WO2015126521A1 - Conducteur magnétique artificiel actif - Google Patents

Conducteur magnétique artificiel actif Download PDF

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Publication number
WO2015126521A1
WO2015126521A1 PCT/US2014/072233 US2014072233W WO2015126521A1 WO 2015126521 A1 WO2015126521 A1 WO 2015126521A1 US 2014072233 W US2014072233 W US 2014072233W WO 2015126521 A1 WO2015126521 A1 WO 2015126521A1
Authority
WO
WIPO (PCT)
Prior art keywords
patch
aamc
top face
corner
crossed slot
Prior art date
Application number
PCT/US2014/072233
Other languages
English (en)
Inventor
Carson R. White
Daniel J. Gregoire
Original Assignee
Hrl Laboratories, Llc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US14/188,225 external-priority patent/US9379448B2/en
Priority claimed from US14/188,264 external-priority patent/US20150244079A1/en
Application filed by Hrl Laboratories, Llc filed Critical Hrl Laboratories, Llc
Priority to EP14882944.3A priority Critical patent/EP3111509A4/fr
Priority to CN201480072872.7A priority patent/CN105900282A/zh
Publication of WO2015126521A1 publication Critical patent/WO2015126521A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
    • H01Q15/0086—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices having materials with a synthesized negative refractive index, e.g. metamaterials or left-handed materials

