thereby exhibiting synaptic behavior similar to that of a biological system.

[0010] The conductance of the piezoelectric layer can be changed based on at least one of the frequency of the applied voltage and the polarity of the applied voltage. Since the conductance of the memristive material depends on the shape and frequency of the stimulated pulse, the characteristics of the piezoelectric layer can be easily changed.

[0011] The piezoelectric layer may be configured to hold the set conditions after the application of the voltage. Therefore, the piezoelectric layer can function as a non-volatile memory due to the presence of the memristive material.

[0012] The piezoelectric layer can be configured to generate a voltage output based on the received strain of the piezoelectric layer and the charge resulting from the set conditions. Thereby, the antenna can generate an output not only based on the detection signal but also based on the set state of the piezoelectric layer.

[0013] The piezoelectric layer may be configured to generate a voltage output when the charge resulting from the received strain is equal to a threshold value defined based on the set conditions of the piezoelectric layer. Therefore, the antenna can ignore signals without the desired characteristics as noise and generate an output only when a pre-programmed signal pattern is acquired. This is done by the antenna without interaction with an additional processing unit, thereby reducing the signal propagation delay and thus the time it takes for the antenna to extract information from the desired signal.

[0014] The memristive material can include annealed aluminum nitride (AlN). Therefore, the antenna can be manufactured using readily available materials, thereby improving manufacturability and reducing costs.

[0015] According to another aspect of the present invention, an antenna array comprising a plurality of antennas described herein is provided. Therefore, an antenna with inherent signal processing capabilities can be provided, thereby enabling faster extraction of information contained in the received signal. The calculations can be performed directly in the memory element, which also performs the sensing operation, thereby detecting and processing the received signal.

[0016] Each of the plurality of antennas of the antenna array can be arranged to be individually set to conditions defined by the application of a voltage. Therefore, each of the individual antennas can be set to conditions that enable the identification of a specific signal, thereby achieving higher programmability.

[0017] According to another aspect of the present invention, a method of manufacturing an antenna is provided, the method including providing a piezoelectric layer including a memristive material and providing a magnetostrictive layer disposed on the piezoelectric layer. Therefore, an antenna with inherent signal processing capabilities can be provided, thereby enabling faster extraction of information contained in the received signal. The calculations can be performed directly in the memory element, which also performs the sensing operation, thereby detecting and processing the received signal.

[0018] The method can include providing annealed aluminum nitride (AlN) as the memristive material. Therefore, the antenna can be manufactured using readily available materials, thereby reducing costs.

Brief Description of the Drawings

[0019] Next, embodiments of the present invention will be described by way of example only with reference to the accompanying drawings.

Figure 1

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[0020] As described above, existing antennas have many drawbacks. These range from the significant cost associated with existing antennas due to the amount of circuitry required, to the delay in extracting information from the signals received by the antenna, or the amount of noise that is erroneously picked up instead of the desired signal. In general, there is no relatively inexpensive, flexible, and simple design that enables an antenna to process received signals in an element that also performs a sensing operation.

[0021] According to the present disclosure, it has been recognized that the problems associated with existing techniques can be overcome in an inexpensive and effective manner. In particular, the present disclosure provides a magnetoelectric antenna including a memristive material.

[0022] FIG. 1 schematically depicts an antenna according to an exemplary embodiment. In this example, antenna 100 includes a magnetostrictive layer 102 and a pressure transmission 104. Importantly, piezoelectric layer 104 includes a memristive material.

[0023] Antenna 100 may be a thin film bulk acoustic resonator (FBAR) antenna. Since antenna 100 operates at an acoustic resonance frequency rather than an EM wave resonance frequency, the size of the antenna can be significantly reduced to a size comparable to the electromagnetic wavelength without performance degradation. Thus, antenna 100 may be particularly suitable for use in applications where a high resonance frequency, small size, and low weight are desirable.

[0024] Antenna 100 transmits and receives electromagnetic waves by means of the magnetoelectric effect at its acoustic resonance frequency. During the reception operation of antenna 100, the magnetostrictive layer 102 is configured to convert the detected magnetic field of the electromagnetic wave into mechanical strain to be received by the piezoelectric layer 104. The piezoelectric layer 104 generates a voltage output based on the strain received from the magnetostrictive layer 102. Specifically, in the reception mode, the magnetostrictive layer 102 senses the H component of the electromagnetic wave and induces a vibrational deformation that is transmitted to the piezoelectric layer 104. The piezoelectric layer 104 can then generate a voltage output.

