The present invention concerns a device for receiving and/or emitting an electromagnetic wave, a system comprising said device, and a use of such device.
It is known from the applicant's own patent application WO 2008/007024, a device having a reactive type antenna element surrounded by a plurality of metallic diffusers. Thanks to this arrangement, the electromagnetic wave is focused to a point i near the antenna element at a sub wavelength distance.
This device is efficient, but still need to be improved.
One object of the present invention is to provide an improved device for receiving and/or emitting an electromagnetic wave.
To this effect, the device proposes a device for receiving and/or emitting an electromagnetic wave having a free space wavelength λ0 comprised between 1 mm and 1 m, comprising:
Thanks to these features, the device comprises a tuned conductor element having an electromagnetic resonance in coincidence to a transverse electromagnetic mode (TEM) of the medium incorporating said conductor elements (a wire medium). The device is therefore able to receive or emit efficiently an electromagnetic wave, and such device is extremely compact in size. It is compact in size along transversal or lateral directions X, Y perpendicular to the direction D.
In various embodiments of the device, one and/or other of the following features may optionally be incorporated:-a plurality of transverse electromagnetic modes inside the medium have electric and magnetic vectors extending along said first surface, and have a propagation vector extending along the direction, and the plurality of transverse electromagnetic modes have a medium resonance frequency corresponding to said wavelength λ;
Another object of the present invention is to provide a system comprising a device for receiving and/or emitting an electromagnetic wave, wherein the antenna element is connected to an electronic device for receiving and/or emitting an electric signal representative to said electromagnetic wave.
Another object of the present invention is to use a device for receiving and/or emitting an electromagnetic wave having a free space wavelength λ comprised between 1 mm and 1 m, and preferably between 10 cm and 40 cm.
Other features and advantages of the invention will be apparent from the following detailed description of six of its embodiments given by way of non-limiting example, with reference to the accompanying drawings.
In the drawings:
a, 2b and 2c are three views of three transverse electromagnetic modes inside the device of
In the various figures, the same reference numbers indicate identical or similar elements. The direction Z is a vertical direction. A direction X or Y is an horizontal direction.
The
This device comprises:
The medium has a refractive index nd.
The space may be air and is considered to have a refractive index equal to one.
The free space wavelength λ0 corresponds to a wavelength λ inside the medium 11 with the following relation: nd·λ=λ0.
The medium 11 has a parallelepiped shape, comprising a first surface S1 and a second surface S2, opposite to said first surface along the vertical direction Z. The first and second surfaces S1, S2 are substantially parallel planes. A direction D is substantially a straight line perpendicular to said surfaces and parallel to the vertical direction Z. The first and second surfaces S1, S2 are distant of a height value H.
The medium has an electric permeability of εd.
The conductor elements 12 are circular wires of diameter and extending along said direction D. These conductor elements 12 have a first end 12a on said first surface S1 and a second end 12b on said second surface S2. Each conductor element 12 has a length of the same value H. In this first embodiment the conductor elements 12 form on the first surface S1 or any plane XY perpendicular to said vertical direction Z a regularly spaced square grid. The conductor elements 12 are parallel to each other along the vertical direction Z and are spaced from each other along the direction X or Y of a distance d lower than λ/10. This sub-wavelength distance d is the step of said grid. The conductor elements 12 form therefore a regular lattice of wires.
One or several antenna elements 13 are installed on said first surface S1 or said second surface S2 or both of them. The antenna elements 13 may be fed with a single electric signal S to emit or receive a single electromagnetic wave W, or they may be fed with a plurality of electric signals to emit or receive simultaneously a plurality of electromagnetic waves.
In such wire medium comprising wire conductor elements 12 embedded inside a medium 11, the magnetic field vector B and the electric field vector E are perpendicular to said direction D, and the propagation wave vector K is a propagation vector collinear to said direction D. The electromagnetic wave W is a plane wave propagating inside the medium 11 along the direction D.
The magnetic field vector B and electric field vector E have transverse electromagnetic modes TEM inside said medium 11, with nodes and antinodes. These TEM modes have sub-wavelengths variations along directions X and Y.
The wire medium is a non dispersive medium and the dispersion relation is:
ω=kz·c/nd,
where:
kz is the Z component value of the propagation wave vector K,
c is the electromagnetic wave speed in vacuum,
nd is the refractive index of the medium material.
For example, the refractive index of air is 1 and the refractive index of epoxy is around 2.
The medium 11 is therefore an anisotropic medium. Each TEM mode has the same propagation speed and the same resonance frequency f, f=ω/(2·π).
All or part of the conductor elements 12 of the medium 11 can be tuned to this resonance frequency f. The conductor elements 12 may have a specific length Hwire between 0.7·N·λ/2 and N·λ/2, where:
More precisely, the conductor elements 12 may have a specific length Hwire of:
Hwire=N·λ/2.
The tuned conductor elements 12 have therefore a resonance frequency in coincidence with the resonance frequency of the TEM modes.
Thanks to this tuning, the TEM modes may excite or may be excited by most of the conductor elements 12 incorporated inside the medium 11.
Advantageously, the antenna element 13 may be positioned proximal to at least one antinode of the transverse electromagnetic modes of the medium 11. This may improve the device sensivity to receive and/or emit the electromagnetic wave.
A plurality of antenna elements 13 may be implemented inside the device. Each antenna element 13 of this plurality may be positioned proximal to a different antinode of the transverse electromagnetic modes TEM. Each antenna element 13 is then fed with a single electric signal S. Then, a plurality of modes belonging to the TEM modes are excited and more conductor elements 12 contribute to receive and/or emit the electromagnetic wave W. By this way, the radiation diagram of the device may be affected.