Definitions

  • artificial magnetic conductors are metasurfaces that reflect incident electromagnetic waves in phase.
  • AMCs are typically composed of unit cells that are less than a half-wavelength and achieve their properties by resonance.
  • Active circuits for example negative inductors or non-Foster circuits (NFCs), have been employed to increase the bandwidth, thus constituting an active AMC (AAMC) .
  • NFCs non- Foster circuits
  • AAMCs may improve antennas in a number of ways including 1) increasing antenna bandwidth, as described in references [6] and [11] below, 2) reducing finite ground plane edge effects for antennas mounted on structures to improve their radiation pattern, 3) reducing coupling between antenna elements spaced less than one wavelength apart on structures to mitigate co-site interference, 4) enabling radiation of energy polarized parallel to and directed along structural metal surfaces, and 5) increase the bandwidth and efficiency of cavity-backed slot antennas while reducing cavity size.
  • Use of AAMC technology is particularly applicable for frequencies less than 1 GHz where the physical size of a traditional AMC becomes prohibitive for most practical applications.
  • AMCs may have limited bandwidth. Their bandwidth is proportional to the substrate thickness and permeability, as described in references [1] to [4] below.
  • An AMC is loaded with non-Foster circuit (NFC) negative inductors, as described in references [1] to [6] below, and an AAMC may have an increased bandwidth of 10 x or more compared to an AMC, as described in references [1] , [4] and [5] below.
  • NFC non-Foster circuit
  • FIG. 1 A prior-art AAMC unit cell architecture is shown in FIG. 1.
  • the AAMC has a ground plane 12, a 2.54 cm thick foam substrate 14, a 0.76 mm thick dielectric substrate 16, copper patches 18, which are about 65 mm wide and long, a 10 mm gap 20 between patches 18, a non-Foster circuits (NFC) 22 between patches 18, a wiring access hole 24, and a via to ground 26.
  • the patches 18 are about 50 ⁇ thick.
  • AMC Artificial Magnetic Conductor
  • AMC response can be accurately modeled over a limited frequency range using an equivalent parallel LRC circuit with L ⁇ mc , C mc , and Rmc as the circuits' inductance, capacitance and resistance respectively, as described in references [l]to[3] and [7] below.
  • the circuit impedance is J ⁇ AMC
  • An AMC of the form shown in FIG. 1, where a grounded dielectric substrate is covered with a grid of metallic patches loaded with lumped elements between the patches can be
  • d is the dielectric thickness
  • ⁇ and ⁇ are the substrate's permittivity and permeability respectively.
  • the loaded AMC reflection properties can be estimated by equating the LRC circuit parameters of equation (1) to quantities in the transmission line model of equations (3) and (4). If the load is capacitive, then the equivalent LRC circuit parameters are
  • the AAMC is loaded with non-Foster circuit (NFC) negative inductors, as described in references [1] and [6] below.
  • NFC non-Foster circuit
  • the NFC is the critical element that enables realization of the AAMC and its high bandwidth.
  • the NFC name alludes to the fact that it circumvents Foster' s reactance theorem, as
  • FIG. 2A shows an NFC circuit 30 on a carrier board, which also has capacitors 32, RF (radio frequency) pads 34, and DC (direct current) pads 36.
  • the NFC can be represented by the equivalent circuit model shown in FIG. 2B.
  • the desired negative inductance, R NFC is negative resistance.
  • C NFC and G NFC are positive capacitance and conductance, respectively.
  • R NFC , C NFC and G NFC are all equal to zero.
  • the equivalent circuit parameters vary according to the bias voltage applied and some prior-art NFC circuit parameters are plotted in FIG. 3.
  • NFCs become unstable when the bias voltage goes too high, when they are subjected to excessive RF power, or when they have detrimental coupling with neighboring NFCs.
  • the instability is manifested as circuit oscillation and emission of radiation from the circuit.
  • the NFCs in an AAMC become unstable, the AAMC no longer operates as an AMC .
  • the coax AAMC appears to the incident wave in the coax as an infinite array of unit cells because of its azimuthal
  • the fields are polarized radially, and neighboring NFCs do not couple unstably because their separation is perpendicular to the field polarization.
  • inductance is tuned from -70 to -49.5 nH.
  • the phase and magnitude of a reflected wave vs. frequency is shown.
  • the resonant frequency can be tuned from approximately 470 MHz to 220 MHz while maintaining stability.
  • the ⁇ 90° bandwidth is more than 80%, spanning the range from 160 to 391 MHz.
  • the prior-art AAMC has much higher bandwidth than an equivalent passive AMC, as shown in FIG. 6.
  • the AAMC has better than five times the bandwidth of a varactor-loaded AMC at high loading levels .
  • AAMC polarization independent active artificial magnetic conductor
  • an active artificial magnetic conductor comprises an array of unit cells, each unit cell comprising a top face, at least one wall coupled to the top face, a base coupled to the at least one wall, and a crossed slot in the top face, ⁇ wherein the top face, the at least one wall, and the base form a cavity, and wherein the top face, the at least one wall, and the base are
  • FIG. 2A shows a non-Foster circuit (NFC) on a carrier board in accordance with the prior art
  • FIG. 2B shows an equivalent circuit for a non-Foster circuit (NFC) in accordance with the prior art
  • FIG. 3 shows circuit parameters of a prior art non- Foster circuit in accordance with the prior art
  • FIGs. 4A and 4B show a single-polarization AAMC in accordance with the prior art
  • FIG. 5A shows a single-polarization coaxial AAMC
  • FIG. 5B shows a coaxial TEM cell used for measuring the coaxial AAMC of FIG. 5A
  • FIG. 5C shows the reflection properties of a coaxial AAMC in accordance with the prior art
  • FIG. 7A shows an active artificial magnetic conductor (AAMC) and FIG. 7B shows a unit cell of an AAMC in accordance with the present disclosure
  • FIG. 8A shows a single polarized version of a unit cell in accordance with the present disclosure
  • FIGs. 9A shows a whole unit cell and 9B shows a differential /common mode quarter circuit when an incident field is y-polarized in accordance with the present disclosure
  • FIGs. 10A, 10B and IOC show loading configurations for an NFC: FIG. 10A for a square configuration with 4 NFCs, FIG. 10B for a cross (X) configuration with 4 NFCs, and FIG. IOC for a crossover configuration with 2 NFCs in accordance with the present disclosure;
  • FIGs. 11A and 11B show a reflection phase of an AAMC unit cell for d equal to 75mm and 100mm, respectively, in accordance with the present disclosure.
  • FIGs. 12A, 12B and 12C show a summary of performance of a dual-polarized cavity backed slot (CBS) AAMC for d equal to 75mm and 100 mm in accordance with the present disclosure.
  • CBS dual-polarized cavity backed slot
  • a dual-polarized active artificial magnetic conductor which has a periodic array of unit cells that reflect electromagnetic waves polarized parallel to a surface with zero-degree phase.
  • Each unit cell has a cavity with conducting walls with a top surface which may be planar or curved surface, and a crossed slot patterned in the top surface forming an aperture.