[0025] Conversely, during the transmission operation of antenna 100, the piezoelectric layer 104 is configured to receive a voltage input and generate mechanical strain based thereon. Such a voltage input can originate from antenna 100 itself or from external components of the antenna system. The magnetostrictive layer 102 receives the mechanical strain generated by the piezoelectric layer 104 and is configured to generate and output an electromagnetic wave based thereon. Specifically, the piezoelectric layer 104 can receive an input of an alternating voltage and generate a mechanical deformation that vibrates. In response to the mechanical excitation, the magnetostrictive layer 102 can then induce a magnetization vibration or magnetic current that radiates an electromagnetic wave and thus transmits a signal.

[0026] As described above, the piezoelectric layer 104 includes a memristive material. In particular, the memristive material exhibits non-volatile memory characteristics and continuous conductance change characteristics, and thus is suitable for use in neuromorphic systems. The memristive material can be compared to synapses in the brain.

[0027] The cellular mechanisms underlying learning and memory in the human and animal brain are called long-term potentiation (LTP). LTP is a persistent strengthening of synapses based on recent activity patterns. These are patterns of synaptic activity that result in a long-lasting increase in signal transmission between two neurons. Short-term potentiation (STP) refers to the process by which synaptic transmission is transiently enhanced. Thus, STP can be considered short-term memory. STP can change to LTP through a process of repeated impressions that includes many biological changes.

[0028] Generally, a memristor (i.e., a memristive device) is a two-terminal resistive switching device that can maintain its internal resistance state according to the history of the applied voltage / current. The two terminals behave similarly to the axon and dendrite connecting the presynaptic neuron and the postsynaptic neuron of a synapse, and the conductance of the switching layer is comparable to the synaptic weight. By changing the conductance of the memristor to a set state, the device can be used to realize the memory function of the human brain by simulating the change from the non-memorized state to the STP state and the LTP state.

[0029] The piezoelectric layer 104 may be set to specified conditions by the application of a voltage. Setting the piezoelectric layer 104 to the specified conditions may include changing the conductance of the piezoelectric layer 104 by the application of a voltage or charge. In particular, by applying a voltage to the piezoelectric layer 104, the conductance of the memristive material contained in the piezoelectric layer 104 can be changed, thereby realizing the memory function described above. The voltage applied to the piezoelectric layer 104 may be an external bias voltage / charge or an internal charge generated by the antenna 100 due to the piezoelectric effect.

[0030] Similarly, since the two quantities are essentially related, the electrical resistance of the piezoelectric layer 104 can also be modified through the application of a voltage. In particular, the resistance of the memristive material contained in the piezoelectric layer 104 can be changed in this way.

[0031] The conditions (or state) of the piezoelectric layer 104 may depend on the previous state, the amplitude of the applied voltage, and the acquisition time of the voltage / signal. For example, after the application of the first voltage, the conditions of the piezoelectric layer 104 can be changed from the initial state to the first state. After the first voltage is applied, when a second voltage is applied to the piezoelectric layer 104, the conditions of the piezoelectric layer 104 change from the first state to the second state.

[0032] The conductance of the piezoelectric layer 104 can be changed based on at least one of the frequency of the applied voltage and the polarity of the applied voltage. For example, by applying continuous positive voltage pulses, the conductance of the memristive material included in the piezoelectric layer 104 can be changed from the initial state to a higher state. Conversely, by applying negative voltage pulses, the conductance of the memristive material 104 can be changed from the initial state to a lower state. The conductance of the memristive material can also be changed by modifying the duration of the applied voltage.

[0033] The piezoelectric layer 104 may be configured to retain the conditions set after the application of the voltage. As described above, a voltage can be applied to change the conductance of the memristive material included in the piezoelectric layer 104, which can be changed from the initial state to a higher state. This change in the conductance of the memristive material is retained for a period after the application of the voltage stops, thereby enabling non-volatile memory operation of the memristive material. In other words, it is not necessary to apply a constant voltage to change the conductance of the memristive material within the piezoelectric layer 104. By changing the conductance / resistance of the memristive material included in the piezoelectric layer 104, the resonance frequency of the antenna 100 can be changed.

[0034] The retention time can be defined as the amount of time that the piezoelectric layer 104 retains its set state. For example, it can be defined as the amount of time that the memristive material included in the piezoelectric layer 104 retains its changed conductance state. The retention time can be increased by increasing at least one of the number of voltage pulses, the pulse width, and / or the pulse amplitude.

[0035] The piezoelectric layer 104 can be arranged to be set to a specified condition before the receiving and / or transmitting operation of the antenna is performed. In this way, the antenna 100 can be pre-programmed or pre-set to defined conditions.

