WO2017123586A1 - Limiteur sélectif de fréquence - Google Patents

Limiteur sélectif de fréquence Download PDF

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Publication number
WO2017123586A1
WO2017123586A1 PCT/US2017/012937 US2017012937W WO2017123586A1 WO 2017123586 A1 WO2017123586 A1 WO 2017123586A1 US 2017012937 W US2017012937 W US 2017012937W WO 2017123586 A1 WO2017123586 A1 WO 2017123586A1
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WO
WIPO (PCT)
Prior art keywords
sections
magnetic material
disposed
slow wave
transmission line
Prior art date
Application number
PCT/US2017/012937
Other languages
English (en)
Inventor
Matthew A. Morton
Gerhard Sollner
Original Assignee
Raytheon Company
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 US14/996,881 external-priority patent/US9711839B2/en
Application filed by Raytheon Company filed Critical Raytheon Company
Priority to CN201780006651.3A priority Critical patent/CN108475835B/zh
Priority to AU2017206716A priority patent/AU2017206716B2/en
Priority to EP17701955.1A priority patent/EP3403293B1/fr
Priority to JP2018536256A priority patent/JP6625226B2/ja
Priority to KR1020187023391A priority patent/KR102132548B1/ko
Publication of WO2017123586A1 publication Critical patent/WO2017123586A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/20—Frequency-selective devices, e.g. filters
    • H01P1/201—Filters for transverse electromagnetic waves
    • H01P1/203—Strip line filters
    • H01P1/2039—Galvanic coupling between Input/Output
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P1/00—Auxiliary devices
    • H01P1/22—Attenuating devices
    • H01P1/23—Attenuating devices using ferromagnetic material

Definitions

  • This disclosure relates generally to frequency selective limiter.
  • a Frequency Selective Limiter is a nonlinear passive device that attenuates signals above a predetermined threshold power level while passing signals below the threshold power level.
  • a key feature of the FSL is the frequency selective nature of the high-power limiting: low power signals close in frequency to the limited signals are unaffected.
  • the FSL acts as a high-Q (>1000 demonstrated) notch filter that automatically tunes to attenuate high power signals within a narrow frequency band as illustrated in FIGS. 1 A, IB and 1C which illustrate the frequency selectivity of a typical YIG FSL; the frequency response of: an input to the FSL being illustrate in FIG. 1 A, the transmission loss through the FSL being illustrated in FIG.
  • the power threshold level is set primarily by the structure of a ferrite material.
  • single-crystal YIG material is a ferrite material that provides a lower power threshold than polycrystalline YIG, which is then lower than hexaferrite materials.
  • ferrite FSLs rely on the non-linear response of a magnetized ferrite material. Above a critical RF magnetic field level the spin precession angle saturates in the ferrite and coupling to higher order spin-waves starts to occur. RF energy fed to the FSL is coupled efficiently to spin-waves at approximately one-half the signal frequency and then converted to heat.
  • the threshold power levels for the onset of limiting range from ⁇ -30 dBm for magnetostatic wave FSLs to >40 dBm for polycrystalline ferrite in subsidiary resonance FSLs.
  • the critical RF magnetic field is directly proportional to the spin-wave linewidth of the ferrite material.
  • Liquid Phase Epitaxy (LPE) Yttrium-Iron-Garnet (YIG) is typically used because it has the narrowest spin-wave linewidth of all measured materials, on the order of 0.2-0.5 Oersted (Oe).
  • a typical implementation of an FSL includes a strip conductor disposed between a pair of ground plane conductors in a stripline microwave transmission structure using two YIG slabs or films for the dielectric, as shown in FIG. 2, to couple the magnetic energy of the interfering signal into the magnetic material.
  • Permanent biasing magnets are mounted to the sides, as shown, or may be mounted to the top and bottom of the structure.
  • the strength of the magnetic field within the structure establishes the operating bandwidth of the limiter.
  • An electro-magnet may be used in which case a wire, not shown, is wrapped around the entire structure to provide windings in a direction perpendicular to the stripline. DC current flows through the windings to provide a bias magnetic field.
  • the bias is selected to establish the operating bandwidth of the limiter.
  • the slab thickness is generally 100 um or less because of the difficulty in growing thick YIG films, requiring stripline widths on the order of 20 um to achieve an input impedance Z 0 matched closely to 50 ohms.
  • This approach is simple to fabricate and provides adequate magnetic fields to realize a critical power level of approximately 0 dBm when using single crystal YIG material.
  • One method of reducing the power level threshold of the FSL is to use a lower input impedance stripline (i.e., less than 50 ohms); however, at the cost of degraded return loss.
