GB2455749A

GB2455749A - Antenna using piezoelectric material

Info

Publication number: GB2455749A
Application number: GB0724788A
Authority: GB
Inventors: Dhiraj Sinha
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-12-20
Filing date: 2007-12-20
Publication date: 2009-06-24
Also published as: GB0823156D0; GB0724788D0

Abstract

A method of transmitting or receiving electromagnetic waves comprises the acceleration of charges within a piezoelectric material 1. The interaction between the mechanical and electrical forces when a varying electric or electromagnetic signal is applied to the piezoelectric material 1 provides an enhanced and efficient transmission or reception signal, respectively. Various piezoelectric materials may be used in stacked layers. The antenna may include filter and/or impedance matching arrangements. Electrical and/or mechanical adjustments may be made to the antenna to modify its operational characteristics. Alternatively, the piezoelectric material may be replaced by an electrostrictive or magnetostrictive material. The antenna may be used in compact communication devices such as mobile phones and computers or in radio frequency identification RFID systems.

Description

Title: Miniaturised Antenna

References Cited

Patents Brit. Patent 12039 1896 G. Marconi U.S. Patent 645576 3/1 900 N. Tesla U.S. Patent 725605 4/1 903 N. Tesla U.S. Patent 755840 3/1904 J.C. Bose French Patent 505703 1921 P. Langevin U.S. Patent 1450246 1923 W.G. Cady U.S. Patent 6462464 10/2002 S. Mitarai U.S. Patent 7207222 4/2007 Thompson et al. Other References 1. H.R. Hertz, Annalen der Physik und Chemie 34, 155-171, (1888).

2. J. C. Bose, Proc. Royal Society, LXV, 416, 166-172, (1899).

3. (3. Marconi, Electrician, 358-392, (1902).

4. Weigel et. al., IEEE Transactions on Microwave Theory and Techniques, 50, 738- 749, (2002)

SUMMARY

The present invention is on a means of transmission and reception of electromagnetic waves using piezoelectric materials. A piece of piezoelectric material subjected to time-varying wired electrical excitation results in acceleration of charges within the material which eventually results in electromagnetic radiation from the material. When electromagnetic waves propagating through free space hit a piezoelectric material, the electrical charges within the material are accelerated resulting in a flow of current and generation of voltages in the material and it acts as a receiving antenna. The high quality factors associated with resonant modes of the piezoelectric crystals imply that they can be used in place of normal antennas as transmitter and receivers of electromagnetic waves for telecommunication and related applications.

FIELD OF INVENTION

The present invention is on a method of transmission and reception of electromagnetic waves using piezoelectric materials mainly for wireless telecommunication applications.

BACKGROUND OF THE INVENTION

Wireless radio communication started with the work of Hertz (Hertz, 1888), Bose (U.S. Patent 755840), Marconi (Brit. Patent 12039) and Tesla (U.S. Patent 645576, U.s.

Patent 725605). Over the past hundred years, the basic principle of radio signal detection by antennas has remained the same. A thin wire structure receives an electromagnetic wave under electrical resonance, which implies that the antenna length must be comparable to the wavelength of the radio signal. This has posed a fundamental challenge behind scaling down of antenna size and their integration on an electronic chip and antenna technology has remained practically untouched by the advances in nanotechnology.

A piezoelectric resonator is an elastic solid body consisting of a piezoelectric crystalline material which can be excited to mechanical resonance under an electric field. As the crystal vibrates, the periodic deformation causes periodic piezoelectric charges on the metallic electrodes linked to it. The sharp resonant frequencies of piezoelectric resonators are of great commercial interest. The earliest work on piezoelectric resonators was done by Langevin who patented the first device on transmitter and receiver of elastic waves in water for submarine applications (French Patent 505703). The vibrating piezoelectric resonator also has an effect on the circuit to which it is connected. This was first observed by Cady who applied it to develop a device as a standard of frequency, a filter and as a coupling device between circuits (U.S. Patent 1,450,246). Over the years, piezoelectric devices have been widely used in acoustic sensing, oscillators and filters and related applications (Weigel et. al., 2002).

Recently, wireless radio frequency excitation of piezoelectric crystals have been investigated particularly in biological detection experiments (U.S. Patent 7207222).

