FIELD
[0001] The present invention relates to an antenna. More specifically, the present invention
relates to an antenna comprising a transducer arrangement to produce displacement
of the surface of a magnetostrictive layer of the antenna. A related frequency selective
surface, vehicle, structure and method are also provided.
BACKGROUND
[0002] A wireless communication system operating in a radio frequency range requires an
antenna to convert an electromagnetic wave into an electrical current indicative of
the received signal and vice versa. Selective control of electromagnetic (EM) waves
received and/or transmitted by antenna is limited. Furthermore, a common problem with
classical antenna is the effect of thermal losses.
[0003] Metasurface antennas are known. Metasurface antennas are designed to have particular
signal receiving/transmission characteristics. However, they are typically limited
in their adjustability. That is, metasurface antennas may be designed to receive or
transmit EM waves of a particular frequency, with limited adjustment of said frequency
or bandwidth.
[0004] Frequency selective surfaces are designed to reflect, transmit or absorb EM radiation
of a particular frequency. However, they also have limited adjustability of the selected
frequency. Furthermore, existing frequency selective surfaces have limited beam steering
capabilities.
[0005] It is an example aim of example embodiments of the present invention to at least
partially avoid or overcome one or more disadvantages of the prior art, whether identified
herein or elsewhere, or to at least provide an alternative to existing antenna and
methods.
SUMMARY
[0006] According to a first aspect, there is provided an antenna comprising: an antenna
element comprising: a magnetostrictive layer; and a piezoelectric layer, wherein the
antenna further comprises a transducer arrangement comprising: one or more transducers
operable to generate a mechanical strain field in the antenna element to produce displacement
of the surface of the magnetostrictive layer.
[0007] In one example, in a receive mode, the magnetostrictive layer is configured to convert
a magnetic field of a detected electromagnetic wave into mechanical strain, and the
piezoelectric layer is configured to receive the mechanical strain from the magnetostrictive
layer and produce a voltage and/or charge output based thereon.
[0008] In one example, in a transmit mode, the piezoelectric layer is configured to receive
a voltage and/or charge input and produce mechanical strain based thereon, and the
magnetostrictive layer is configured to receive the mechanical strain produced by
the piezoelectric layer to produce and output an electromagnetic wave based thereon.
[0009] In one example, the antenna element is operable to detect an environmental characteristic
in a region surrounding the antenna element, and the transducer arrangement is operable
to generate mechanical strain field in the antenna element based on the environmental
characteristic.
[0010] In one example, the piezoelectric layer comprises a memristive, memcapacitive or
complex memimpedance characteristic.
[0011] In one example, the piezoelectric layer is arranged to be set to a defined non-volatile
condition by application of a voltage and/or charge.
[0012] In one example, the piezoelectric layer is provided with electrical contacts to provide
an electrical connection to driving circuitry.
[0013] In one example, the transducer arrangement comprises a plurality of transducers operable
to generate a mechanical strain field interference pattern in the antenna element.
[0014] In one example, the transducer arrangement comprises one or more waveguides.
[0015] In one example, the antenna comprises an antenna element array comprising a plurality
of antenna elements.
[0016] In one example, the antenna element array is a honeycomb antenna element array of
hexagonal shape antenna elements.
[0017] In one example, one or more antenna elements are provided with one or more dedicated
transducers.
[0018] In one example, one or more transducers of the transducer arrangement are operable
to generate a mechanical strain field in a plurality of antenna elements.
[0019] In one example, the antenna further comprises one or more reflectors configured to
reflect a mechanical strain wave generated by the one or more transducers. The one
or more reflectors may be one or more acoustic reflectors.
[0020] According to a second aspect, there is provided a frequency selective surface comprising
an antenna according to the first aspect.
[0021] In one example, the transducer arrangement is operable to tune the frequency selective
surface.
[0022] According to a third aspect, there is provided a vehicle or structure comprising
an antenna according to the first aspect or a frequency selective surface according
to the second aspect.
[0023] According to a fourth aspect, there is provided a method of manufacturing an antenna,
comprising providing: an antenna element comprising: a magnetostrictive layer; and
a piezoelectric layer, and a transducer arrangement comprising: one or more transducers
operable to generate a mechanical strain field in the antenna element to produce displacement
of the surface of the magnetostrictive layer.