  • a lower input impedance stripline i.e., less than 50 ohms
  • an impedance matching structure is sometimes used to improve the impedance match; however, this technique reduces the bandwidth and increases the insertion loss of the FSL; the approach reduces the resistive losses associated with the transmission structure for weak signals, and slightly increases the magnetic coupling of the signals with the ferrite material.
  • the present disclosure is directed to a frequency selective limiter having a combination of magnetic material and dielectric material.
  • the dielectric material has a lower relative permittivity or relative dielectric constant, er, than the magnetic material, which results in an enhanced microwave transmission line.
  • this design improves an overall frequency selective limiter (FSL) performance by increasing the local magnetic interaction of the signal with the magnetic material, thereby achieving a lower threshold for the onset of the desired nonlinear behavior.
  • the FSL may be implemented in any strip conductor configuration including but not limited to a microstrip configuration, a stripline configuration or a co-planar configuration.
  • the present disclosure also enables the use of lower-cost materials (e.g. polycrystalline instead of single-crystal YIG), with significantly reduced complexity associated with manufacturing. Further, the insertion loss remains low with the proposed structure and the FSL performance parameters can be tuned via design changes in the transmission line structure rather than modifying material properties of the dielectric material.
  • a slow wave FSL structure can be fabricated using common manufacturing techniques without requiring micromachining or etching of the magnetic materials, thereby resulting in a low cost solution.
  • the present disclosure is directed towards a slow wave structure having a combination of a dielectric material disposed about a magnetic material to magnetically couple a magnetic field, produced by electromagnetic energy propagating through the slow wave structure, into the magnetic material.
  • the slow wave structure has an input impedance Z 0 and the impedances may periodically change from an impedance greater than Z 0 to an impedance less than Z 0 as the electromagnetic energy propagates through the slow wave structure.
  • the present disclosure is directed towards a combination of a magnetic material, a dielectric material disposed about the magnetic material and a slow wave structure disposed to magnetically couple a magnetic field, produced by
  • the slow wave structure is a transmission line having an input impedance, Z 0.
  • the transmission line includes a first transmission line section disposed between a pair of second transmission line sections.
  • the first transmission line section has an impedance Z H higher than Z 0 and the pair of second transmission line sections have an impedance lower than Zo.
  • the first transmission line section and the pair of second transmission line sections each have a length shorter than a nominal operating wavelength of the electromagnetic energy propagating through the slow wave structure.
  • the present disclosure is directed towards a combination including a magnetic material, a dielectric material disposed about the magnetic material and a slow wave structure disposed to magnetically couple a magnetic field, produced by electromagnetic energy propagating through the slow wave structure, into the
  • the slow wave structure is a transmission line having a first transmission line section disposed between a pair of second transmission line sections.
  • the first transmission line section and the pair of second transmission lines sections include a strip conductor and at least one ground plane conductor.
  • the magnetic material may be disposed between the strip conductor and the at least one ground plane conductor.
  • the strip conductor includes a first strip conductor section disposed between a pair of second strip conductor sections.
  • the first strip conductor section may be separated from a portion of the ground plane conductor disposed over the first strip conductor section a first distance Dl .
  • the pair of second strip conductor sections are separated from portions of the ground plane conductor disposed over the pair of second strip conductor sections a second distance D2, where Dl and D2 are different distances.
  • the present disclosure is directed towards a combination including a magnetic material, a dielectric material disposed about the magnetic material and a slow wave structure disposed to magnetically couple a magnetic field, produced by electromagnetic energy propagating through the slow wave structure, into the
  • the slow wave structure is a transmission line having a first transmission line section disposed between a pair of second transmission line sections.
  • the first transmission line section and the pair of second transmission lines sections include a strip conductor and a pair of ground plane
  • the strip conductor includes a first strip conductor section and a pair of second strip conductor sections with the first strip conductor section disposed between the pair of second strip conductor sections.
  • the first strip conductor section is separated from a portion of the pair of ground plane conductors disposed over and under the first strip conductor section a first distance Dl .
  • the pair of second strip conductor sections may be separated from portions of the ground plane conductor disposed over and under the pair of second strip conductor sections a second distance D2, where Dl and D2 are different distances.
  • the present disclosure is directed towards a frequency selective limiter.
  • the frequency selective limiter includes a first layer of a dielectric material having first and second opposing surfaces and a first layer of magnetic material having first and second opposing surfaces.
  • the second surface of the first layer of the dielectric materials is disposed over the first surface of the first magnetic material and the dielectric material has a lower relative permittivity than the magnetic material.
  • a strip conductor is disposed over the first layer of magnetic material.
  • the frequency selective limiter includes a second layer of the dielectric material having first and second opposing surfaces and a second layer of magnetic material having first and second opposing surfaces.
