US6512494B1 — Multi-resonant, high-impedance electromagnetic su…

Claim 1

Independent Claim 98 words

An artificial magnetic conductor (AMC), the AMC characterized by an effective media model comprising: a first layer and a second layer, each layer having a layer tensor permittivity and a layer tensor permeability, each said layer tensor permittivity and each said layer tensor permeability having non-zero elements on a main diagonal only, x and y tensor directions being in-plane with each respective layer and z tensor direction being normal to each layer the first layer including a specific arrangement of conducting and dielectric regions chosen to produce, resonance at predetermined multiple frequencies which are not necessarily harmonically related.

Claim 2

Dependent Claim 98 words

An artificial magnetic conductor (AMC), the AMC characterized by an effective media model comprising: a first layer and a second layer, each layer having a layer tensor permittivity and a layer tensor permeability, each said layer tensor permittivity and each said layer tensor permeability having non-zero elements on a main diagonal only, x and y tensor directions being in-plane with each respective layer and z tensor direction being normal to each layer the first layer including a specific arrangement of conducting and dielectric regions chosen to produce, resonance at predetermined multiple frequencies which are not necessarily harmonically related.

Claim 3

Dependent Claim 26 words

The AMC of claim 1 wherein the first layer and the second layer are electrically thin relative to the free space wavelength of the resonance frequencies.

Claim 4

Dependent Claim 38 words

The AMC of claim 2 wherein the first layer has a thickness t and the second layer has a thickness h and wherein h<λ/10 and t<λ/10, wherein λ corresponds to the free space wavelength of the resonance frequencies.

Claim 5

Dependent Claim 31 words

The AMC of claim 1 wherein the second layer is characterized by a periodic rodded media including rods having longitudinal axes parallel to the z tensor direction within a host medium.

Claim 6

Dependent Claim 26 words

The AMC of claim 4 wherein the permittivities of the second layer in the x tensor direction and the y tensor direction are independent of frequency.

Claim 7

Dependent Claim 31 words

The AMC of claim 5 wherein the permittivities of the second layer in the x tensor direction and the y tensor direction are within 5% of the host medium dielectric value.

Claim 8

Dependent Claim 24 words

The AMC of claim 4 wherein the permittivity of the second layer in the z tensor direction is negative at the multiple resonance frequencies.

Claim 9

Dependent Claim 21 words

The AMC of claim 4 further comprising a conductive ground plane electrically coupled with one end of each of the rods.

Claim 10

Dependent Claim 40 words

The AMC of claim 8 wherein the second layer comprises: a periodic array of rods disposed within the host medium, each rod having a predetermined cross section having dimensions small relative to the free space wavelength of the resonance frequencies.

Claim 11

Dependent Claim 37 words

The AMC of claim 1 wherein the first layer is characterized by transverse permittivities in the y tensor direction and the x tensor direction which are variable with frequency and which exhibit one or more Lorentz resonances.

Claim 12

Dependent Claim 26 words

The AMC of claim 10 wherein the transverse permittivity in the y tensor direction is substantially equal to the transverse permittivity in the x tensor direction.

Claim 13

Dependent Claim 32 words

The AMC of claim 10 wherein the transverse permittivity in the y tensor direction does not equal the transverse permittivity in the x tensor direction to produce an anisotropic high impedance surface.

Claim 14

Dependent Claim 21 words

The AMC of claim 10 wherein the one or more Lorentz resonances fall between the multiple resonant frequencies of the AMC.

Claim 15

Dependent Claim 161 words

The AMC of claim 10 wherein the transverse permittivity of the first layer is modeled by ɛ 1  t = Y  ( ω ) jωɛ 0  t where Y(ω) is an admittance function described by Foster's second canonical form for a one port circuit, Y  ( ω ) = jω   C ∞ + 1 jω   L o + ∑ n = 1 N  1 R n + jω   L n + 1 jω   C n , where j is the imaginary operator, ω is radian frequency, ε o is the permittivity of free space, C ∞ is the asymptotic limit on transverse capacitance of the first layer as ω approaches an infinite value, L o is the asymptotic limit on shunt inductance of the model as ω approaches 0, R n is a branch resistance, L n is a branch inductance and C n is a branch capacitance.

Claim 16

Dependent Claim 24 words

The AMC of claim 14 wherein the poles of Y(ω) correspond to Lorentz resonances in transverse permittivities in the x and y tensor directions.