[0024] It will of course be appreciated that features described in relation to one aspect
of the present invention may be incorporated into other aspects of the present invention.
In particular, the method of the fourth aspect may comprise any or all of the features
of the first to third aspects, as desired or as appropriate.
[0025] Other preferred and advantageous features of the invention will be apparent from
the following description.
BRIEF DESCRIPTION OF THE FIGURES
[0026] Embodiments of the invention will now be described by way of example only with reference
to the figures, in which:
Figure 1 shows an antenna;
Figure 2 shows an antenna comprising an antenna element array; and
Figure 3 shows a frequency selective surface;
Figure 4 shows a vehicle;
Figure 5 shows a structure; and
Figure 6 shows general methodology principles.
DETAILED DESCRIPTION
[0027] In overview, an antenna is provided with the ability to shape antenna surface geometry
by generating a mechanical strain field in the antenna. The reception or transmission
of electromagnetic (EM) waves using the antenna having a particular surface geometry
generates a corresponding antenna radiation pattern.
[0028] Referring to Figure 1, an antenna 10 is shown. The antenna 10 comprises an antenna
element 100. The antenna element 100 comprises a magnetostrictive layer 102 and a
piezoelectric layer 104. The magnetostrictive layer 102 and piezoelectric layer 104
may be said to be "coupled", as will be apparent from the description of the receiving
and transmitting operations below.
[0029] The antenna 10 receives and transmits electromagnetic waves through the magnetoelectric
effect at its acoustic resonance frequency. During a receiving operation of the antenna
10, the magnetostrictive layer 102 is configured to convert a magnetic field of a
detected electromagnetic wave into mechanical strain, to be received by the piezoelectric
layer 104. The piezoelectric layer 104 produces a voltage and/or charge output based
on the strain received from the magnetostrictive layer 102. In detail, in receive
mode, the magnetostrictive layer 102 may sense H-components of electromagnetic waves,
which induce an oscillating strain transferred to the piezoelectric layer 104. The
piezoelectric layer 104 may then produce a voltage and/or charge output.
[0030] Conversely, during a transmitting operation of the antenna 10, the piezoelectric
layer 104 is configured to receive a voltage and/or charge input and produce mechanical
strain based thereon. Such voltage and/or charge input may originate from the antenna
10 itself, or from an external component of an antenna system. Whilst not illustrated
in the figures, the piezoelectric layer 104 may be provided with electrical contacts
to provide an electrical connection to driving circuitry. The magnetostrictive layer
102 is configured to then receive the mechanical strain produced by the piezoelectric
layer 104 to produce and output an electromagnetic wave based thereon. In detail,
the piezoelectric layer 104 may receive an alternating voltage and/or charge input
to produce an oscillating mechanical strain. In response to the mechanical excitation,
the magnetostrictive layer 102 may then induce a magnetisation oscillation, or a magnetic
current, that radiates electromagnetic waves to therefore transmit a signal.
[0031] Importantly, the antenna further comprises a transducer arrangement 106. The transducer
arrangement 106 comprises one or more transducers 108. The one or more transducers
108 are operable to generate a mechanical strain field in the antenna element 100
to produce displacement of the surface of the magnetostrictive layer 102. The one
or more transducers 108 may be surface acoustic wave resonators. The one or more transducers
108 may comprise on or more piezoelectric devices. The one or more transducers 108
may otherwise be referred to as "acoustic actuators", operable to generate vibrations
in the antenna element 100 by providing acoustic energy. Whilst it is noted that the
transducers 108 are operable to generate a mechanical strain field to produce displacement
of the magnetostrictive layer 102, it will be appreciated that displacement of the
piezoelectric layer 104 will also occur.