Such a technology does not need the electrodes on piezoelectric crystals in order to measure the changes in resonance frequencies.

One important objective of the present invention is to develop a microantenna based on wireless radio frequency effects associated with a piezoelectric material which would lead to development of miniaturised antennas.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a piezoelectric stack connected to a signal generator.

Figure 2 shows a series RLC circuit as a model of a piezoelectric material.

Figure 3 shows the molecular layout of a typical piezoelectric material.

Figure 4 shows the internal structural details of multilayered a piezoelectric stack.

Figure 5 shows an experimental set up for detecting wireless radio frequency signal using a piezoelectnc material.

Figure 6 shows a piezoelectric material in the form of a beam.

*Figure 7 shows a surface mounted bulk acoustic resonator.

Figure 8 shows a typical result of a piezoelectric material as a transmitter.

Figure 9 shows a typical result of a piezoelectric material as a receiver.

Figure 10 shows a surface acoustic wave resonator as a transmitter.

Figure 11 shows a surface acoustic wave resonator as a receiver.

Figure 12 shows a typical result of a surface acoustic wave resonator as a transmitter.

Figure 13 shows a typical result of a surface acoustic wave resonator as a receiver.

Figure 14 shows an impedance matching circuit.

DETAILED DESCRIPTION

A piezoelectric material is electrically polarised under the application of a static electric field. This leads to mechanical deflection within the material and stress. When an alternating electric field is applied to a piezoelectric material, bulk and surface acoustic waves are set up in the material due to a change in the direction of electrical polarisation and the direction of mechanical stresses associated with it. The acceleration of charges in the material associated with time varying electrical excitation leads to radiation of electromagnetic waves in space. The surface and bulk acoustic waves enhance the acceleration of charges within the material leading to an enhanced emission of electromagnetic radiation in free space because of interplay between the electrical and mechanical forces.

The amplitude of vibration of the piezoelectric material and the transmitted electromagnetic wave become high under a resonance between its surface or bulk acoustic modes and the modes of the wired time-varying electrical excitation applied to it. As the quality factor of piezoelectric crystals can be very high, a very efficient transmitting antenna can be developed using such crystals.

Figure 1 shows such a piece of piezoelectric material 1 with electrodes 2 and 3 connected to a voltage source 4 for wired electrical excitation. Application of a time varying voltage to the electrodes 2 and 3 would result in an electric field across the material, which would lead to generation of an acoustic wave within the piezoelectric stack. For low frequency electric fields (< 10 KHz), the charges within the piezoelectnc stack are accelerated and there is a displacement current between the electrodes. This leads to generation of electromagnetic waves. The physics of the system undergoes some change when the frequency of excitation is raised to a relatively higher value.

The mechanism of radiation from a piezoelectric material would become evident if we look at its electrical equivalent circuit presented in figure 2 which shows a series resistance R, a capacitor C, an inductor L in parallel to a capacitor Cj. At low frequencies of excitation, the capacitive elements dominate and the system behaves as a reactive load. Application of a low frequency voltage leads to generation of a displacement current within the piezoelectnc stack. However, at high frequencies, the reactive impedance becomes dominant and the system behaves as an inductor. This can also be called a lossy capacitor. As a result of it, conduction current flows across the piezoelectric material for high frequencies leading to an enhancement in electromagnetic radiation.

We can define the variation of electrical polarisation with mechanical stress in a piezoelectric material as piezoelectric strain constant of the device. Thus, (1)

S

P is the polarisation and S is the mechanical stress. The unit of 8 is metre/volt and it is the primary physical quantity of interest in terms of selection of a piezoelectric material for sensor based applications. Each type of ceramic has a unique piezoelectric strain constant that allows calculation of physical distortion upon the application of a potential. A typical value of piezoelectric strain constant could be I nm/volt. Hundreds of layers of such piezoelectric material can augment the net displacement. The total displacement of such a stacked structure can be defined as d=nöV (2) where d is deflection, n is the number of layers and 8 V is the voltage applied across the top and the bottom layers of the piezoelectric stack. The displacement changes its direction with the polarity of the applied voltage. This is because of a lack of a centre of symmetry in the molecular structure of a piezoelectric material as shown in Figure 3, where an application of compressive force in the horizontal direction results in decrease in the angle 9 and development of polarization along the downward direction. A tensile force along the horizontal direction results in an increase in the angle 9 and development of polarization along the upward direction. The dashed lines of figure 3 show an asymmetrical configuration of charges which is the origin of the piezoelectric phenomenon.

