US6552696B1 — Electronically tunable reflector

Claim 1

Independent Claim 74 words

A tuneable impedance surface for steering and/or focusing an incident radio frequency beam, the tunable surface comprising: (a) a ground plane; (b) a plurality of elements spaced from the ground plane by a distance or distances less than a wavelength of the radio frequency beam; and (b) a capacitor arrangement for controllably varying the capacitance of adjacent elements including a dielectric material which locally changes its dielectric constant in response to an external stimulus.

Claim 2

Dependent Claim 74 words

A tuneable impedance surface for steering and/or focusing an incident radio frequency beam, the tunable surface comprising: (a) a ground plane; (b) a plurality of elements spaced from the ground plane by a distance or distances less than a wavelength of the radio frequency beam; and (b) a capacitor arrangement for controllably varying the capacitance of adjacent elements including a dielectric material which locally changes its dielectric constant in response to an external stimulus.

Claim 3

Dependent Claim 37 words

The tuneable impedance surface of claim 1 further including an insulator for supporting said ground plane on one major surface thereof and for supporting a first group of said plurality of elements on another major surface thereof.

Claim 4

Dependent Claim 27 words

The tuneable impedance surface of claim 2 further including a second insulator for supporting a second group of said plurality of elements on a major surface thereof.

Claim 5

Dependent Claim 35 words

The tuneable impedance surface of claim 3 wherein said capacitor arrangement is adjustable to electrically tune the impedances of said plurality of elements, said external stimulus being provided by a plurality of AC bias signals.

Claim 6

Dependent Claim 28 words

The tuneable impedance surface of claim 4 wherein the plurality of elements each have an outside dimension which is less than the wavelength of the radio frequency beam.

Claim 7

Dependent Claim 19 words

The tuneable impedance surface of claim 5 wherein the first group of elements is coupled to the ground plane.

Claim 8

Dependent Claim 21 words

The tuneable impedance surface of claim 6 wherein the second group of elements is coupled to receive the AC bias signals.

Claim 9

Dependent Claim 44 words

The tuneable impedance surface of claim 7 wherein the second insulator is disposed in a spaced, parallel relationship to the first mentioned insulator, the dielectric material which locally changes its dielectric constant in response to an external stimulus being disposed between the two insulators.

Claim 10

Dependent Claim 28 words

The tuneable impedance surface of claim 8 wherein the dielectric material which locally changes its dielectric constant in response to an external stimulus is a liquid crystal material.

Claim 11

Dependent Claim 19 words

The tuneable impedance surface of claim 9 wherein the plurality of elements are arranged in a two dimensional array.

Claim 12

Dependent Claim 19 words

The tuneable impedance surface of claim 9 wherein the plurality of elements are arranged in a one dimensional array.

Claim 13

Dependent Claim 23 words

The tuneable impedance surface of claim 4 further including a plurality of MEMS capacitors coupled between adjacent ones of said plurality of elements.

Claim 14

Dependent Claim 24 words

The tuneable impedance surface of claim 12 wherein said plurality of MEMS capacitors are coupled between adjacent ones of said second group of elements.

Claim 15

Dependent Claim 23 words

The tuneable impedance surface of claim 1 further including a plurality of MEMS capacitors coupled between adjacent ones of said plurality of elements.

Claim 16

Dependent Claim 36 words

The tuneable impedance surface of claim 1 wherein said plurality of elements are grouped into first and second groups, the first group being coupled to said ground plane and the second group receiving said external stimulus.

Claim 17

Dependent Claim 15 words

The tuneable impedance surface of claim 15 wherein the external stimulus is a bias voltage.

Claim 18

Independent Claim 102 words

A method of tuning a high impedance surface for a radio frequency signal comprising: arranging a plurality of generally spaced-apart planar conductive surfaces in an array disposed essentially parallel to and spaced from a conductive back plane, the size of each conductive surface being less than a wavelength of the radio frequency signal and the spacing of each conductive surface from the back plane being less than a wavelength of the radio frequency signal; and varying the capacitance between adjacent conductive surfaces by locally varying a dielectric constant of a dielectric material to thereby tune the impedance of said high impedance surface.

Claim 19

Independent Claim 102 words

A method of tuning a high impedance surface for a radio frequency signal comprising: arranging a plurality of generally spaced-apart planar conductive surfaces in an array disposed essentially parallel to and spaced from a conductive back plane, the size of each conductive surface being less than a wavelength of the radio frequency signal and the spacing of each conductive surface from the back plane being less than a wavelength of the radio frequency signal; and varying the capacitance between adjacent conductive surfaces by locally varying a dielectric constant of a dielectric material to thereby tune the impedance of said high impedance surface.

