Compact resonant cavity antenna

Abstract

A reconfigurable antenna, includes an emissive region, including at least one radiating source designed to emit electromagnetic waves; and an electromagnetic lens, including a set of phase-shifting cells, including switches configured to introduce a phase shift to the electromagnetic waves, and bias lines to bias the switches. The antenna further includes an electromagnetic coupling region, arranged between the emissive region and the electromagnetic lens in order to generate electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells, wherein the electromagnetic coupling region comprises a set of electrically conductive elements, arranged to form a contour of a resonant cavity guiding the electromagnetic waves towards the electromagnetic lens, the set of electrically conductive elements comprising first tracks electrically connected to the bias lines.

Claims

1. A reconfigurable antenna, comprising: an emissive region including at least one radiating source configured to emit electromagnetic waves; an electromagnetic lens, including a set of phase-shifting cells, including switches configured to introduce a phase shift to the electromagnetic waves, and bias lines, configured to bias the switches; and an electromagnetic coupling region, arranged between the emissive region and the electromagnetic lens in order to generate electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells, wherein the electromagnetic coupling region comprises a set of electrically conductive elements, arranged to form a contour of a lateral part of a resonant cavity guiding the electromagnetic waves towards the electromagnetic lens, the set of electrically conductive elements including first tracks electrically connected to the bias lines; and the lateral part of the resonant cavity, which extends from the emissive region to the electromagnetic lens, connects a first open end and an opposing second open end of the resonant cavity.

2. The reconfigurable antenna according to claim 1, wherein the resonant cavity further comprises: the first open end, opening onto the electromagnetic lens; and the opposing second open end, opening onto the emissive region.

3. The reconfigurable antenna according to claim 1, wherein the electromagnetic coupling region extends in a dielectric medium.

4. The reconfigurable antenna according to claim 1, wherein the electromagnetic coupling region further comprises a dielectric substrate including interconnect levels, the first tracks being formed on the interconnect levels; and the set of electrically conductive elements includes first vias, configured to electrically connect the first tracks between the interconnect levels.

5. The reconfigurable antenna according to claim 1, wherein the set of electrically conductive elements comprises second tracks electrically connected to the bias lines.

6. The reconfigurable antenna according to claim 4, wherein the set of electrically conductive elements comprises second tracks electrically connected to the bias lines, the second tracks being formed on the interconnect levels; and the set of electrically conductive elements includes second vias configured to electrically connect the second tracks between the interconnect levels.

7. The reconfigurable antenna according to claim 5, further comprising switching elements configured to switch between the first and second tracks, the non-switched first or second tracks being at a floating electrical potential.

8. The reconfigurable antenna according to claim 1, wherein the set of electrically conductive elements is arranged such that the contour of the resonant cavity has a cross section that increases from the emissive region towards the electromagnetic lens.

9. The reconfigurable antenna according to claim 1, wherein the set of electrically conductive elements is arranged such that the contour of the resonant cavity exhibits axial symmetry.

10. The reconfigurable antenna according to claim 1, wherein the emissive region is planar.

11. The reconfigurable antenna according to claim 1, wherein the electromagnetic lens is planar.

12. The reconfigurable antenna according to claim 1, wherein the emissive region, the electromagnetic coupling region, and the electromagnetic lens are monolithic.

13. The reconfigurable antenna according to claim 1, wherein the resonant cavity has a thickness between λ and 10λ, where λ is a wavelength of the electromagnetic waves.

14. A passive antenna, comprising: an emissive region, including at least one radiating source configured to emit electromagnetic waves; an electromagnetic lens, including a set of phase-shifting cells configured to introduce a phase shift to the electromagnetic waves, and a ground plane; and an electromagnetic coupling region, arranged between the emissive region and the electromagnetic lens in order to generate electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells, wherein the electromagnetic coupling region comprises a set of electrically conductive elements, arranged to form a contour of a lateral part of a resonant cavity guiding the electromagnetic waves towards the electromagnetic lens, the set of electrically conductive elements including tracks electrically connected to the ground plane; and the lateral part of the resonant cavity, which extends from the emissive region to the electromagnetic lens, connects a first open end and an opposing second open end of the resonant cavity.