Claim 17

Dependent Claim 27 words

The AMC of claim 14 where in the number of the multiple resonance frequencies of the AMC is one more than the number of poles of Y(ω).

Claim 18

Dependent Claim 31 words

The AMC of claim 10 wherein the first layer is characterized by a normal permittivity in the z tensor direction which is substantially constant with frequency and substantially equal to 1.

Claim 19

Dependent Claim 147 words

The AMC of claim 10 wherein the normal permeability of the first layer is modeled by μ 1  z = Z  ( ω ) jωμ 0  t where Z(ω) is an impedance function described by Foster's first canonical form for a one port circuit, Z  ( ω ) = jω   L ∞ + 1 jω   C o + ∑ n = 1 N  1 G n + jω   C n + 1 jω   L n , where ω is radian frequency, L ∞ is the asymptotic limit on series inductance of the model as ω approaches an infinite value, C o is the asymptotic limit on the circuit capacitance as ω approaches 0, G n is a conductance, C n is a capacitance, and L n is an inductance for an nth antiresonant circuit.

Claim 20

Dependent Claim 24 words

The AMC of claim 18 wherein poles of Z(ω) are Lorentz resonances in normal permeability of the first layer in the z tensor direction.

Claim 21

Dependent Claim 78 words

The AMC of claim 1 wherein the multiple resonance frequencies of the AMC satisfy the equation ɛ 1  t = 1 ω 2  μ 2  t  μ 0  ɛ 0  ht , where ε 1t is the transverse permittivity of the first layer, μ 2t is the transverse permeability of the second layer, ω=2πf is radian frequency, and t and h are thicknesses of the first layer and the second layer, respectively.

Claim 22

Dependent Claim 32 words

The AMC of claim 20 wherein the multiple resonance frequencies of the AMC further satisfy the relation ɛ 1  t = Y  ( ω ) jωɛ 0  t .

Claim 23

Dependent Claim 62 words

The AMC of claim 21 wherein intersections of the equations ɛ 1  t = 1 ω 2  μ 2  t  μ 0  ɛ 0  ht   and   ɛ 1  t = Y  ( ω ) jωɛ 0  t define the multiple resonant frequencies where AMC reflection phase goes to zero.

Claim 24

Dependent Claim 118 words

An artificial magnetic conductor operable over at least a first high-impedance frequency band and a second high-impedance frequency band as a high-impedance surface, the artificial magnetic conductor being defined by an effective media model comprising: a spacer layer; and a frequency selective surface (FSS) disposed adjacent the spacer layer and having a transverse permittivity so, defined by ɛ 1  x = ɛ 1  y = Y  ( ω ) jωɛ 0  t , wherein Y(ω) is a frequency dependent admittance function for the frequency selective surface, j is the imaginary operator, ω corresponds to angular frequency, ε 0 is the permittivity of free space, and t corresponds to thickness of the frequency selective surface.

Claim 25

Dependent Claim 118 words

An artificial magnetic conductor operable over at least a first high-impedance frequency band and a second high-impedance frequency band as a high-impedance surface, the artificial magnetic conductor being defined by an effective media model comprising: a spacer layer; and a frequency selective surface (FSS) disposed adjacent the spacer layer and having a transverse permittivity so, defined by ɛ 1  x = ɛ 1  y = Y  ( ω ) jωɛ 0  t , wherein Y(ω) is a frequency dependent admittance function for the frequency selective surface, j is the imaginary operator, ω corresponds to angular frequency, ε 0 is the permittivity of free space, and t corresponds to thickness of the frequency selective surface.

Claim 26

Dependent Claim 68 words

The artificial magnetic conductor of claim 23 wherein the FSS layer has a normal permeability μ 1z μ 1  z = Z  ( ω ) jωμ 0  t , wherein Z(ω) is a frequency dependent impedance function, j is the imaginary operator, ω corresponds to angular frequency, μ 0 is the permeability of free space, and t corresponds to thickness of the frequency selective surface.

Claim 27

Dependent Claim 57 words

The artificial magnetic conductor of claim 24 wherein the spacer layer and the frequency selective surface each are defined by a permittivity tensor ɛ i = ɛ 0  ( ɛ it 0 0 0 ɛ it 0 0 0 ɛ in ) , where i=1 for the frequency selective surface and i=2 for the spacer layer.