[0032] Displacement of the surface of the magnetostrictive layer 102 due to the generation
of the mechanical strain field by the one or more transducers 108 impacts the generation
of, or response to, mechanical strain in the magnetostrictive layer 102. For the avoidance
of doubt, the mechanical strain utilised to generate or receive electromagnetic waves
is not the same as the mechanical strain field generated by the one or more transducers
108. It will be appreciated that magnetoelectric effect (i.e., in the receive mode
or transmit mode) makes use of mechanical strain to receive and transmit electromagnetic
waves using the antenna 10, but the present antenna 10 also advantageously makes use
of a mechanical strain field produced by the one or more transducers 108 in order
to control the antenna radiation pattern (i.e., to affect the mechanical strain in
the receive mode or transmit mode). That is, the antenna 10 would still operate, making
use of mechanical strain, in the absence of the one or more transducers 108, however
the one or more transducers generate a mechanical strain field which impacts the response
of the antenna 10 to the mechanical strain. This will be described in further detail
herein.
[0033] As above, the one or more transducers 108 are operable to generate a mechanical strain
field in the antenna element 100. The operation of the one or more transducers 108
vibrates the surface of the antenna element 100 to excite standing waves. This results
in the generation of a surface pattern, or field, consisting of regions of relatively
high (or higher) strain and regions of relatively low (or lower) strain. That is,
a mechanical strain field is set up in the antenna element 100 comprising regions
of high strain and regions of low strain in the magnetostrictive layer 102.
[0034] It follows that in the transmit mode, the regions of relatively high strain are difficult
to excite whereas the regions of relatively low strain are easier to excite. Thus,
when the magnetostrictive layer 102 receives the mechanical strain from the piezoelectric
layer 104, the induced magnetisation oscillation in the high strain regions is lower
in magnitude than the induced magnetisation oscillation in the low strain regions.
In this way, an antenna radiation pattern is formed, consisting of regions of high
electromagnetic wave emission and regions of low electromagnetic wave emission. It
will be understood that the antenna radiation pattern can thereby be controlled by
control of the mechanical strain field generated by the one or more transducers 108,
for example by controlling or adjusting the magnitude or position of the regions of
high and low strain.
[0035] Furthermore, it follows that in receive mode, the regions of relatively high strain
are again difficult to excite, whereas the regions of relatively low strain are easier
to excite. Thus, when the H-components of a detected electromagnetic wave induces
an oscillating mechanical strain in the magnetostrictive layer 102, the magnetostrictive
layer will exhibit a greater response in low strain regions of the magnetostrictive
layer 102, and a lesser response in high strain regions of the magnetostrictive layer
102. In this way, by controlling or adjusting the magnitude or position of the regions
of high and low strain, the antenna 10 can be tuned to receive (i.e., detect) specific
frequencies of incoming electromagnetic waves.
[0036] The antenna element 100 illustrated in Figure 1 comprises a stacked arrangement of
a magnetostrictive layer 102 and a piezoelectric layer 104. In other examples, the
antenna element 100 may comprise a plurality of magnetostrictive layers 102 and/or
piezoelectric layers 104. In one advantageous example, the antenna element 100 may
comprise a single magnetostrictive layer 102 located, or sandwiched, between two piezoelectric
layers 104. In another advantageous example, the antenna element 100 may comprise
multiple magnetostrictive layer 102 and piezoelectric layer 104 pairs provided on
top of one another (i.e., a stack of alternating magnetostrictive and piezoelectric
layers). Such arrangements advantageously result in the production of a greater signal
magnitude, and hence greater device response in both the receive mode and transmit
mode.
[0037] In an example, the piezoelectric layer 104 comprises a memristive, memcapacitive
or complex memimpedance characteristic. The piezoelectric layer 104 may be formed
of, or comprise, a material having said characteristic. The entire piezoelectric layer
104 may have said characteristic, or a region of the piezoelectric layer 104 may be
formed having said characteristic. The piezoelectric layer 104 comprising said characteristic
is arranged to be set to a non-volatile condition by application of a voltage and/or
charge. Notably, the memristive material exhibits non-volatile memory characteristics
and continuous conductance change property, therefore making it suitable for use in
neuromorphic systems. A memristive material can be compared to a synapse in a brain.
[0038] The cellular mechanism that underlies learning and memory in human and animal brains
is called long-term potentiation (LTP). LTP is a persistent strengthening of synapses
based on recent patterns of activity. These are patterns of synaptic activity that
produce a long-lasting increase in signal transmission between two neurons. Short-term
potentiation (STP) refers to a process in which synaptic transmission is transiently
enhanced. In this manner, STP can be thought of as short-term memory. STP can change
into LTP through the process of repeated impressions involving many biological changes.