  • the first surface of the second layer of the dielectric materials is disposed over the second surface of the second magnetic material and the strip conductor is disposed between the first and second layer of magnetic material.
  • the combination of the first and second layers of dielectric material and the first and second layers of magnetic material include a slow wave structure having an input impedance Z 0 .
  • the impedances may periodically change from an impedance greater than Z 0 to an impedance less than Zo as an electromagnetic energy propagates through the slow wave structure.
  • the frequency selective limiter includes a first and second ground plane. The first ground plane is disposed over the first surface of the first layer of dielectric material and the second ground plane is disposed over the second surface of the second layer of dielectric material.
  • the frequency selective limiter may include a first set of conducting pads disposed between the first layer of the dielectric materials and the magnetic material and a second set of conducting pads disposed between the second layer of the dielectric materials and the second magnetic material.
  • a first set of vias is disposed within the first layer of dielectric material and a second set of vias is disposed within the second layer of dielectric material.
  • the first set of vias couple the first ground plane to the first set of conducting pads and the second set of vias couple the second ground plane to the second set of conducting pads to form alternating sections of low impedance stripline sections and high impedance stripline sections within the slow wave structure.
  • the alternating sections of low impedance stripline sections and high impedance stripline sections couple magnetic energy propagating through the slow wave structure and into that the first and second magnetic layers.
  • the magnetic energy may have a power level above a predetermined power threshold.
  • the frequency selective limiter is a transmission line having an input impedance, Z 0 .
  • the transmission line includes a first transmission line section disposed between a pair of second transmission line sections. The first
  • the transmission line section may have an impedance Z H higher than Z 0 and the pair of second transmission line sections have an impedance Z L lower than Z 0 .
  • the first transmission line section and the pair of second transmission lines sections each have a length shorter than a nominal operating wavelength of electromagnetic energy propagating through the slow wave structure.
  • the present disclosure is directed towards a frequency selective limiter.
  • the frequency selective limiter includes a magnetic material to magnetically couple a magnetic field, produced by electromagnetic energy propagating through the slow wave structure, into the magnetic material and a dielectric layer disposed over the magnetic material.
  • the dielectric layer has a lower relative permittivity than the magnetic material.
  • the slow wave structure may have an input impedance Z 0 and the impedances may periodically change from an impedance greater than Zo to an impedance less than Z 0 as the electromagnetic energy propagates through the slow wave structure.
  • a ground plane is disposed over a first surface of the dielectric layer.
  • a set of conducting pads may be disposed between the dielectric layer and the magnetic material.
  • a set of vias may be disposed within the dielectric layer.
  • the set of vias couple the ground plane to the set of conducting pads to form alternating sections of low impedance striplines and high impedance striplines within the slow wave structure.
  • the alternating sections of low impedance striplines and high impedance striplines couple the electromagnetic energy propagating through the slow wave structure and into the magnetic material.
  • the present disclosure is directed towards a frequency selective limiter including a first and second layer of a dielectric material, each having first and second opposing surfaces.
  • the frequency selective limiter further includes a first and second layer of magnetic material, each having first and second opposing surfaces.
  • the second surface of the first layer of the dielectric materials is disposed over the first surface of the first magnetic material and the first surface of the second layer of the dielectric materials is disposed over the second surface of the second magnetic material.
  • the dielectric material has a lower relative permittivity than the magnetic material.
  • a strip conductor may be disposed between the first and second layer of magnetic material.
  • the slow wave structure is a transmission line having an input impedance, Z 0 and the transmission line includes a first transmission line section and a pair of second transmission line sections, and the first transmission line section has an impedance Z H higher than Z 0 and the pair of second transmission line sections have an impedance lower than Z 0 .
  • the impedances periodically change from an impedance greater than Zo to an impedance less than Zo as an electromagnetic energy propagates through the slow wave structure.
  • the frequency selective limiter includes a first and second ground plane.
  • the first ground plane is disposed over the first surface of the first layer of dielectric material and the second ground plane is disposed over the second surface of the second layer of dielectric material.
  • a first set of conducting pads may be disposed between the first layer of the dielectric materials and the magnetic material and a second set of conducting pads disposed between the second layer of the dielectric materials and the second magnetic material.
  • a first set of vias is disposed within the first layer of dielectric material and a second set of vias is disposed within the second layer of dielectric material.
  • the first set of vias couple the first ground plane to the first set of conducting pads and the second set of vias couple the second ground plane to the second set of conducting pads to form alternating sections of low impedance striplines and high impedance striplines within the slow wave structure.
  • the first transmission line section and the pair of second transmission lines sections each have a length shorter than a nominal operating wavelength of electromagnetic energy propagating through the slow wave structure.
  • the inventors have recognized that while slow wave structures (SWS) have been used to produce larger time delays for the same physical length, they exploit the property of the SWS in producing locally-strong magnetic fields.