  • AMC operation is achieved when the unit cell is near its parallel resonance.
  • the resonance frequency is reduced and the bandwidth increased by connecting negative- inductance circuits, which is a class of non-Foster circuits (NFCs) across the slot, preferably near the center of the unit cell.
  • the cavity and crossed slot may possess two orthogonal planes of symmetry that are further orthogonal to the top surface. The responses in the two principle planes may be tuned to the same frequency or different frequencies.
  • the unit cell 20 as shown in FIG. 7B, has a cavity 22 filled with air, dielectric, and/or magnetic material.
  • the unit cell 20 is preferably symmetric about the x-z and y-z axes, and has a top face 24 that is planar.
  • the cavity 22 is
  • the walls 26 of the cavity 22 are conductive and a crossed slot 31 is patterned in the top face 24 forming an aperture such that it is symmetric about the x-z and y-z planes, as shown in FIG. 7B.
  • the crossed slot 31 preferably extends to the cavity walls 26.
  • the top face 24 is divided by the crossed slot 31 into four patches 30, 32, 34 and 36. Each of the four patches 30, 32, 34 and 36 of the top face 24 is conductive.
  • the walls 26 of the cavity and the base 27 of the cavity are also conductive .
  • a rectangular slot 40 with a width w 42 much less than length d 43 is cut into the top face 46 along an x-axis 48.
  • AAMC behavior occurs when the surface impedance of an incident wave goes through a parallel resonance.
  • Cavity-backed slot antennas CBSAs are parallel resonant antennas in their first resonance, as described in reference [12].
  • An AAMC structure may be considered to be an infinite array of CBSAs where each element can be modeled by Floquet analysis, where an antenna port 50 has antenna terminals across the center of the slot 40 and another port is the y-polarized radiation mode at a specified angle, for example at normal incidence.
  • the second Floquet port sees mostly the conductive face, one may expect the reflection to be at 180 degrees.
  • FIG. 9A shows the crossed slot 31 is composed of an x-axis slot 28 and a y- axis slot 29.
  • FIG. 9B shows a differential/common mode quarter circuit of the entire circuit when the incident field is y- polarized. The electric field is permitted across the slot along the x axis, but not the y-axis, except at much higher
  • FIGs. lOA-lOC show three configurations for the NFC 38 shown in FIG. 7A that may be used for tuning the AAMC 10.
  • NFCx x-polarized patches
  • NFCy y-polarized patches
  • NFCx and NFCy may be different to achieve different frequencies or other characteristics.
  • all four NFCs 60, 62, 64 and 66 may be different if polarization rotation is desired.
  • Differential quarter-circuit analysis shows that, if symmetry is preserved, NFCx does not affect y- polarized waves and vice versa.
  • the X configuration as shown in FIG. 10B has four identical NFCs 70, 72, 74 and 76, each connected to a respective one of the four corners of patch 30, 32, 34 or 36 near the junction of the cross slots 31.
  • the NFCs 70, 72, 74 and 76 are each connected to a common node 78 in the center of the
  • NFCs - NFC45 80 and NFC135 82 connect diagonal corners of the junction of the crossed slot 31, where NFC45 80 is on a 45 degree angle, and NFC135 82 is on a 135 degree angle.
  • NFC45 80 is connected between corners of patches 32 and 34, and NFC135 82 is connected between corners of patches 30 and 36.
  • the principle axes are rotated 45 degrees.
  • the response to 45 degree polarized waves is dependent on NFC45 80, and the response to 135 degree waves is dependent on NFC135 82.
  • the response is polarization independent if NFC45 80 is the same as NFC135 82.
  • both unit cell designs with d 43 equal to 75mm and d 43 equal to 100mm cover the same frequency range, albeit with different negative inductance loading; however, the 75mm unit cell has a larger bandwidth.
  • the admittance matrix can be simplified to 1/s times an inductance matrix where the eigenvalues of the inductance matrix quantify an equivalent inductance for a given eigenmode. Assuming all NFCs are identical with inductance L NFC less than 0, the total inductance is the parallel combination of the eigenvalue L eq and L NFC ; the network is stable if L NFC is less than -L eq for all eigenvalues. This method may be extended to all frequencies by performing Nyquist analysis on the frequency domain admittance matrix and NFC admittance model.
  • NFC45 80 varying from -45 to - 32 nH and NFC135 82 omitted predicts that the AAMC 10 is stable for L NFC less than -37 nH, which implies that tuning from 1200 MHz to 500 MHz is achievable.
  • An active artificial magnetic conductor includes an array of unit cells, each unit cell including a top face, at least one wall coupled to the top face, a base coupled to the at least one wall, and a crossed slot in the top face.
  • the top face, the at least one wall, and the base form a cavity and are conductive.
  • a base coupled to the at least one wall; and a crossed slot in the top face;
  • the top face has first, second, third and fourth edges; and the at least one wall comprises:
  • the material comprising air, a dielectric material, or a magnetic material.
  • each unit cell is symmetric about an x-z and about a y-z axis;
  • AAMC of concept 1 further comprising:
  • AAMC of concept 2 further comprising:
  • the crossed slot divides the top face into first, second, third, and fourth patches
  • the at least two reactive elements comprise: a first reactive element connected across the crossed slot between the first patch and the second patch;
  • the crossed slot divides the top face into a first, second, third, and fourth patches, each patch having a corner near a junction of the crossed slot;
  • the at least two reactive elements comprise:
  • the crossed slot divides the top face into a first, second, third, and fourth patches, each patch having a corner near a junction of the crossed slot;
  • the at least two reactive elements comprise:
  • corner of the first patch is diagonally across the junction of the crossed slot from the corner of the fourth patch; and wherein the corner of the second patch is diagonally across the junction of the crossed slot from the corner of the third patch .
  • AMC active artificial magnetic conductor
  • a second wall coupled to the second edge of the top face
  • a third wall coupled to the third edge of the top face
  • a fourth wall coupled to the fourth edge of the top face ;
  • the material comprising air, a dielectric material, or a magnetic material.
  • crossed slot divides the top face into first, second, third, and fourth patches
  • AAMC further comprises:
  • crossed slot divides the top face into a first, second, third, and fourth patches, each patch having a corner near a junction of the crossed slot;
  • the AAMC further comprises:
  • corner of the first patch is diagonally across a junction of the crossed slot from the corner of the fourth patch
  • corner of the second patch is diagonally across a junction of the crossed slot from the corner of the third patch .
  • each unit cell is symmetric about an x-z and about a y-z axis
  • the cavity has a square cross section of size slightly less than a period of repetition of the unit cells in the array of unit cells.