[0039] In general terms, a memristor (i.e., a memristive device) is a two-terminal resistive
switching device that can maintain its internal resistance states depending on the
history of applied voltages/currents. The two terminals behave similarly to an axon
and dendrite that connect pre-neurons and post-neurons of a synapse, with the conductance
of the switching layers comparable to the weight of the synapse. By changing the conductance
of the memristor to a set state, the device can be used to realise the memorisation
function of the human brain, by simulating the change from an unmemorised state to
the STP and LTP states.
[0040] The piezoelectric layer 104 may be set to a defined condition by application of a
voltage. Setting the piezoelectric layer 104 to the defined condition may comprise
varying a conductance of the piezoelectric layer 104 by application of the voltage
or charge. In particular, by applying a voltage to the piezoelectric layer 104, the
resistance, conductance, or complex impedance of the memristive material comprised
in the piezoelectric layer 104 can be modified, thereby realising the memorisation
function described above. The voltage to be applied to the piezoelectric layer 104
may be an external bias voltage/charge, or an internal charge produced by the antenna
10 due to the piezoelectric effect.
[0041] The condition (or state) of the piezoelectric layer 104 may depend on the prior state,
amplitude of the applied voltage, and acquisition time of the voltage/signal. For
example, after application of a first voltage, the condition of the piezoelectric
layer 104 may be changed from an initial state to a first state. If a second voltage
is applied to the piezoelectric layer 104 after the first voltage has been applied,
the condition of the piezoelectric layer 104 may be changed from the first state to
a second state.
[0042] The resistance, conductance, or complex impedance of the piezoelectric layer 104
may be varied based on at least one of a 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 comprised in the piezoelectric
layer 104 can be changed from an initial state to a higher state. Conversely, by applying
negative voltage pulses, the conductance of the memristive material 104 can be changed
from an initial state to a lower state. The conductance of the memristive material
may also be changed by modifying a duration of the applied voltage.
[0043] The piezoelectric layer 104 may be configured to retain the set condition after the
application of the voltage. As discussed above, a voltage may be applied in order
to change the conductance of the memristive material comprised in the piezoelectric
layer 104 can be changed from an initial state to a higher state. This change in conductance
of the memristive material is retained for a period of time after the application
of the voltage has ceased, thereby enabling the non-volatile memory operation of the
memristive material. In other words, there is no need for a constant voltage application
in order to vary the conductance of the memristive material in the piezoelectric layer
104. Varying the conductance/resistance of the memristive material comprised in the
piezoelectric layer 104 may change a resonant frequency of the antenna 10.
[0044] The retention time can be defined as the amount of time during which the piezoelectric
layer 104 will retain its set state, for example the amount of time during which the
memristive material comprised in the piezoelectric layer 104 will retain its conductance
at a changed state. The retention time may be increased by increasing at least one
of the number of voltage pulses, pulse width and/or pulse magnitude.
[0045] The piezoelectric layer 104 may be arranged to be set to the defined condition prior
to a receiving and/or transmitting operation of the antenna being performed. In such
way, the antenna 10 may be pre-programmed or pre-set to the defined condition.
[0046] As discussed above, strain is generated by the magnetostrictive layer 102 by converting
a magnetic field of a detected electromagnetic wave, i.e. the signal being detected
by the antenna 10. The piezoelectric layer 104 may be configured to produce the voltage
output based on a charge resulting from the received strain and the set condition
of the piezoelectric layer 104. As such, the voltage output produced by the piezoelectric
layer 104 may depend not only on the detected electromagnetic wave, but also on the
set condition of the piezoelectric layer 104. For example, the voltage output may
depend on the received strain, resulting from the detected electromagnetic wave, and
the modified conductance of the memristive material comprised in the piezoelectric
layer 104.
[0047] The piezoelectric layer 104 may be configured to produce the voltage output when
a charge resulting from the received strain is equal to a threshold value defined
based on the set condition of the piezoelectric layer. That is, the piezoelectric
layer 104 may be configured to produce the voltage output only at the pre-programmed
signal pattern acquisition. The piezoelectric layer 104 may be pre-programmed to respond
to a specific signal pattern by employing the memory capabilities of the memristive
material comprised therein. This can be realised by setting the piezoelectric layer
104 to the defined condition, corresponding to the signal pattern that a user wishes
to detect.