Figure 4 shows the internal structure of a multilayered piezoelectric stack especially designed to raise its strain voltage ratio. Its construction has been described in detail in U.S. Patent 6462464. It has a number of piezoelectric layers 5 each having a thickness of several microns all glued together to from a compact piezoelectric stack.

Each layer has metallic layers 6 and 7 having a thickness of a few microns deposited on both the sides. There could be a total of 624 such layers on a stack of 18 mm height each of 20 micron thickness with each layer covered by a 2 micron thick metallic layer.

There are side metallic layers 8 on the sidewalls of the piezoelectric stack which form as an interface between external wires and the internal piezoelectric material. The thickness of the side metallic layer 8 is around 10 micron which is used to excite all the layers 9 together. The side metallic layers 8 are connected to an internal layer, which is a metallic resin which can be displaced mechanically without causing any stress to the metallic layer.

The metallic leads on the sides of the piezoelectric stack and the plurality of metallic layers on the top and bottom side of the piezoelectric material act as a number of capacitors 11 as shown in figure 4. During the time-varying electrical excitation of the piezoelectric stack, as the frequency crosses a certain value, the capacitors act as short circuit and the whole structure acts as a loop, which results in conduction current due to the flow of charges across the whole structure resulting in radiation. In the receiving mode, at such frequencies, a change of flux across the loop leads to generation of a pulsating potential within the stack under electromagnetic field excitation which builds up under resonance.

In case of a single layered piezoelectric material, similar effects happens above a certain frequency. The capacitive reactance transforms into an inductive reactance leading to enhanced emission and reception of electromagnetic waves.

A piezoelectric material as a receiver is shown in figure 5. An RF coil 12 excited by a signal generator 13, generates an RF magnetic field which is picked up by the piezoelectric stack 14. The signal can be observed on a spectrum analyser 15. At low frequencies, the system can generate only magnetic fields but as the frequency increases, the electric field of the electromagnetic wave can be easily detected.

An incoming electromagnetic wave interacts with the bound charges of a piezoelectric material. This results in acceleration of the charges and periodic change in the electrical polarisation of the material. This results in the generation of an acoustic wave within the material leading to an enhanced acceleration of charges within the material because of an interplay between electrical and mechanical forces, resulting in an enhanced displacement current which induces a relatively higher degree of voltage in the piezoelectric material.

The amplitude of acoustic modes and electromagnetic modes can be raised when their frequencies match the frequencies of a wireless electromagnetic wave propagating in free space. Thus the system can act as a very good electromagnetic wave receiver or a receiving antenna. If the frequency of the incoming wave is above a certain frequency, the acceleration of the bound charges would lead to a conduction current within the material leading to an enhanced radiation.

A related aspect of the invention is use of a free standing piezoelectric material sandwiched between two electrodes as shown in figure 6. 16 is a semiconductor substrate over which the free standing beam 17 is developed with electrodes 18. The whole structure is supported by the edge of the substrate 16. Under the application of an electric field, the vibrations are generated within the beam 17. This necessitates the development of an air gap which is accomplished by first depositing and patterning an area of support material followed by deposition and patterning of the piezoelectric material along with the electrodes and finally etching the sacrificial material. Wet etching and plasma etching are found to be excellent for the development of resonators.

Such devices are called Film Bulk Acoustic Wave (FBAW) resonators. The embodiment of figure 6 can be modified to encompass other structures like cantilevers, bridges and related free standing structures having flexural or torsional modes of vibrations.

One problem with resonators is dissipation of acoustic energy within the substrate. Solidly mounted resonators can be used to reduce the reflection related losses in such devices. Figure 7 shows one such embodiment where the piezoelectric membrane 19 with the electrodes 20 is isolated from the substrate 16 with a reflector anay composed of layers 21 having quarter wavelength thickness.