  • the structure creates locally-strong magnetic coupling, thereby decreasing the effective power threshold via electrical design rather than modification to the material properties.
  • the inventors increase the magnetic interaction of the microwave signals with the magnetic, e.g., YIG substrate, thereby reducing the effective power threshold of when nonlinearity occur and thereby achieves a lower threshold for the onset of the desired nonlinear behavior.
  • the strip conductor includes a first strip conductor section disposed between a pair of second strip conductor sections, and wherein the first strip conductor section is separated from a portion of the pair of ground plane conductors disposed over and under the first strip conductor section a first distance Dl, and wherein the pair of second strip conductor sections are separated from portions of the ground plane conductor disposed over and under the pair of second strip conductor sections a second distance D2, where Dl and D2 are different distances.
  • the strip conductor width has been set to a constant that minimizes small-signal insertion loss, and the impedance is set by varying the vertical distance of the ground planes using conductive vias.
  • the limiter is matched to 50 .0 ⁇
  • the numerous low-impedance sections of the slow wave structure couple significantly higher magnetic energy into the magnetic material, locally reducing the power threshold. This reduces the total effective power threshold, without also degrading the return loss or instantaneous bandwidth of the device.
  • the strip conductor width is been set to a constant that minimizes small-signal insertion loss, and the impedance is set by varying the vertical distance of the ground planes using conductive vias.
  • the complete FSL component is matched to 50 ⁇
  • the numerous low-impedance sections of the slow wave structure couple significantly higher magnetic energy into the material, locally reducing the power threshold. This reduces the total effective power threshold, without also degrading the return loss or instantaneous bandwidth of the device.
  • each segment is much less than a wavelength ( ⁇ , where ⁇ is the nominal operating wavelength of the slow wave structure) (in practice, ⁇ ( ⁇ )/10, but the smaller the better).
  • ⁇ the nominal operating wavelength of the slow wave structure
  • the effective impedance of the entire transmission line structure is the square root of the product of the two impedances. This is why it is desired the product be Zo 2 .
  • a structure could have 100 ohm and 25 ohm impedance segments; however, 10 ohms and 250 ohms, or even 5 ohms and 500 ohms, may be preferred.
  • the FSL performance parameters can be tuned via design changes in the transmission line structure rather than optimize material properties of the dielectric.
  • the power threshold is now a function of both the material properties and of the transmission line structure. Because the slow wave structure features stronger magnetic coupling into the magnetic material, the effective threshold of power is lower because less RF power is needed to achieve the same magnetic field strength.
  • An additional benefit is the ability to design for a specific threshold power. It is much easier to design a slow wave structure to provide a specific magnetic field strength (hence threshold power level, PTH) than it is to tune the material properties of the magnetic material.
  • the helical slow wave structure has been used as a slow wave structure in TWTAs (traveling wave tube amplifiers) to slow the RF signal down such that the speed is the same as electrons that are traveling down the length of the tube through the center of the helical so that the electrons generated from an electron gun terminate on the other side of the tube and that because the electrons and RF signals are traveling at the same speed, they interact and the intensity of the RF signal is increased as it propagates down the coil; the inventors have recognized the helical structure can be used intensify the magnetic coupling of the RF signal with a magnetic material at the center or core of the helical to now, instead of interacting with the electron beam, interacts with the magnetic material and that this interaction will causes spinwaves which dissipate heat in the crystal structure of the magnetic material at half the frequency of the RF signal to attenuate the signal. These spinwaves dissipate the energy as heat.
  • TWTAs traveling wave tube amplifiers
  • FIGS. 1 A, IB and 1C illustrate the frequency response of an Frequency Selective Limiter (FSL) according to the PRIOR ART;
  • FIG. 1 A showing the frequency spectrum of an input signal to the FSL;
  • FIG IB showing the transmission loss through the FSL, it being noted that there is significant attenuation to the frequency components in the input signals having power levels above the predetermined power threshold level, PTH (FIG. 1 A) while the frequency components in the input signals having power levels below the predetermined power threshold level, P TH pass through the FSL unattenuated (except for by the small signal losses (resistive losses, impedance mismatch, etc.); and
  • FIG. 1 C showing the output power spectra of the FSL for multiple weak and strong signals;
  • FIG 2 shows an FSL according to the PRIOR ART
  • FIG. 3 is an exploded, isometric view of an FSL according to the disclosure.
  • FIGS. 4 and 4A are diagrammatical isometric and cross sectional views, respectively, of an FSL according to another embodiment of the disclosure.