Claim 28

Dependent Claim 57 words

The artificial magnetic conductor of claim 23 wherein the spacer layer and the frequency selective surface each are defined by a permeability tensor μ i = μ 0  ( μ it 0 0 0 μ it 0 0 0 μ in ) , where i=1 for the frequency selective surface and i=2 for the spacer layer.

Claim 29

Dependent Claim 38 words

The artificial magnetic conductor of claim 23 wherein the transverse permittivity has one or more Lorentz resonances at predetermined frequencies located between the first high-impedance frequency band and the second high-impedance frequency band of the artificial magnetic conductor.

Claim 30

Dependent Claim 60 words

The artificial magnetic conductor of claim 23 further comprising: an array of artificial magnetic molecules including a first planar array of conductive loops; and a second planar array of conductive loops spaced a distance t from the first planar array of conductive loops, each loop of the second planar array overlapping one or more loops of the first planar array.

Claim 31

Dependent Claim 98 words

An artificial magnetic conductor (AMC) resonant with a substantially zero degree reflection phase over two or more AMC resonant frequency bands, the artificial magnetic conductor comprising: a spacer layer including an array of metal posts extending through the spacer layer; and a frequency selective surface (FSS) disposed on the spacer layer in which the frequency selective surface comprises specific geometric arrangements of metal and dielectric regions, wherein such regions have been designed to exhibit one or more Lorentz resonances in the presence of electromagnetic waves at predetermined frequencies different from the two or more AMC resonant frequency bands.

Claim 32

Dependent Claim 98 words

An artificial magnetic conductor (AMC) resonant with a substantially zero degree reflection phase over two or more AMC resonant frequency bands, the artificial magnetic conductor comprising: a spacer layer including an array of metal posts extending through the spacer layer; and a frequency selective surface (FSS) disposed on the spacer layer in which the frequency selective surface comprises specific geometric arrangements of metal and dielectric regions, wherein such regions have been designed to exhibit one or more Lorentz resonances in the presence of electromagnetic waves at predetermined frequencies different from the two or more AMC resonant frequency bands.

Claim 33

Dependent Claim 26 words

The artificial magnetic conductor of claim 29 wherein the frequency selective surface has an in-plane permittivity having one or more Lorentz resonances at the predetermined frequencies.

Claim 34

Dependent Claim 18 words

The artificial magnetic conductor of claim 30 wherein the frequency selective surface has a frequency variable normal permeability.

Claim 35

Dependent Claim 26 words

The artificial magnetic conductor of claim 31 wherein the frequency selective surface has a normal permeability having one or more Lorentz resonances at the predetermined frequencies.

Claim 36

Dependent Claim 22 words

The artificial magnetic conductor of claim 29 wherein the AMC resonant frequency bands of zero degree reflection phase are not harmonically related.

Claim 37

Dependent Claim 25 words

The artificial magnetic conductor of claim 29 further comprising: a conductive ground plane adjacent the spacer layer and electrically contacting the array of metal posts.

Claim 38

Dependent Claim 18 words

The artificial magnetic conductor of claim 29 wherein the frequency selective surface has a frequency dependent in-plane permittivity.

Claim 39

Dependent Claim 23 words

The artificial magnetic conductor of claim 35 wherein frequency dependence of the in-plane permittivity is independent of frequency dependence of the normal permeability.

Claim 40

Dependent Claim 36 words

The artificial magnetic conductor of claim 36 wherein the predetermined reflection phase resonant frequencies are not harmonically related, and wherein the lowest two reflection phase resonant frequencies are spaced to have a ratio less than 3:1.

Claim 41

Dependent Claim 22 words

The artificial magnetic conductor of claim 29 wherein the frequency selective surface exhibits capacitive coupling between elements of the frequency selective surface.

Claim 42

Dependent Claim 18 words

The artificial magnetic conductor of claim 29 wherein the frequency selective surface comprises a plurality of conductive layers.

Claim 43

Dependent Claim 37 words

The artificial magnetic conductor of claim 39 wherein the plurality of layers exhibit a strong capacitive coupling between each layer such that a low frequency limit of relative transverse permittivity for the FSS is at least 10.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2006-01-27	2006-07-29	2007-01-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2010-01-27	2010-07-29	2011-01-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2014-01-27	2014-07-29	2015-01-28	$7700.00	Window Closed / Lapsed

Multi-resonant, high-impedance electromagnetic surfaces

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