Figure 8 shows a signal of amplitude 79.71 my received by a multilayered piczoelectric stack of dimensions 2mmx5mmx5mm from a 5 turn copper coil of radius of 2 cm placed at a distance of 20 cm from it. The coil is excited at 48 MHz and 1 V, generating a magnetic field of 1.48 nanotesla along the coil's axis and a circulating electric field of4l mv/rn along the plane of the RF coil.

The piezoelectric stack can also be used as a transmitter. If the same stack is excited at 48 MHz and IV, the voltage induced in a copper coil of 5 turns and 2 cm radius, placed at a distance of 20 cm from it is 19.0 my as shown in figure 9. The magnetic field is 10.02 nanotesla which is comparable to that of a simple RF coil of radius 2 cm.

The results obtained for a stack of piezoelectric material also hold for surface acoustic wave (SAW) based devices with interdigital electrodes developed over the piezoelectric surface. Figure 10 shows one such device where the piezoelectric substrate 20 has electrodes 23 and 24 having fingers which are interleaved and excite surface waves under the application of voltage from a source 22.

Such a device can act as a receiver as shown in figure 11 where a resistive load is connected to the SAW based device. The input electromagnetic wave excites SAW waves on the piezoelectric material, which travel to the other end of the electrodes and develops a voltage.

Figure 12 shows a signal of voltage 2.91 my received by a SAW device of dimensions 2mmx5mm from a copper coil of 5 number of turns and a radius of 2 cm, placed at a distance of 20 cm from it. The RF coil is excited at 61 MHz and IV, generating a magnetic field of the order of 0. 47 nanotesla along its axis and a circulating electric field of 18.1 mv/rn along the plane of the RF coil.

The SAW device can also be used as a transmitter. If it is excited at 61 MHz and 1V, the voltage induced in a copper coil of 5 turns and 2 cm radius, placed at a distance of 20 cm from it is 1.46 my as shown in figure 13. The magnetic field is 0.60 nanotesla which is comparable to that of a simple RF coil of radius 2 cm.

Above a certain frequency, the piezoelectric material acts as a sum of resistive and inductive element. This has been shown in figure 14 where 26 and 27 are the resistive and inductive elements associated with the piezoelectric material respectively.

28 is an external capacitor connected in series to the piezoelectric material and 29 is an external inductor connected in shunt to the piezoelectric material to match the total impedance of the system to free space. This impedance matching raises the total sensitivity. The values of the circuit elements are taken into account by doing proper calculations as per the prior art in this field. The products of impedances of series and shunt elements (capacitve or inductive) should be equal to the product of impedances of I0 load and the signal generator in the transmission mode and free space in the reception mode. A resonant circuit having very good quality factor can also be used instead of 18 and 19 or along with it.

An alternative way of impedance matching would be to use a section of line of length A14, ? where is the wavelength, whose impedance equals the product of load and source impedances. Yet another way of impedance matching would be to make use of the Smith Chart Adding a coil to the piezoelectric material would raise the total area, the flux collecting ability and the sensitivity of the system. The sensitivity of the device can also be raised by quality factor improvement. The device can be enclosed in vacuum in order to achieve this. An alternative method would be to compensate the mechanical losses during the vibration by an electrical circuit which would compensate for the losses by applying an electrical signal depending on the resonance frequency and phase of the vibration frequency.

The resonance frequency of the piezoelectric material can be changed by applying a DC bias or by mechanical loading of the device.

The results shown in figures 7,8, 11 and 12 are for transmission and reception for the near field region of an antenna, however, the piezoelectric stacks and SAW devices can receive signals if they are situated in the far field region of an

electromagnetic field.

The electromagnetic waves received by a piezoelectric device can be connected to or integrated with the electronic circuit of telecommunication equipment like television, mobile, radio receiving set and computers. The piezoelectric device can also act as transmitter in telecommunication applications. Another interesting application of such devices can be in radio frequency identification tags.

As surface or bulk acoustic wave devices are widely used as filters in telecommunication applications, the present device can be used simultaneously as an antenna and a filter.

The piezoelectric material can be replaced by an electrostricitve material or a magnetostricitive material and the results disclosed might be used in a similar fashion.