[0048] In detail, the process of signal recognition by the memristive material comprised
in the piezoelectric layer 104 may employ the switching nature of memristors. As discussed
above, by application of a voltage, the resistance, conductance and complex impedance
of the memristive material may be changed.
[0049] The transducer arrangement 108 comprises one or more waveguides 110. The one or more
waveguides 110 are operable to control the propagation of the mechanical strain field.
The operation of acoustic waveguides is well understood in the field of phononics.
Said waveguides 110 may be referred to as "phononic crystal waveguides". In the antenna
10, the waveguides 110 are operable to guide the input acoustic waves from the one
or more transducers 108 into the antenna element 100. Advantageously, this facilitates
control of the mechanical strain field propagation, as well as reducing loss of the
energy input to the antenna element 100.
[0050] The antenna 10 illustrated in Figure 1 and described above is shown and described
only to comprise a single antenna element 100. However, the antenna 10 may comprise
an antenna element array (or "antenna element matrix") comprising a plurality of antenna
elements. Such an arrangement is described below, with reference to Figure 2. It will
be appreciated that the operating principles of the antenna 10 will be understood
from the above description, with further features explained with reference to Figure
2.
[0051] Referring to Figure 2(a), a plan view of the antenna 10 comprising an antenna element
array 50 is shown. The antenna element array 50 comprises a plurality of antenna elements
100a, 100b, 100c, and so on. In the illustrated example, the antenna element array
50 comprises an array of laterally disposed antenna elements 100a, 100b, 100c (i.e.,
antenna elements arranged in a side-by-side manner). In another, non-illustrated,
example, the antenna element array 50 comprises an array of vertically disposed antenna
elements 100a, 100b, 100c (i.e., antenna elements arranged in a stacked or layered
manner). In an example, the antenna element array 50 may comprise a combination of
laterally and vertically disposed antenna elements. Providing the antenna element
array 50 is highly advantageous for a number of reasons. Generating a mechanical strain
field is more effective in smaller size antenna elements 100, which can be arranged
to build up a larger size antenna 10. A further benefit is that the antenna 10 can
be provided conformal to a platform surface, without antenna sensitivity to the surface
geometry of said platform. That is, curvature or edges in the platform provided with
the antenna 10 thereon will not impact operation of the antenna where the antenna
10 is formed of an array of (relatively small) antenna elements 100 arranged to form
a larger antenna 10.
[0052] In this example, the antenna element array 50 is a honeycomb antenna element array
of hexagonal shape antenna elements 100a, 100b, 100c. This shaping of antenna elements
100a, 100b, 100c in the antenna element array 50 is highly advantageous in packing
of the elements in the array (i.e., providing an arrangement having a high density
of antenna elements). Furthermore, the antenna 10 is not sensitive to the ground plane
and proximity effects between antenna elements. Therefore, close packing of many antenna
elements 100a, 100b, 100c is possible. Although hexagonal antenna elements provide
the highest packing ratio, it will be appreciated that other antenna element shapes
are of course possible, and indeed may be preferable or beneficial for operation of
the antenna 10 (e.g., generating a desired antenna radiation pattern or receiving
electromagnetic waves of a particular frequency).
[0053] Referring to Figure 2(b) and (c), an antenna element 100a of the antenna element
array 50 is shown in isolation, in plan and side cross sectional views respectively.
The magnetostrictive layer 102, piezoelectric layer 104, transducer 108 and a reflector
112 can be seen in Figure 2(c). Whilst not illustrated in Figures 2(b) and (c), the
transducer arrangement 106 also incorporates waveguides, as described above in relation
to Figure 1. A corresponding waveguide may be provided for each transducer.
[0054] A plurality of transducers 108a, 108b, 108c of the transducer arrangement 108 are
shown in Figure 2(b). The transducer arrangement 108, whilst present, is not illustrated
in Figure 2(a) for clarity.
[0055] The plurality of transducers 108a, 108b, 108c are operable to generate a mechanical
strain field in the antenna element 100a. Furthermore, by the principles of constructive
and destructive interference, the transducers 108a, 108b, 108c are operable to generate
a mechanical strain field interference pattern in the antenna element 100a. In this
way, regions of high strain (due to constructive interference) and regions of low
strain (due to destructive interference) can be generated in the magnetostrictive
layer 102.
