Metamaterial-Based Object-Detection System

Patent metadata

Field	Value
Publication number	US-2016011307-A1
Application number	US-201414331024-A
Country	US
Kind code	A1
Filing date	Jul 14, 2014
Priority date	Jul 14, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

An object-detection system for, e.g., a vehicle collision avoidance system, utilizes a metamaterial-based phase shifting element array to generate a scan beam by varying the effective capacitance of each metamaterial structure forming the array in order to control the phases of their radio frequency output signals such that the combined electromagnetic wave generated by the output signals is reinforced in the desired direction and suppressed in undesired directions to produce the scan beam. The metamaterial structures are configured to resonate at the same radio wave frequency as an incident input signal (radiation), whereby each metamaterial structure emits an associated output signal by way of controlled scattering the input signal. A variable capacitance is applied on each metamaterial structure, e.g., using varicaps that are adjusted by way of phase control voltages, to produce the desired output phase patterns. The metamaterial structures are constructed using inexpensive metal film or PCB fabrication technology.

First claim

1 . An object-detection system comprising:
a signal source configured to generate an input signal having a radio wave frequency; a phase shifting element array including a plurality of metamaterial structures, each said metamaterial structure configured to resonate at said radio wave frequency in response to said input signal such that said plurality of metamaterial structures respectively generate electromagnetic radiation output signals having said radio wave frequency by way of retransmitting said input signal; and a beam control circuit configured to generate a plurality of variable capacitances and to apply each said variable capacitance to an associated said metamaterial structure such that an effective capacitance of said associated metamaterial structure is altered by a corresponding change in each said applied variable capacitance, whereby said plurality of metamaterial structures respectively generate said electromagnetic radiation output signals at corresponding output phases determined by said plurality of variable capacitances, wherein said beam control circuit is further configured to vary said plurality of variable capacitances such that said output signals collectively generate a scan beam that sweeps across a field disposed in front of said phase shifting element array.

2 . The object-detection system according to claim 1 , wherein the beam control circuit comprises:
a plurality of variable capacitors configured to respectively generate associated variable capacitances, each said variable capacitor being coupled to an associated metamaterial structure of said plurality of metamaterial structures such that an effective capacitance of said associated metamaterial structure is altered by a corresponding change in the variable capacitance generated by said each variable capacitor; and a phase control circuit configured to generate a plurality of phase control voltages, each phase control voltage being applied to an associated variable capacitor of said plurality of variable capacitors such that said associated variable capacitance of said associated variable capacitor varies in accordance with said each phase control voltage, and each phase control voltage having a respective voltage level that varies over time such that said plurality of metamaterial structures respectively generate said output signals at a plurality of different output phases respectively coordinated to cause said scan beam to sweep across the field.

3 . The object-detection system of claim 2 , wherein each said variable capacitor is configured such that:
when said phase control voltage applied across said each variable capacitor has a first voltage level, said each variable capacitor generates said variable capacitance at a first capacitance level and said associated metamaterial structure generates said output signal at an associated first output phase, and when said phase control voltage is increased from said first voltage level to a second voltage level, said each variable capacitor generates said variable capacitance at a second capacitance level such that said associated metamaterial structure generates said output signal at an associated second output phase, said second output phase being greater than said first output phase.

4 . The object-detection system of claim 2 ,
wherein each said variable capacitor includes a first terminal and a second terminal, said first terminal connected to said associated metamaterial structure, and wherein said second terminal of all of said plurality of variable capacitors is connected to a common voltage source.

5 . The object-detection system of claim 2 , further comprising a plurality of conductive structures for respectively transmitting said plurality of phase control voltages, each said conductive structure connected between said phase control circuit and one of an associated metamaterial structure and said first terminal of said associated variable capacitor, whereby when one of said phase control voltages is applied by way of said each conductive structure and said second terminal of said associated variable capacitor is connected to a ground potential, said associated variable capacitor generates said associated variable capacitance having a capacitance level that is proportional to said phase control voltage.

6 . The object-detection system according to claim 2 ,
wherein said beam control circuit is further configured to generate beam direction data indicating an instantaneous beam direction of said scan beam, wherein said object-detection system further comprises: a receiver configured to detect beam portions of said scan beam that are reflected from objects disposed in said field, and configured to generate beam detection data indicating each detection of an associated reflected said beam portion, and signal processing circuitry configured to detect the position of an object in said field by combining said beam direction data with said beam detection data generated by reflection of said scan beam from said object.

7 . The object-detection system of claim 2 , wherein said phase shifting element array further comprises:
an electrically isolated lower metal layer; and a dielectric layer disposed over the lower metal layer, wherein each said metamaterial structure includes a metal island structure disposed on the dielectric layer and an associated lower layer portion of said lower metal layer, said associated lower layer portion being disposed directly under said metal island structure, and wherein said metal island structure and said associated lower layer portion of each said metamaterial structure are cooperatively configured such that said each metamaterial structure resonates at said radio wave frequency and has said fixed capacitance.

8 . The object-detection system of claim 7 , wherein said dielectric layer comprises a dielectric material.

9 . The object-detection system of claim 7 ,
wherein said phase shifting element array further comprises a base metal structure disposed on said upper dielectric surface and spaced from each said metal island structure of said plurality of metamaterial structures, and wherein each said variable capacitor of said plurality of variable capacitors includes a first terminal connected to said metal island structure of said associated metamaterial structure and a second terminal connected to said base metal structure.

10 . The object-detection system of claim 9 ,
wherein said base metal structure defines a plurality of openings, each said opening having an inner peripheral edge, wherein each said metal island structure is disposed inside an associated opening of said plurality of openings such that an outer peripheral edge of said metal island structure is separated from the inner peripheral edge of said base metal structure by a peripheral gap configured such that said metal island structures of each of the plurality of metamaterial structures resonates at said radio wave frequency.

11 . The object-detection system of claim 10 , wherein said base metal structure and said metal island structures comprise a single metal.

12 . The phased array apparatus of claim 7 , wherein said phase shifting element array further comprises a plurality of metal via structures, each said metal via structure extending through the dielectric layer and contacting the first terminal of an associated variable capacitor of said plurality of variable capacitors.

13 . The object-detection system of claim 7 , wherein said metal island structure of each of said plurality of metamaterial structures comprises a square peripheral edge.

14 . The phased array apparatus of c

Assignees

• Palo Alto Res Ct Inc

Inventors

• Casse Bernard D
• Volkel Armin R
• Liu Victor
• Tuganov Alexander S

Classifications

• G01S13/426

  Scanning radar, e.g. 3D radar (G01S13/66 takes precedence) · CPC title

• G01S13/931 Primary

  of land vehicles · CPC title

• H01Q3/46

  Active lenses or reflecting arrays · CPC title

• G01S2013/93271

  in the front of the vehicles · CPC title

• H01Q21/0093

  Monolithic arrays · CPC title