In case of an electrostrictive material, the wired electrical excitation applied to it will result in acceleration of charges and emission of radiation in a similar fashion. The efficiency will be slightly low as the acoustic waves would not influence the acceleration of the charges. In case of receiving mode, the electromagnetic wave will accelerate the charges and create voltage within the material.

The piezoelectric material can be replaced by a magnetostrictive material for transmission and reception of signals. The magnetic field associated with wired time varying electrical excitation will excite the magnetic moments within the magnetostrictive materials resulting in emission of radiation. In the receiving mode, the magnetic field of the electromagnetic wave will excite the magnetic moments eventually leading to generation of voltage within the material due to a change in magnetic flux.

Claims

What is claimed is: 1. A method of transmission of electromagnetic waves by piezoelectric materials where the wired time varying electrical excitation applied to a piezoelectric material results in acceleration of charges within the material leading to emission of electromagnetic radiation in free space; a method of reception of electromagnetic waves propagating through free space by piezoelectric materials where the electromagnetic waves hitting the piezoelectric material accelerate the charges within the material resulting in displacement current which induces voltage in the piezoelectric material.
2. A method of transmission of electromagnetic waves in accordance with claim 1 where the capacitive reactance of the piezoelectric material of claim 1 behaves as an inductive reactance above a certain frequency of time-varying wired electrical excitation resulting in flow of time-varying conduction current causing relatively higher degree of electron acceleration eventually leading to a higher degree of emission of electromagnetic radiation; a method of reception of electromagnetic waves in accordance with claim I where the capacitive reactance of the piezoelectric material of claim I behaves as an inductive reactance above a certain frequency of wireless electromagnetic excitation resulting in flow of time-varying conduction current causing relatively higher degree of electron acceleration within the piezoelectric device leading to development of a higher degree of voltage across the electrodes eventually leading to enhanced reception of electromagnetic radiation.
3. The method of transmission of electromagnetic energy in accordance with claims 1 and 2 where the wired time varying electrical excitation applied to a piezoelectric material results in acceleration of charges within the material leading to mechanical vibrations causing the propagation of bulk and/or surface acoustic waves within the material which further enhance the acceleration of charges within the material leading to an enhanced emission of electromagnetic radiation in free space because of an interplay between the electrical and mechanical forces; a method of reception of electromagnetic waves propagating through free space where the electromagnetic waves hitting the piezoelectric material results in acceleration of charges within the material causing mechanical vibrations and propagation of bulk and surface acoustic waves within the material leading to an enhanced acceleration of the charges within the material because of an interplay of electrical and mechanical forces, resulting in an enhanced displacement current which induces a relatively higher degree of voltage in the piezoelectric material.
4. The method of transmission in accordance with claims 1,2 and 3 where the amplitude of vibration of the piezoelectric material and the transmitted electromagnetic wave become high under a resonance between the its surface or bulk acoustic modes and the modes of the wired time- varying electrical excitation applied to it; a method of reception of electromagnetic waves in accordance with claim 1, 2 and 3 where the amplitude of vibration of the piezoelectric material and the received signal become high under a resonance between its surface or bulk acoustic frequencies and the frequencies of wireless electromagnetic wave hitting the piezoelectric material.
5. The method of transmission and reception of electromagnetic waves in accordance with claims 1,2 and 3 where the piezoelectric material of claim 1 has got metallic layers on top and bottom permitting electrical excitation in the transmission mode and permitting collection of voltage in the reception mode.
6. The method of transmission of electromagnetic waves in accordance with claims 1,2 and 3 where the piezoelectric material of claim I has got a plurality of thin layers of piezoelectric materials all stacked on top of each other with metallic layers along the top and bottom layers all connected to different electrodes permitting a higher degree of voltage displacement ratio under time-varying wired electrical excitation resulting in a higher degree acceleration of charges, mechanical vibrations and electromagnetic radiation in proportion to the number of layers; the method of reception of electromagnetic waves in accordance with claims 1,2 and 3 where the piezoelectric material of claim 1 has got a plurality of thin layers of piezoelectric materials all stacked on top of each other with metallic layers along the top and bottom layers all connected to different electrodes permitting voltage collection under wireless electromagnetic wave excitation which causes a higher degree acceleration of charges, mechanical vibrations and voltage induction in proportion to the number of layers.
7. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where the piezoelectric material of claim 1 are free standing structures having distinct resonance modes; where the freestanding structures imply membranes, beams or bridges or a cantilevers vibrating in compressional (alternatively called longitudinal or extensional), shear (alternatively called transverse), torsional and/or fiexural modes of vibrations.
8. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where the piezoelectric material of claim 1 is developed over a substrate and is isolated from the substrate with a reflector array composed of layers having quarter wavelength thickness.
9. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where a thin film of piezoelectric material has got interleaved electrodes all alternately connected to positive and negative electrodes permitting application of wired voltage excitation resulting in acceleration of electrons and generation of surface acoustic waves and subsequent electromagnetic radiation in the transmission mode and permitting collection of induced voltages caused by electron acceleration and generation of surface acoustic waves from the incoming electromagnetic wave in the reception mode.
10. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where the resonant frequency of the piezoelectric material is changed by applying a static voltage to it.
11. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where the resonant frequency of the piezoelectric material is changed by mechanically loading it.
12. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where a metallic loop is connected to the piezoelectric material of claims 1, 6 and 7 in order to raise the total area of electric flux linkage and hence the sensitivity of the transmission and reception of electromagnetic waves method ofclaiml.
13. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where the impedance of the piezoelectric material is matched to the wired electrical excitation generator using an impedance matching circuit comprising a set of shunt (or series) inductors and a set of series (or shunt) capacitors in such a manner that the products of impedances of wired electrical excitation generator and piezoelectric material match the products of the impedances of series (or shunt) capacitors and shunt (or series) and inductors; method of reception of electromagnetic waves in accordance with claims I and 2 where the impedance of the piezoelectric material is matched to that of free space using an impedance matching circuit comprising a set of shunt (or series) inductors and a set of series (or shunt) capacitors in such a manner that the products of space and piezoelectric impedances match the products of the impedances of series (or shunt) capacitors and shunt (or series) and inductors.
14. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where the impedance of the piezoelectric material is matched to that of free space or the signal generator by using a section of line of length X/4, where where is the wavelength such that the impedance of the line equals the square root of the product of the piezoelectric material impedance and the impedance of signal generator or free space.
15. The method of transmission and reception of electromagnetic waves in accordance with claims 1, 2 and 3 where the impedance of the piezoelectric material is matched to that of free space or the signal generator by using a series capacitive or reactive element or shunt reactive or capacitive element whose values and locations are read out using a Smith Chart.
16. Enclosing the piezoelectric material of claim 1, 2 and 3 in vacuum to raise the sensitivity of the method of transmission and reception of electromagnetic waves of claims 1.
17. Use of an electronic circuit in feedback mode to feeds in electrical energy to the piezoelectric stack of claim I periodically by proper match of phase and