Claim 20

Dependent Claim 19 words

The method of claim 17 wherein said plurality of generally spaced-apart planar conductive surfaces are arranged on an insulator.

Claim 21

Dependent Claim 30 words

The method of claim 17 wherein the step varying the capacitance between adjacent conductive surfaces in said array includes providing bias signals to capacitor electrodes disposed adjacent said dielectric material.

Claim 22

Dependent Claim 39 words

The method of claim 17 further including providing MEMS capacitors between adjacent ones of said spaced-apart planar conductive surfaces and wherein the step of varying the capacitance between adjacent conductive surfaces includes applying bias signals to said MEMS capacitors.

Claim 23

Dependent Claim 97 words

A tunable reflective surface for a radio frequency signal comprising: a conductive ground plane; a plurality of generally spaced-apart planar conductive surfaces in an array disposed essentially parallel to and spaced from the ground plane, the size of each conductive surface being less than a wavelength of the radio frequency signal and the spacing of each conductive surface from the ground plane being less than a wavelength of the radio frequency signal; and a material having a locally varying dielectric constant disposed adjacent said plurality of generally spaced-apart planar conductive surfaces and spaced from said ground plane.

Claim 24

Dependent Claim 97 words

A tunable reflective surface for a radio frequency signal comprising: a conductive ground plane; a plurality of generally spaced-apart planar conductive surfaces in an array disposed essentially parallel to and spaced from the ground plane, the size of each conductive surface being less than a wavelength of the radio frequency signal and the spacing of each conductive surface from the ground plane being less than a wavelength of the radio frequency signal; and a material having a locally varying dielectric constant disposed adjacent said plurality of generally spaced-apart planar conductive surfaces and spaced from said ground plane.

Claim 25

Dependent Claim 22 words

The tunable reflective surface of claim 21 wherein said plurality of generally spaced-apart planar conductive surfaces are arranged on an insulating substrate.

Claim 26

Dependent Claim 45 words

The tunable reflective surface of claim 22 further including a plurality of capacitor electrodes disposed adjacent said dielectric material and spaced from said plurality of generally spaced-apart planar conductive surfaces and means for providing bias signals to said capacitor electrodes disposed adjacent said dielectric material.

Claim 27

Dependent Claim 35 words

The tunable reflective surface of claim 23 wherein the plurality of generally spaced-apart planar conductive surfaces are disposed on the insulating substrate and wherein the plurality of capacitor electrodes are disposed on a second substrate.

Claim 28

Independent Claim 115 words

A method of tuning a high impedance surface for reflecting a radio frequency signal therefrom, the method including: arranging a plurality of generally spaced-apart planar conductive surfaces in an array disposed essentially parallel to and spaced from a conductive back plane, the size of each conductive surface being less than a wavelength of the radio frequency signal and the spacing of each conductive surface from the back plane being less than a wavelength of the radio frequency signal; and varying the capacitance between adjacent conductive surfaces while the radio frequency signal is being reflected from said high impedance surface by locally varying a dielectric constant of a dielectric material disposed adjacent to said conductive surfaces.

Claim 29

Independent Claim 115 words

A method of tuning a high impedance surface for reflecting a radio frequency signal therefrom, the method including: arranging a plurality of generally spaced-apart planar conductive surfaces in an array disposed essentially parallel to and spaced from a conductive back plane, the size of each conductive surface being less than a wavelength of the radio frequency signal and the spacing of each conductive surface from the back plane being less than a wavelength of the radio frequency signal; and varying the capacitance between adjacent conductive surfaces while the radio frequency signal is being reflected from said high impedance surface by locally varying a dielectric constant of a dielectric material disposed adjacent to said conductive surfaces.

Claim 30

Dependent Claim 20 words

The method of claim 25 wherein said plurality of generally spaced-apart planar conductive surfaces are arranged on said dielectric material.

Claim 31

Dependent Claim 30 words

The method of claim 25 wherein the step varying the capacitance between adjacent conductive surfaces in said array includes providing bias signals to capacitor electrodes disposed adjacent said dielectric material.

Claim 32

Dependent Claim 39 words

The method of claim 25 further including providing MEMS capacitors between adjacent ones of said spaced-apart planar conductive surfaces and wherein the step of varying the capacitance between adjacent conductive surfaces includes applying bias signals to said MEMS capacitors.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2006-04-21	2006-10-21	2007-04-22	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2010-04-21	2010-10-21	2011-04-22	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2014-04-21	2014-10-21	2015-04-22	$7700.00	Window Closed / Lapsed

Electronically tunable reflector

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