  • FIGS. 5A-5E are different views of an FSL according to still another embodiment of the disclosure
  • FIG. 5A being a cross sectional view of a FSL having a helical slow wave structure formed on a magnetic substrate, the substrate having a helical coil conductor disposed around it, the substrate being bonded to a dielectric slab, the dielectric slab having a metal trace to provide a ground conductor for the FSL structure
  • FIG. 5B being a plan view of a top of the magnetic substrate
  • FIG. 5C being a plan view of a bottom plan of the magnetic substrate
  • FIG. 5D being a plan view of bottom of the lower dielectric slab
  • FIG. 5A being a cross sectional view of a FSL having a helical slow wave structure formed on a magnetic substrate, the substrate having a helical coil conductor disposed around it, the substrate being bonded to a dielectric slab, the dielectric slab having a metal trace to provide a ground conductor for the FSL structure
  • FIG. 5B being
  • FIG. 5E being a diagrammatical isometric of the FSL having the helical slow wave structure of FIGS. 5A-5D; and wherein the cross section of FIG. 5 A is taken along line 5A-5A n FIG. 5D, the top view of FIG. 5B being designated by the line 5B-5B in FIG. 5 A, the bottom view of FIG. 5C being indicated by the line 5C-5C in FIG. 5 A, and the bottom view of FIG. 5D being indicated by the line 5D-5D in FIG. 5 A;
  • FIG. 6 is a cross-sectional view of an FSL having a microstrip transmission line according to another embodiment of the disclosure.
  • FIG. 7 is an end view of an FSL having a stripline transmission line according to another embodiment of the disclosure.
  • FIG. 7A is a cross-sectional view of an FSL taken across lines 7A-7A in Fig. 7.
  • the limiter 10 is a slow wave structure comprising a stripline microwave transmission line having a series of different impedances Z H I G H and Z L ow from an INPUT of the limiter 10 to an OUTPUT of the limiter 10. More particularly, the limiter 10 includes a pair magnetic members, slabs 12, 14, here, for example, ferrimagnetic slabs, such as, for example, YIG slabs, 12, 14, having a strip conductor 16 sandwiched between the slab and ground plane conductors 18, 20 on the outer surface of the magnetic slabs 12, 14, as shown. The strip conductor 16 varies in width between a narrow width sections 16N and wider width sections 16W, as shown.
  • the slow wave structure 10 has in input impedance Z 0 of 50 ohms; the narrow section 16N providing impedances of here for example, 250 ohms and the wider sections 16W providing here for example, 10 ohms.
  • the length of each section is less than the nominal operating wavelength of the
  • the impedance of each section is established by the width of the strip conductor of such section.
  • the size and spacing of the wide and narrow section 16N and 16W provide the slow wave structure with the input impedance Z 0 of 50 ohms.
  • the impedances of the narrow sections and wider sections 16N and 16W here periodically change from an impedance greater than Z 0 to an impedance less than Z 0 as the electromagnetic energy propagates through the slow wave structure 10.
  • a conventional pair of bias magnets, 1 1 here permanent magnets, for example, are mounted to the sides of the structure.
  • the permanent biasing magnets 11 may be mounted to the top and bottom of the structure. The strength of the magnetic field within the structure establishes the operating bandwidth of the limiter.
  • An electro-magnet may be used in which case a wire, not shown, is wrapped around the entire structure to provide windings in a direction perpendicular to the stripline. DC current flows through the windings to provide a bias magnetic field.
  • the bias is selected to establish the operating bandwidth of the limiter.
  • the slow wave structure 10 couples the magnetic energy of the input interfering signal that has higher power level (a power level above the predetermined FSL power threshold PTH) of the slow wave structure 10 into the magnetic material of the magnetic slabs 12, 14.
  • the slow wave structure 10 is used to magnetically couple a magnetic field, produced by electromagnetic energy propagating through the slow wave structure, into the magnetic slabs 12, 14.
  • the limiter 10' is a slow wave structure comprising a stripline microwave transmission line having a series of different impedances Z HI G H and ZL O W from an INPUT of the limier 10' to an OUTPUT of the limiter 10'. More particularly, the limiter 10' includes a two pairs magnetic slabs 12a, 12b, and 14a, 14b, having a strip conductor 16 sandwiched between the slabs and ground plane conductors 18, 20 on the outer surface of the ferrimagnetic slabs 12a and 14a, as shown.
  • a magnetic material here for example, a ferrimagnetic slab 12a
  • a ferrimagnetic slab 12a has a ground plane conductor 18 on its outer surface and a series of conductive pads 21 laterally spaced by regions 27a on its inner surface, as shown.
  • the conductive pads 12 are connected to the ground plane conductor 18 by conductive vias 22 passing through the slab 12a between the conductive pads 21 and the ground plane conductor 18, as shown.