[0036] As described above, strain is generated by the magnetostrictive layer 102 by converting the detected electromagnetic wave, i.e., the magnetic field of the signal detected by the antenna 100. The piezoelectric layer 104 can be configured to generate a voltage output based on the strain received by the piezoelectric layer 104 and the charge resulting from the set conditions. Therefore, the voltage output generated by the piezoelectric layer 104 can depend not only on the detected electromagnetic wave but also on the set conditions of the piezoelectric layer 104. For example, the voltage output can depend on the received strain resulting from the detected electromagnetic wave and the changed conductance of the memristive material included in the piezoelectric layer 104.

[0037] The piezoelectric layer 104 may be configured to generate a voltage output when the charge resulting from the received strain is equal to a threshold value defined based on the set conditions of the piezoelectric layer. That is, the piezoelectric layer 104 may be configured to generate a voltage output only when a pre-programmed signal pattern is obtained. The piezoelectric layer 104 may be pre-programmed to respond to a specific signal pattern by utilizing the memory ability of the memristive material included therein. This can be achieved by setting the piezoelectric layer 104 to the specified conditions corresponding to the signal pattern that the user wants to detect.

[0038] Specifically, the process of signal recognition by the memristive material included in the piezoelectric layer 104 can utilize the switching characteristics of the memristor. As described above, by applying a voltage, the conductance and resistance of the memristive material can be changed.

[0039] FIG. 2 schematically depicts a thin-film bulk acoustic resonator (FBAR) 200 with a piezoelectric layer according to an exemplary embodiment. The piezoelectric layer can be regarded as equivalent to the piezoelectric layer 104 shown in FIG. 1. The piezoelectric layer is sandwiched between a first electrode 210 (e.g., the upper electrode) and a second electrode 216 (e.g., the lower electrode), thereby forming a thin-film bulk acoustic resonator (FBAR) 200.

[0040] The piezoelectric layer can comprise a plurality of layers. The plurality of layers of the piezoelectric layer can include a switchable resistance layer 212. The resistance of the switchable resistance layer 212 may be variable between a high resistance state and a low resistance state. The plurality of layers can also include a capacitance layer 214.

[0041] The charge generated by the piezoelectric layer caused by the detected electromagnetic wave can modulate the voltage across the capacitance layer 214 of the memristive material included in the piezoelectric layer. The overall resistance / impedance of the antenna 100 can be controlled by the switchable resistance layer 212. The resulting change in at least one of the conductance, resistance, impedance, and capacitance of the memristive material included in the piezoelectric layer can modulate the resonance frequency of the FBAR 200, thereby changing the resonance frequency of the antenna 100.

[0042] As described above, the antenna 100 operates by converting an electromagnetic signal into mechanical strain generated in the magnetostrictive layer 102. The mechanical strain transmitted to the piezoelectric layer 104 is converted into a voltage. Specifically, a potential difference is induced in the capacitive layer 214 thereby. When the voltage across the capacitive layer 214 reaches the switching threshold, switching can occur in the memristive material. The switching threshold may be pre-programmed in the memristive material. The switching threshold can be correlated with a known signal pattern expected to trigger switching in the memristive material, such that switching occurs only when a desired signal pattern is detected by the antenna 100.

[0043] Signals that do not correspond to the desired signal pattern may be treated as noise by the antenna 100 and may be dropped during reception. That is, such signals may not trigger switching of the memristive material.

[0044] The memristive material can include annealed aluminum nitride (AlN). However, those skilled in the art will understand that other piezoelectric materials exhibiting memristive properties can also be used.

[0045] Annealing can include O2 annealing. O2 annealing can reduce the number of oxygen vacancies at the interface between the aluminum nitride layer and the top electrode of the FBAR. A high dielectric thin film can be formed through a heat treatment process. This high relative permittivity layer enables the memristive material to exhibit synaptic behavior.

[0046] Importantly, the above-described configuration of the antenna 100 is particularly useful when it is necessary to quickly detect and identify signals having specific characteristics. Since the piezoelectric layer 104 uses the memristive material contained therein to trigger a response only when a desired signal pattern is detected, the need for interaction with a processing unit (such as a digital signal processor) is significantly reduced or eliminated. This enables calculations to be performed in the piezoelectric layer 110 without changing the mechanical rigidity of the piezoelectric layer 104, thereby reducing its compliance and the efficiency of electromagnetic wave signal conversion. Therefore, improvements can be achieved for existing systems by enabling signal processing in the piezoelectric layer 110 without changing the mechanical state of the piezoelectric layer 104.