[0056] As shown in Figure 2(b), one or more reflectors 112a, 112b, 112c are also provided.
The reflectors 112a - 112c are configured to reflect a mechanical strain wave generated
by the one or more transducers 108a - 108c. In this way, the reflectors 112a - 112c
may function to generate constructive and destructive interference of acoustic waves
(by reflecting the vibrations originating from the transducers), thereby to generate
the mechanical strain field interference pattern in the antenna element 100a. Furthermore,
reflectors 112a - 112c are highly advantageous in that they may allow the number of
transducers required to be reduced, thus reducing power consumption of the antenna
10.
[0057] In one example, one or more of the antenna elements 100a, 100b, 100c are provided
with one or more dedicated transducers. A dedicated transducer may be a transducer
which is arranged to generate a mechanical strain field in one particular antenna
element. In this way, in addressing the antenna element 100a of the array 50, the
dedicated transducer can be operated to generate a mechanical strain field in that
particular antenna element 100a. The situation may be similar throughout the array,
with each element 100a having one or more dedicated transducer. This is advantageous
in simplifying addressing of antenna elements, and enhances control over the mechanical
strain field generated.
[0058] In contrast, in another example, one or more transducers of the transducer arrangement
106 are operable to generate a mechanical strain field in a plurality of antenna elements
(for example 100a, 100b). In a specific example, the transducer 108a may be operable
to generate a mechanical strain field in antenna element 100a and neighbouring antenna
element 100c. Furthermore, the transducer 108b may be operable to generate a mechanical
strain field in antenna element 100a and neighbouring antenna element 100b. Advantageously,
by this construction, greater control over the mechanical strain field propagation
is provided. Additionally, and importantly, this simplifies construction and reduces
power consumption, although a more complex scheme may be required to address certain
antenna elements.
[0059] In a further non-illustrated example, an antenna arrangement may comprise two or
more antenna 10 stacked vertically (i.e., on top of one another). Advantageously,
this enables the possibility of having two or more beams serially aligned i.e., multiple
focal points. Such an arrangement facilitates depth sensing for each antenna element
stack.
[0060] In an exemplary application of the antenna 10, the antenna 10 may be operable to
detect an environmental characteristic (or environmental condition) in a region surrounding
the antenna element 100. The environmental characteristic may be a weather condition,
air moisture content, or the like. The transducer arrangement 106 is operable to generate
the mechanical strain field in the antenna element 100 based on the environmental
characteristic. The transducer arrangement 106 may be operable to generate the mechanical
strain field in the antenna element 100 to match a radar appearance of the region
surrounding the antenna element 100. That is, the antenna 10 operates to match a radar
appearance of the environment in which the antenna 10 is provided. The electromagnetic
signature of the antenna 10 may be changed in real-time to provide low observability
of the platform on which the antenna 10 is provided (such as a vehicle or structure),
in both stationary and moveable conditions. Each antenna element 100 may perform this
functionality, or alternatively the antenna 10 as a whole may do so.
[0061] Referring to Figure 3, a frequency selective surface 300 is shown. The frequency
selective surface 300 comprises the antenna 10. The transducer arrangement 106 is
operable to tune the frequency selective surface 300. Highly advantageously, the antenna
10 can be used as, or in, a frequency selective surface, and overcomes problems with
conventional frequency selective surfaces. In conventional frequency selective surfaces,
fixedly formed apertures or patches are provided across a surface, acting as a bandpass
or bandstop filter to a particular frequency of electromagnetic radiation. It will
be understood that conventional frequency selective surfaces have defined and non-adjustable
frequencies of interest. Instead, by the present construction, the antenna 10 enables
broad bandwidth control, by the control and adjustment of the mechanical strain field
by the transducer arrangement 106. Furthermore, the present construction provides
for beam steering capability. That is, control of the surface geometry of the antenna
10 allows control of the array resonance, absorption, transmission and reflection
properties of the antenna 10. Furthermore, controlled interaction with polarised electromagnetic
signals is facilitated.