  • the ferromagnetic slab 12b Disposed between the upper surface of the strip conductor 16 and the conductive pads 21 is the ferromagnetic slab 12b, as shown.
  • magnetic slab 14a here, also, for example, a ferrimagnetic slab, has a ground plane conductor 20 on its outer surface and a series of conductive pads 23 laterally spaced by regions 27b on its inner surface, as shown.
  • the conductive pads 23 are connected to the ground plane conductor 20 by conductive vias 25 passing through the slab 14a between the conductive pads 23 and the ground plane conductor 20, as shown.
  • ferrimagnetic slab 14b Disposed between the bottom surface of the strip conductor 16 and the conductive pads 23 is the ferrimagnetic slab 14b, as shown.
  • the distance Dl between the conductive pads 21 , 23, (and hence, in effect, the electrically connected ground plane conductors 18, 20) respectively, and the strip conductor 16 is greater that the distance D2 between the strip conductor 16 and the ground plane conductors 18, 20 in the regions 27a, 27b.
  • the impedance in the regions 27a, 27b Z H IGH is greater than the impedance Z L ow in the regions having the conductive pads 21 , 23.
  • the slow wave structure 10' has in input impedance Z 0 of 50 ohms; the regions 27a, 27b providing impedances of here for example, 250 ohms and the regions through the conductive pads 21 , 23 providing here for example, 10 ohms.
  • the size and distance Dl , D2 provide the slow wave structure with the input impedance Z 0 of 50 ohms.
  • the impedances of again periodically change from an impedance greater than Z 0 to an impedance less than Z 0 as the electromagnetic energy propagates through the slow wave structure 10'.
  • the impedance of each section is established by the distance Dl and D2.
  • width of the strip conductor 16 is set to a constant that minimizes small-signal insertion loss, and the impedance is set by varying the vertical distance of the ground planes 18, 20 using vias 22. While the complete FSL component is matched to 50 ⁇ , the numerous low-impedance sections of the slow wave structure couple significantly higher magnetic energy into the ferrimagnetic slabs, locally reducing the P TH power threshold. This reduces the total effective power threshold, without also degrading the return loss or instantaneous bandwidth of the device. Referring now to FIGS. 5A-5E, another embodiment of an FSL is shown.
  • the FSL is a helical slow wave structure 10' having a magnetic body 30 made of a magnetic, here ferrimagnetic (e.g., YIG) substrate 30, as shown).
  • the substrate 30 provides a magnetic core, for a helical conductor or coil 32.
  • the helical conductor 32 is used to create a strong magnetic field within the ferrimagnetic material center, or core 30 due to reinforcement from adjacent turns in the coil 32.
  • the coil 32 is implemented with conductive vias 34 to connect the top side of the coil 32 to the bottom side of the coil 32. Since the magnetic field outside of the coil is relatively small, it may not be beneficial to have additional magnetic, for example, YIG substrates (not shown), outside of the coil structure 32.
  • the ground reference for the coil includes a metal trace 36 defined on the bottom side of a supporting dielectric slab 38.
  • the dielectric slab 38 is bonded to the bottom of the magnetic body 30, whereby the supporting dielectric is attached to the ferrimagnetic core (or substrate) containing the coil 32.
  • the dielectric material of dielectric slab 38 is a non-magnetic material such as FR-4 or a Rogers Corporation, Rogers, CT laminate material.
  • the lowest critical fields are achieved when the static and RF induced magnetic fields are parallel.
  • bias magnets 11 here permanent magnets
  • the strength of the magnetic field within the structure establishes the operating bandwidth of the limiter.
  • the coil structure is oriented perpendicular to the axial direction of the magnetic field produced by the magnets 11.
  • the permanent magnets 1 1 are disposed on either end of the coil rather than along the sides or the top and bottom.
  • a frequency selective limiter 40 includes a magnetic material 42 disposed over a dielectric material 44 which in turn is disposed over a ground plane 50.
  • Magnetic material 42 has first and second opposing surfaces 42a, 42b and dielectric material 44 also has first and second opposing surfaces 44a, 44b.
  • the second surface 42b of magnetic material 42 disposed over the first surface 44a of dielectric material 44.
  • a strip conductor 46 is disposed over the first surface 42a of magnetic material 42 such that ground plane 50, dielectric material 44 and magnetic material 42 form a microstrip transmission line structure.
  • dielectric material 44 has a lower relative permittivity or relative dielectric constant, ⁇ ⁇ , than magnetic material 42.
  • magnetic material 42 may be provided as a ferromagnetic material, such as Yttrium iron garnet (YIG), and dielectric material 44 may be provided as a non-magnetic material, such as FR- 4 laminate material or a Rogers Corporation, Rogers, CT laminate material (e.g., RO 4003 laminates).