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  • Aerials With Secondary Devices (AREA)

Abstract

L'invention concerne un conducteur magnétique artificiel actif qui comprend un réseau de cellules unitaires, chaque cellule unitaire comportant une face supérieure, au moins une paroi couplée à la face supérieure, une base couplée à ladite ou auxdites parois, et une fente croisée dans la face supérieure. La face supérieure, la ou les parois et la base forment une cavité et sont conductrices.
PCT/US2014/072233 2014-02-24 2014-12-23 Conducteur magnétique artificiel actif WO2015126521A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP14882944.3A EP3111509A4 (fr) 2014-02-24 2014-12-23 Conducteur magnétique artificiel actif
CN201480072872.7A CN105900282A (zh) 2014-02-24 2014-12-23 有源人工磁导体

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US14/188,264 2014-02-24
US14/188,225 2014-02-24
US14/188,225 US9379448B2 (en) 2011-04-07 2014-02-24 Polarization independent active artificial magnetic conductor
US14/188,264 US20150244079A1 (en) 2014-02-24 2014-02-24 Cavity-backed artificial magnetic conductor

Publications (1)

Publication Number Publication Date
WO2015126521A1 true WO2015126521A1 (fr) 2015-08-27

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3312935A1 (fr) * 2016-10-24 2018-04-25 The Boeing Company Décalage de phase de réflexions de signaux d'ondes progressives de surface
CN111916890A (zh) * 2019-05-09 2020-11-10 深圳光启尖端技术有限责任公司 一种超材料电扫描天线
US11024952B1 (en) 2019-01-25 2021-06-01 Hrl Laboratories, Llc Broadband dual polarization active artificial magnetic conductor

Citations (5)

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US20080094300A1 (en) * 2006-10-20 2008-04-24 Lee Gregory S Element Reduction In Phased Arrays With Cladding
US20090025973A1 (en) * 2007-07-25 2009-01-29 Samsung Electronics Co., Ltd. Electromagnetic screen
US20100039111A1 (en) * 2006-12-22 2010-02-18 Koninklijke Philips Electronics N. V. Rf coil for use in an mr imaging system
US8451189B1 (en) * 2009-04-15 2013-05-28 Herbert U. Fluhler Ultra-wide band (UWB) artificial magnetic conductor (AMC) metamaterials for electrically thin antennas and arrays
US20130200947A1 (en) * 2010-04-11 2013-08-08 Broadcom Corporation Programmable antenna having metal inclusions and bidirectional coupling circuits

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080094300A1 (en) * 2006-10-20 2008-04-24 Lee Gregory S Element Reduction In Phased Arrays With Cladding
US20100039111A1 (en) * 2006-12-22 2010-02-18 Koninklijke Philips Electronics N. V. Rf coil for use in an mr imaging system
US20090025973A1 (en) * 2007-07-25 2009-01-29 Samsung Electronics Co., Ltd. Electromagnetic screen
US8451189B1 (en) * 2009-04-15 2013-05-28 Herbert U. Fluhler Ultra-wide band (UWB) artificial magnetic conductor (AMC) metamaterials for electrically thin antennas and arrays
US20130200947A1 (en) * 2010-04-11 2013-08-08 Broadcom Corporation Programmable antenna having metal inclusions and bidirectional coupling circuits

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP3111509A4 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3312935A1 (fr) * 2016-10-24 2018-04-25 The Boeing Company Décalage de phase de réflexions de signaux d'ondes progressives de surface
US10116023B2 (en) 2016-10-24 2018-10-30 The Boeing Company Phase shift of signal reflections of surface traveling waves
US10431862B2 (en) 2016-10-24 2019-10-01 The Boeing Company Phase shift of signal reflections of surface traveling waves
US11024952B1 (en) 2019-01-25 2021-06-01 Hrl Laboratories, Llc Broadband dual polarization active artificial magnetic conductor
CN111916890A (zh) * 2019-05-09 2020-11-10 深圳光启尖端技术有限责任公司 一种超材料电扫描天线

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