[0062] Referring to Figure 4, a vehicle 400 is shown. The vehicle 400 comprises the antenna
10 or frequency selective surface 300. The antenna 10 or frequency selective surface
300 may be provided conformal to a surface of the vehicle 400. The vehicle 400 may
be an aircraft, watercraft, space craft (such as a satellite), and/or a road-going
vehicle.
[0063] Referring to Figure 5, a structure 500 is shown. The structure 500 comprises the
antenna 10 or frequency selective surface 300. The antenna or frequency selective
surface 300 may be provided conformal to a surface of the structure 500. The structure
500 may be a building and/or a construction.
[0064] Referring to Figure 6, a method of manufacturing an antenna 10 is shown. Step 610
comprises providing an antenna element comprising: a magnetostrictive layer; and a
piezoelectric layer, and a transducer arrangement comprising: one or more transducers
operable to generate a mechanical strain field in the antenna element to produce displacement
of the surface of the magnetostrictive layer.
1. An antenna (10) comprising:
an antenna element (100) comprising:
a magnetostrictive layer (102); and
a piezoelectric layer (104),
wherein the antenna further comprises a transducer arrangement (106) comprising:
one or more transducers (108) operable to generate a mechanical strain field in the
antenna element (100) to produce displacement of the surface of the magnetostrictive
layer (102).
2. The antenna (10) according to claim 1, wherein, in a receive mode, the magnetostrictive
layer (102) is configured to convert a magnetic field of a detected electromagnetic
wave into mechanical strain, and the piezoelectric layer (104) is configured to receive
the mechanical strain from the magnetostrictive layer and produce a voltage and/or
charge output based thereon.
3. The antenna according to claim 1 or claim 2, wherein, in a transmit mode, the piezoelectric
layer (104) is configured to receive a voltage and/or charge input and produce mechanical
strain based thereon, and the magnetostrictive layer (102) is configured to receive
the mechanical strain produced by the piezoelectric layer to produce and output an
electromagnetic wave based thereon.
4. . The antenna according to claim 3, wherein the antenna element (100) is operable
to detect an environmental characteristic in a region surrounding the antenna element,
and the transducer arrangement is operable to generate the mechanical strain field
in the antenna element based on the environmental characteristic.
5. The antenna according to any one of the preceding claims, wherein the piezoelectric
layer (104) comprises a memristive, memcapacitive or complex memimpedance characteristic,
optionally wherein the piezoelectric layer is arranged to be set to a defined non-volatile
condition by application of a voltage and/or charge.
6. The antenna according to any one of the preceding claims, wherein the transducer arrangement
comprises a plurality of transducers (108a, 108b, 108c) operable to generate a mechanical
strain field interference pattern in the antenna element.
7. The antenna according to any one of the preceding claims, wherein the transducer arrangement
comprises one or more waveguides (110).
8. The antenna according to any one of the preceding claims, comprising an antenna element
array comprising a plurality of antenna elements (100a, 100b, 100c).
9. The antenna according to claim 7, wherein the antenna element array is a honeycomb
antenna element array of hexagonal shape antenna elements.
10. The antenna according to claim 7 or claim 8, wherein one or more antenna elements
are provided with one or more dedicated transducers.
11. The antenna according to any one of claims 7 to claim 9, wherein one or more transducers
of the transducer arrangement are operable to generate a mechanical strain field in
a plurality of antenna elements.
12. The antenna according to any one of the preceding claims, wherein the antenna further
comprises one or more reflectors (112) configured to reflect a mechanical strain wave
generated by the one or more transducers.
13. A frequency selective surface (300) comprising the antenna (10) as claimed in any
one of the preceding claims, optionally wherein the transducer arrangement (106) is
operable to tune the frequency selective surface.
14. A vehicle (400) or structure (500) comprising the antenna (10) according to any one
of claim 1 to claim 12 or a frequency selective surface (300) according to claim 13.
15. A method of manufacturing an antenna (10), comprising providing:
an antenna element (100) comprising:
a magnetostrictive layer (102); and
a piezoelectric layer (104), and
a transducer arrangement (106) comprising:
one or more transducers (108) operable to generate a mechanical strain field in the
antenna element (100) to produce displacement of the surface of the magnetostrictive
layer (102).