15. A reconfigurable antenna, comprising: an emissive region including at least one radiating source configured to emit electromagnetic waves; an electromagnetic lens, including a set of phase-shifting cells, including switches configured to introduce a phase shift to the electromagnetic waves, and bias lines, configured to bias the switches; and an electromagnetic coupling region, arranged between the emissive region and the electromagnetic lens in order to generate electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells, wherein the electromagnetic coupling region comprises a set of electrically conductive elements, arranged to form a contour of a resonant cavity guiding the electromagnetic waves towards the electromagnetic lens, the set of electrically conductive elements including first tracks electrically connected to the bias lines; the set of electrically conductive elements comprises second tracks electrically connected to the bias lines; and the antenna further comprises switching elements configured to switch between the first and second tracks, the non-switched first or second tracks being at a floating electrical potential.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages will become apparent in the detailed description of various embodiments of the invention, the description being accompanied by examples and references to the appended drawings.

(2) FIG. 1 is a schematic perspective view of an antenna according to the invention.

(3) FIG. 2 is a schematic exploded perspective view of an antenna according to the invention, illustrating a first embodiment of the resonant cavity. The dielectric medium is not shown in order to facilitate viewing.

(4) FIG. 3 is a schematic perspective view of an antenna according to the invention, illustrating a second embodiment of the resonant cavity. The dielectric medium is not shown in order to facilitate viewing.

(5) FIG. 4 is a schematic sectional view of a passive antenna according to the invention. The arrow indicates the direction of the radiation transmitted by the electromagnetic lens.

(6) FIG. 5 is a schematic sectional view of a reconfigurable antenna according to the invention, illustrating a first shape of the resonant cavity. The arrow indicates the direction of the radiation transmitted by the electromagnetic lens.

(7) FIG. 6 is a schematic sectional view of a reconfigurable antenna according to the invention, illustrating a second shape of the resonant cavity. The arrow indicates the direction of the radiation transmitted by the electromagnetic lens.

(8) FIG. 7 is a schematic sectional view of a reconfigurable antenna according to the invention, illustrating an embodiment where it is possible to switch between a first resonant cavity and a second resonant cavity of a different shape. The arrow indicates the direction of the radiation transmitted by the electromagnetic lens.

(9) The figures are not shown to scale for the sake of legibility and to simplify understanding thereof.

DETAILED DISCLOSURE OF THE EMBODIMENTS

(10) For the sake of simplicity, elements that are identical or that perform the same function in the various embodiments will bear the same references.

(11) One subject of the invention is a reconfigurable antenna 1, comprising: an emissive region ZE, comprising at least one radiating source S designed to emit electromagnetic waves; an electromagnetic lens 2, comprising: a set of phase-shifting cells 20, comprising switches 200 configured so as to introduce a phase shift to the electromagnetic waves, bias lines BL, designed to bias the switches 200; an electromagnetic coupling region ZC, arranged between the emissive region ZE and the electromagnetic lens 2 in order to generate electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells 20; the electromagnetic coupling region ZC comprises a set of electrically conductive elements, arranged so as to form a contour of a resonant cavity 3 guiding the electromagnetic waves towards the electromagnetic lens 2, the set of electrically conductive elements comprising first tracks P1 electrically connected to the bias lines BL.
Emissive Region

(12) The emissive region ZE is advantageously planar, such that each radiating source S is located equidistant from the electromagnetic lens 2.

(13) The or each radiating source S is advantageously configured so as to operate at a frequency between 1 GHz and 1 THz, preferably between 10 GHz and 300 GHz.

(14) The emissive region ZE is advantageously electrically connected to a transceiver, located at the rear of the antenna 1 or under the antenna 1.

(15) Electromagnetic Lens

(16) The electromagnetic lens 2 is advantageously planar.

(17) Each phase-shifting cell 20 may comprise: a first planar antenna (called receive antenna, not illustrated), designed to receive the incident wave emitted by the radiating source or sources S; a second planar antenna Tx (called transmit antenna), designed to transmit, with a phase shift, the incident wave received by the first planar antenna.

(18) The first planar antenna and the second planar antenna Tx are advantageously arranged on either side of a ground plane (not illustrated, except in FIG. 4 for a passive, non-reconfigurable antenna). The ground plane is preferably made of a metal material, more preferably copper. By way of non-limiting example, the ground plane may have a thickness of the order of 17 μm when the operating frequency of the transmitarray antenna is 29 GHz.