  • YIG Yttrium iron garnet
  • CT laminate material e.g., RO 4003 laminates
  • Other materials having similar mechanical and electrical properties may of course, be used.
  • magnetic material 42 may be provided as single crystal YIG, polycrystalline YIG, hexaferrite YIG or a variety of doped YIG materials.
  • dielectric material 44 may include any material having a low relative permittivity (i.e., a relative dielectric constant of less than 4). In some embodiments, dielectric material 44 may be provided as alumnia or low- temperature co-fired ceramics (LTCC).
  • LTCC low- temperature co-fired ceramics
  • Conductive vias 54a-54x may be disposed through dielectric material 42 and at least electrically couple ground plane 50 to a first set of conductive pads 52 disposed between second surface 42a of magnetic material 42 and first surface 44a of dielectric material 44. Conductive vias 54a-54x may be spaced a predetermined distance from a neighboring or adjacent conductive via 54. In an embodiment, each conductive via 54a- 54x is aligned with at least one conductive pad 52. In embodiments, conductive vias 54a- 54x may be formed such that they are perpendicular to a plane in which lie ground plane 50 and strip conductor 46.
  • a region 56 is formed between each conductive pad 52.
  • Region 56 may include portions of dielectric material 44 that have reflowed into the gaps (i.e., regions 56) formed between each conductive pad 52 during fabrication.
  • region 56 includes an adhesive material that bonds dielectric material 44 to magnetic material 42.
  • the adhesive material may be provided as a lower melting temperature version of the same material provided in dielectric material 44.
  • region 56 may be provided as a different dielectric medium than the material provided in dielectric material 44.
  • each of the conductive pads 52 may include an adhesive material disposed over at least one surface to adhere each conductive pad 52 to magnetic material 42.
  • the adhesive material may be formed in a very thin layer over conductive pad 52, (e.g., thickness in the range of about 0.5 mil to about 2 mil). It should be appreciated that one of ordinary skill in the art will understand how to adhere dielectric layer 44 to the magnetic material layer, once a particular set of materials is selected.
  • Conductive vias 54a-54x may operate as a ground plane for low impedance portions within frequency selective limiter 40.
  • conductive vias 54a-54x form alternating sections of low impedance and high impedance microstrip transmission lines within frequency selective limiter 40.
  • the number of low impedance sections in frequency selective limiter 40 is equal to the number of high impedance sections.
  • the characteristic impedance of a particular system establishes an impedance threshold between a low impedance section and a high impedance section.
  • a section having an impedance less than the characteristic impedance of the system can be a low impedance section and a section having an impedance greater than characteristic impedance of the system can be a high impedance section.
  • a low impedance section refers to a section having an impedance less than 50 ohms.
  • a high impedance section refers to a section having an impedance greater than 50 ohms.
  • frequency selective limiter 40 is a slow wave structure having a microstrip microwave transmission line and having a series of different impedances Z H I G H and ZLOW from an INPUT of frequency selective limiter 40 to an OUTPUT of frequency selective limiter 40.
  • a pair of neighboring or adjacent sections form a unit cell.
  • the spacing between each unit cell may be the same or substantially similar.
  • each unit cell may be of equal length and width.
  • the lengths and widths of the unit cells may be selected based upon a particular operating frequency or range of operating frequencies of frequency selective limiter 40.
  • each unit cell may have a length of about 40 mil, which provides useful operation up to a frequency of about 5 GHz.
  • each unit cell may have a length of about 20 mil, which provides useful operation up to a frequency of about 10 GHz.
  • a length (i.e., a dimension parallel to a length of strip conductor 46) of each conductive pad 52 may be equal to or about half the length of its corresponding unit cell.
  • the respective conductive pad 54 would have a length of about 10 mil.
  • Each conductive pad 52 may be provided having a width (i.e., a dimension perpendicular to a length of strip conductor 46) that is wide enough to support a microstrip (or stripline) transmission line mode.
  • a width i.e., a dimension perpendicular to a length of strip conductor 46
  • each conductive pad 52 may be provided having a width (i.e., a dimension perpendicular to a length of strip conductor 46) that is wide enough to support a microstrip (or stripline) transmission line mode.
  • conductive pad 52 may be provided having a width that is at least three times a distance between the respective conductive pad 52 and strip conductor 46.
  • a width e.g., a dimension along a plane parallel to the plane in which first set of conductive pads 52 is disposed between second surface 42a of magnetic material 42 and first surface 44a of dielectric material 44
  • each of the conductive vias 54a-54x may be provided such that it is less than a smallest dimension of the corresponding conductive pad 52 (i.e., length or width).
  • each of the conductive pads 52 have the same or substantially similar dimensions and each of the conductive vias 54a-54x have the same or substantially similar dimensions, thus frequency selective limiter 40 may be provided as a generally symmetric structure.