A plurality of antenna elements 13 may be implemented inside the device. Each antenna element 13 of this plurality may be positioned proximal to a different antinode of the transverse electromagnetic modes TEM. Each antenna element 13 may be fed with a different electric signal S. By this way, the device can receive and/or emit a different and independent electromagnetic waves W, simultaneously.
In a first variant, the antenna element 13 may be simply one of the conductor elements 12 of the wire media that is connected to the electronic device 14.
In a second variant, the antenna element 13 is a conductor patch or wire above an electronic board, said electronic board being in close proximity with the first surface S1 and/or second surface of the medium 11.
In various embodiments, it is possible to generate inside said medium TEM modes with different resonant frequencies.
In a second embodiment shown on
In a third embodiment shown on
In a fourth embodiment shown on
In a fifth embodiment shown on
In a sixth embodiment shown on
Moreover, contrary to the previous embodiments, the conductor elements 12 do not form a periodic pattern along the first surface S1.
Thanks to the five previous various embodiments, the medium 11 comprises several resonant frequencies and the device for receiving or emitting an electromagnetic wave may have an enlarged bandwidth.
Additionally and according more variants:
The present invention device 10 may be manufactured by known methods. For example, multilayer copper etching above epoxy material may be used, each layer comprising a plurality of conductor elements inside the plane of the layer.
In all the embodiments of the invention, illustrated in
A loop conductor element is an electric inductance.
Such loop conductor element can be associated with a capacitive element to behave as an electric LC resonator, receiving or emitting a magnetic field.
In such case, an ends distance between the first and second ends belonging to a conductor element 12 is lower than λ/10.
Such conductor element 12 forming a loop, is often called a split ring element, or a capacitively loaded loop, or an artificial magnetic conductor.
A device for receiving and/or emitting an electromagnetic wave using such electric loops is generally flat, and generally has a large size in the transversal or lateral directions X, Y.
The conductor elements 12 of present patent application do not have such global electric behaviour. The conductor elements 12 are mainly linear wires that may be arched. They have an electromagnetic resonance along their length, receiving or emitting an electric field.
The conductor elements 12 are not forming a loop adapted to generate a magnetic field oscillating at the wavelength λ.
As represented on
The first and second ends are distant. Contrary to a loop conductor, the conductor elements 12 do not create a significant electric capacitive effect.
The conductor element 12 has a form so that: if first and second points P1, P2 belonging to said conductor element 12 are distant from each other of a curvilinear distance along the conductor element 12 higher than λ/2 or λ/4, then a straight line distance between said first and second points is higher than λ/10.
A portion of the conductor element 12 between first and second points P1, P2 do not form a loop. Contrary to a loop conductor, the conductor elements 12 do not create a significant electric inductive effect.
The conductor elements 12 do not behave as an electric LC resonator having a resonance frequency corresponding to the wavelength λ of the electromagnetic wave.
Thanks to the form of the conductor elements 12, substantially as a linear or arched wire, the device for receiving and/or emitting an electromagnetic wave is compact in size along transversal or lateral directions X, Y perpendicular to the direction D.
The conductor elements 12 are close to each other in the lateral direction X, Y, two neighbour conductor elements being spaced apart from each other of a distance lower than λ/2. The electromagnetic field and the resonance of each conductor element 12 are coupled to the electromagnetic field and the resonance of the neighbour conductor element, therefore providing complex TEM modes.
Number | Date | Country | Kind |
---|---|---|---|
PCT/IB2009/056039 | Nov 2009 | WO | international |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP2010/067104 | 11/9/2010 | WO | 00 | 7/24/2012 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2011/054963 | 5/12/2011 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
7236138 | Wang | Jun 2007 | B2 |
7522105 | LaComb | Apr 2009 | B1 |
8102328 | Fink et al. | Jan 2012 | B2 |
20010038325 | Smith et al. | Nov 2001 | A1 |
20030227415 | Joannopoulos et al. | Dec 2003 | A1 |
20080088524 | Wang et al. | Apr 2008 | A1 |
20090040132 | Sridhar et al. | Feb 2009 | A1 |
Number | Date | Country |
---|---|---|
WO 0171774 | Sep 2001 | WO |
WO 2008007024 | Jan 2008 | WO |
WO 2010065555 | Jun 2010 | WO |
Entry |
---|
International Search Report dated May 18, 2010 for Application No. PCT/IB2009/056039. |
International Search Report dated Jan. 18, 2011 for Application No. PCT/EP2010/067143. |
Erentok, A., et al. “Characterization of a Volumetric Metamaterial Realization of an Artificial Magnetic Conductor for Antenna Applications”, IEEE Transactions on Antennas and Propagation, IEEE Service Center, Piscataway, NJ, US, Jan. 2005, vol. 53, No. 1, pp. 160-172. |
Fink, M., et al., “Time-reversed waves and super-resolution”, Comptes Rendus, Physique, Elsevier, Paris, FR, vol. 10, No. 5, pp. 447-463. |
Lemoult, F., et al., “Resonant Metalenses for Breaking the Diffraction Barrier”, The American Physical Society, May 21, 2010, No. 104, pp. 203901-1-203901-4. |
Mosallaei, H., et al. “Design and Modeling of Patch Antenna Printed on Magneto-Dielectric Embedded-Circuit Metasubstrate”, IEEE Transactions on Antennas and Propagation, Jan. 2007, vol. 55, No. 1, pp. 45-52. |
Shvets, G., et al., “Guiding, Focusing, and Sensing on the Subwavelength Scale Using Metallic Wire Arrays”, The American Physical Society, Aug. 3, 2007, No. 99, pp. 053903-1-053903-4. |
Number | Date | Country | |
---|---|---|---|
20120280886 A1 | Nov 2012 | US |