(19) The second planar antenna Tx advantageously has first and second radiating surfaces, separate in the sense that they are separated from one another by a separating region so as to be electrically isolated from one another. To this end, a slot is advantageously formed in the second planar antenna Tx in order to electrically isolate the separate first and second radiating surfaces. The slot defines the separating region. The slot is preferably annular, with a rectangular cross section. Of course, other shapes may be contemplated for the slot, such as an elliptical or circular shape. According to one variant implementation, the first and second radiating surfaces of the second planar antenna may be electrically isolated by a dielectric material.

(20) Each phase-shifting cell 20 advantageously comprises a phase shift circuit comprising first and second switches 200 respectively alternately having an on state and an off state, the on or off states corresponding to a respectively authorized or blocked flow of a current between the separate first and second radiating surfaces of the second planar antenna Tx. “Alternately” is understood to mean that the first switch 200 alternates between the on state and the off state, while, simultaneously, the second switch 200 alternates between the off state and the on state. In other words, at all times, the first and second switches 200 belonging to the same phase shift circuit have two opposing states, either on/off or off/on. On/on or off/off states are not authorized.

(21) By way of non-limiting examples, the switches 200 of the phase-shifting cells 20 may be PIN diodes, MEMS (“Micro Electro-Mechanical Systems”), NEMS (“Nano Electro-Mechanical Systems”). PIN diodes may be made from AlGaAs. Other implementation forms may be contemplated for the switches 200. By way of non-limiting examples, radiofrequency switches such as diodes, transistors, photodiodes and phototransistors are possible. The choice of a device for controlling the switches 200 depends on the technology that is chosen. By way of examples, the following devices may be used: an optical fibre for a photoelectric switch, a laser beam generated by external means and exciting a photoelectric switch, an electromagnetic wave according to the principles of remote power supply known from the field of RFID (“Radio Frequency Identification”).

(22) The bias lines BL are electrically conductive tracks, forming control means for controlling the switches 200 of the phase-shifting cells 20. The bias lines BL are preferably made from a metal material, more preferably copper. The bias lines BL may be electrically connected to the set of electrically conductive elements, and to the second planar antenna Tx, by way of transmission lines LT.

(23) Other phase-shifting cell 20 architectures may also be used, such as multilayer structures based on the concept of frequency-selective surfaces, or on the concept of Fabry-Perot cavities.

(24) Electromagnetic Coupling Region

(25) The electromagnetic coupling region ZC advantageously extends in a dielectric medium.

(26) The electromagnetic coupling region ZC advantageously comprises a dielectric substrate 4, comprising interconnect levels. By way of non-limiting example, the dielectric substrate 4 may be made of a commercial material such as RT/Duroid® 6002. The dielectric substrate 4 has a thickness typically of between 100 μm and 1500 μm for an operating frequency of the antenna of between 10 GHz and 300 GHz. By way of non-limiting example, the dielectric substrate 4 may have a thickness of the order of 4 mm when the operating frequency is 60 GHz.

(27) The first tracks P1 are advantageously formed on the interconnect levels. The set of electrically conductive elements advantageously comprises first vias V1, designed to electrically connect the first tracks P1 between the interconnect levels.

(28) The set of electrically conductive elements may comprise second tracks P2 electrically connected to the bias lines BL. The second tracks P2 are advantageously formed on the interconnect levels. The set of electrically conductive elements advantageously comprises second vias V2, designed to electrically connect the second tracks P2 between the interconnect levels. The antenna 1 advantageously comprises switching means 5 configured so as to switch between the first and second tracks P1, P2, the non-switched first or second tracks P1, P2 being at floating electrical potential. To this end, additional switching means 5′ may be provided on the bias lines BL such that the non-switched first or second tracks P1, P2 are at floating electrical potential.

(29) The resonant cavity 3 advantageously has: a first open end 30, opening onto the electromagnetic lens 2; an opposing second open end 31, opening onto the emissive region ZE; a lateral part 32, connecting the first and second open ends 30, 31, the contour of which is formed by the set of electrically conductive elements.