[0047] Furthermore, by enabling direct signal processing within the antenna 100, the signal path can be shortened, and thus the speed at which information can be extracted from the detected signal can be accelerated. Therefore, the antenna 100 may be suitable for applications where minimal latency is required, such as detecting radio frequency (RF) signal patterns reflected from fast-moving objects.

[0048] FIG. 3 schematically depicts an antenna array comprising a plurality of antennas according to an exemplary embodiment. The antenna array 1000 comprises a plurality of antennas 100. The resonance frequencies of the plurality of antennas 100 may be the same. Alternatively or additionally, the respective resonance frequencies of the plurality of antennas 100 may be different such that a plurality of different resonance frequencies can be independently sensed. That is, each of the plurality of antennas 100 may be arranged to be individually set to conditions defined by the application of a voltage to enable multi-channel operation. The detected electromagnetic waves can be processed in parallel by each antenna 100 of the antenna array 1000. This can be achieved by using a network of row multiplexer 302 and column multiplexer 304 to individually address each antenna 100 of the antenna array 1000.

[0049] Figure 4 schematically depicts a method of manufacturing an antenna according to an exemplary embodiment. The antenna may be, for example, the antenna 100 described herein. This method includes, at step 402, providing a piezoelectric layer that includes a memristive material. As described above in connection with FIG. 1, since the piezoelectric layer uses the memristive material contained therein to trigger a response only when a desired signal pattern is detected, the need for interaction with a processing unit (such as a digital signal processor) is significantly reduced or eliminated. Further, by enabling direct signal processing within the antenna, the signal path can be shortened, and thus the speed at which information can be extracted from the detected signal can be accelerated.

[0050] At step 404, the method includes providing a magnetostrictive layer disposed on the piezoelectric layer. In another embodiment, the method may first include the step of providing the magnetostrictive layer, and the piezoelectric layer includes a memristive material disposed on the magnetostrictive layer. By alternating the order of the layers, the performance of the antenna for a particular application can be improved according to a particular design. The method can also include providing a plurality of vertical stacks of the piezoelectric-magnetostrictive layer pair.

[0051] The method may further include the step of providing annealed aluminum nitride (AlN) as the memristive material. However, those skilled in the art will understand that other piezoelectric materials exhibiting memristive properties may also be used.

Claims

1. An antenna, comprising: a magnetostrictive layer configured to convert a magnetic field of a detected electromagnetic wave into mechanical strain in a reception mode; a piezoelectric layer configured to receive the strain from the magnetostrictive layer and generate a voltage output based thereon in the reception mode; wherein the piezoelectric layer comprises a memristive material, the antenna.

2. In a transmission mode, the piezoelectric layer is configured to receive a voltage input and generate mechanical strain based thereon, and the magnetostrictive layer is configured to receive the mechanical strain generated by the piezoelectric layer and generate and output an electromagnetic wave based thereon, the antenna according to claim 1.

3. The antenna according to claim 1 or 2, wherein the piezoelectric layer is arranged to be set to a specified state by application of a voltage and / or charge.

4. The antenna according to claim 3, wherein the piezoelectric layer is arranged to be set to the specified condition before a reception operation and / or a transmission operation of the antenna is performed.

5. Setting the piezoelectric layer to the specified condition comprises changing a conductance of the piezoelectric layer by application of the voltage, the antenna according to claim 3 or 4.

6. The conductance of the piezoelectric layer varies based on at least one of a frequency of an applied voltage and a polarity of the applied voltage, the antenna according to claim 5.

7. The antenna according to any one of claims 3 to 6, wherein the piezoelectric layer is configured to maintain the set condition after application of the voltage.

8. The antenna according to any one of claims 3 to 7, wherein the piezoelectric layer is configured to generate the voltage output based on the received strain of the piezoelectric layer and charge resulting from the set condition.

9. The antenna according to claim 8, wherein the piezoelectric layer is configured to generate the voltage output when charge resulting from the received strain is equal to a threshold value defined based on the set condition of the piezoelectric layer.

10. The antenna according to any one of claims 1 to 9, wherein the memristive material comprises annealed aluminum nitride (AlN).

11. An antenna array comprising a plurality of antennas according to any one of claims 1 to 10.

12. The antenna array according to claim 11, wherein each of the plurality of antennas is arranged to be individually set to conditions defined by the application of a voltage.

13. A method of manufacturing an antenna, comprising: providing a piezoelectric layer including a magnetostrictive material; and providing a magnetostrictive layer disposed on the piezoelectric layer.

14. The method according to claim 13, further comprising providing annealed aluminum nitride (AlN) as the magnetostrictive material.

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