S

frequency in order to compensate the loss of damping linked to the vibrations of piezoelectric material of claim I and thereby raising the quality factor and sensitivity of the method of transmission and reception of electromagnetic waves of claims 1, 2 and 3.
18. Method of transmission of electromagnetic waves in accordance with claims 1, 2 and 3 where the piezoelectric material is connected to or integrated with the electronic components of a communication device like a radio or television transmitter, a computer, a radio frequency identification tag or a related device which uses an antenna for transmitting signals; method of reception of electromagnetic waves in accordance with claim I and 2 where the piezoelectric material is connected to or integrated with the electronic components of a communication device like a television, mobile hand set, radio receiving set, computer, a radio frequency identification tag or a related equipment.
19. Method of transmission of electromagnetic waves in accordance with claims 1, 2, 3 and 4 where the objective of filtering of a signal is realised simultaneously alongside the method of transmission and reception of electromagnetic waves.
20. The method of transmission and detection in accordance with claim 1 where the piezoelectric material is replaced by a material having electrostrictive properties.
21. The method of transmission in accordance with claim 1 where the piezoelectric material is replaced by a material having magnetostrictive properties and the magnetic field associated with wired time varying electrical excitation excites the magnetic moments within the magnetostrictive materials resulting in emission of electromagnetic radiation; a method of reception of electromagnetic waves in accordance with claim I where the magnetic field of the electromagnetic wave excites the magnetic moments in the magnetostrictive materails eventually leading to generation of voltage within the material due to a change in magnetic flux.