(30) The resonant cavity 3 is therefore defined by the emissive region ZE, the electromagnetic lens 2 and the set of electrically conductive elements. According to one embodiment, the resonant cavity 3 is defined by the emissive region ZE, the electromagnetic lens 2, the first tracks P1 and the first vias V1. In other words, the first tracks P1 and the first vias V1 form the contour of the lateral part 32 of the resonant cavity 3. According to another embodiment, the resonant cavity 3 is defined by the emissive region ZE, the electromagnetic lens 2, the second tracks P2 and the second vias V2. In other words, the second tracks P2 and the second vias V2 form the contour of the lateral part 32 of the resonant cavity 3.

(31) The resonant cavity 3 advantageously has a thickness between λ and 10λ, where λ is the wavelength of the electromagnetic waves. The size and shape of the resonant cavity 3 are defined by the template of the first and second tracks P1, P2 and of the first and second vias V1, V2. The template is determined by electromagnetic simulations according to the desired properties of the antenna 1.

(32) According to one embodiment, the set of electrically conductive elements is arranged such that the contour of the resonant cavity 3 has a cross section that increases from the emissive region ZE towards the electromagnetic lens 2.

(33) According to one embodiment, the set of electrically conductive elements is arranged such that the contour of the resonant cavity 3 exhibits axial symmetry.

(34) Monolithic Integration

(35) The emissive region ZE, the electromagnetic coupling region ZC and the electromagnetic lens 2 are advantageously monolithic, within the dielectric substrate 4.

(36) The antenna 1 may be manufactured with a planar technology allowing a monolithic implementation, preferably selected from among: PCB (“Printed Circuit Board”) technology, LTCC (“Low Temperature Co-fired Ceramic”) technology, WLP (“Wafer-Level Packaging”) technology.
Passive Antenna (Fixed Beam)

(37) Another subject of the invention is a passive antenna 1, comprising: an emissive region ZE, comprising at least one radiating source S designed to emit electromagnetic waves; an electromagnetic lens 2, comprising: a set of phase-shifting cells 20, configured so as to introduce a phase shift to the electromagnetic waves, a ground plane PM; an electromagnetic coupling region ZC, arranged between the emissive region ZE and the electromagnetic lens 2 in order to generate electromagnetic coupling between the electromagnetic waves and the set of phase-shifting cells 20; the electromagnetic coupling region ZC comprises a set of electrically conductive elements, arranged so as to form a contour of a resonant cavity 3 guiding the electromagnetic waves towards the electromagnetic lens 2, the set of electrically conductive elements comprising tracks P electrically connected to the ground plane PM.

(38) The ground plane PM is preferably made of a metal material, more preferably copper. By way of non-limiting example, the ground plane PM may have a thickness of the order of 17 μm when the operating frequency of the transmitarray antenna is 29 GHz.

(39) Each phase-shifting cell 20 may comprise: a first planar antenna (called receive antenna, not illustrated), designed to receive the incident wave emitted by the radiating source or sources S; a second planar antenna Tx (called transmit antenna), designed to transmit, with a phase shift, the incident wave received by the first planar antenna.

(40) Other phase-shifting cell 20 architectures may also be used, such as multilayer structures based on the concept of frequency-selective surfaces, or on the concept of Fabry-Perot cavities.

(41) The first planar antenna and the second planar antenna Tx are arranged on either side of the ground plane PM. The ground plane PM may be electrically connected to the set of electrically conductive elements by way of transmission lines LT.

(42) The electromagnetic coupling region ZC advantageously comprises a dielectric substrate 4, comprising interconnect levels. The tracks P are advantageously formed on the interconnect levels. The set of electrically conductive elements advantageously comprises vias V, designed to electrically connect the tracks P between the interconnect levels.

(43) The resonant cavity 3 advantageously has: a first open end 30, opening onto the electromagnetic lens 2; an opposing second open end 31, opening onto the emissive region ZE; a lateral part 32, connecting the first and second open ends 30, 31, the contour of which is formed by the set of electrically conductive elements.

(44) The resonant cavity 3 advantageously has a thickness between λ and 10λ, where λ is the wavelength of the electromagnetic waves.

(45) The invention is not limited to the described embodiments. A person skilled in the art has the ability to consider technically operative combinations thereof and to substitute them for equivalents.