  • the impedance within frequency selective limiter 40 may be set or controlled by varying a vertical distance between a ground plane and strip conductor 46. For example, a distance, Dl , between conductive pad 52 (i.e., acting as a ground plane to which conductive pad 52 is coupled to) to strip conductor 46 is less than a distance, D2, between ground plane 50 and strip conductor 46 in regions 56 where no conductive via 54 is disposed. Thus, an impedance in regions 56, Z H IGH, is greater than the impedance, ZLOW, in regions having conductive pads 52.
  • the alternating sections of low impedance microstrip lines and high impedance microstrip lines couple magnetic energy propagating through the slow wave structure and into magnetic material 42.
  • magnetic energy having a power level above or equal to a predetermined power level threshold of frequency selective limiter 40 is coupled into magnetic material 42.
  • a combination of magnetic material 42 and dielectric material 44 in frequency selective limiter 40 increases the magnetic coupling of magnetic energy into magnetic material 42.
  • multiple low- impedance microstrip transmission lines couple significantly higher magnetic energy into magnetic material 42, thus reducing a total effective power threshold.
  • a frequency selective limiter 60 includes a pair of magnetic materials 62, 63 disposed about a strip conductor 66 and a pair of dielectric materials 64, 65 with a first one of the dielectric materials 64, 65 disposed over a first one of the magnetic materials 62, 63 and a second one of the dielectric materials 64, 65 disposed over a second one of the magnetic materials 62, 63.
  • frequency selective limiter 60 is provided as a multi-layer frequency selective limiter structure having a stripline transmission line structure.
  • strip conductor 66 is disposed between surface 62b of the first magnetic material 62 and surface 63 a of the second magnetic material 63.
  • a second surface 64b of first dielectric material 64 is disposed over a first surface 62a of first magnetic material 62.
  • a first ground plane 70a is disposed over a first surface 64a of second dielectric material 64.
  • a second surface 63b of second magnetic material 63 is disposed over a first surface 65a of second dielectric material 65.
  • a second surface 65b of dielectric material 65 is disposed over a second ground plane 70b.
  • frequency selective limiter 60 includes two sets of conducting pads 72, 73. Each set disposed may be disposed between magnetic material 62, 63 and dielectric material 64, 65. For example, and as illustrated in FIG. 7, a first set of conductive pads 72 are disposed between second surface 64b of dielectric material 64 and first surface 62a of magnetic material 62. Further, a second set of conductive pads 73 are disposed between second surface 63b of magnetic material 63 and first surface 65a of dielectric material 65. [0070] As may be most clearly seen in FIG. 7A, two sets of conductive vias 74a-74d, 75a-75d are disposed through respective ones of dielectric material layers 64, 65.
  • Respective ones of conductive vias 74a -74d, 75a-75d electrically couple respective ones of pads 72a-72d and 73a-73d to respective ones of ground planes70a, 70b.
  • a vertical distance between ground planes 70a, 70b and strip conductor 66 may be controlled.
  • frequency selective limiter 60 is a slow wave structure having a stripline microwave transmission line having a series of different impedances Z H IGH 78 and ZLOW 76 from an input of frequency selective limiter 60 to an OUTPUT of frequency selective limiter 60.
  • the alternating sections of low impedance striplines 76 and high impedance striplines 78 couple magnetic energy propagating through the slow wave structure and into the pair of magnetic materials 62, 63.
  • alternating (i.e., periodic) segments having very low characteristic impedance e.g., low impedance striplines 76 having an impedance less than a system characteristic impedance
  • a magnetic interaction of signals with magnetic materials 62, 63 is increased.
  • the combination of magnetic material 62, 63 and dielectric material 64, 65 may couple higher magnetic field into magnetic material 62, 63 in low impedance stripline sections 76.
  • an effective power threshold of when nonlinearity occurs for frequency selective limiter 60 is reduced.
  • frequency selective limiter 60 by lowering the power level required to cause nonlinear behavior, frequency selective limiter 60 provides protection for even lower levels of input power.
  • an interfering signal of about 5 dBm may still cause problems.
  • frequency selective limiter 60 with a reduced power threshold level of about 0 dBm would provide protection against the same 5 dBm interfering signal.
  • a width of the strip conductor 66 is set to a constant that reduces (and ideally minimizes) small-signal insertion loss, and the impedance is set by varying the vertical distance of the ground planes 70a, 70b and hence the length of the conductive vias 74a-74d, 75a-75d.
  • first and second ground planes 70a, 70b are closer to strip conductor 66 (providing higher capacitance thus lower impedance) and in high impedance striplines 78, first and second ground planes 70a, 70b are farther away from center strip conductor 66 and have an effective dielectric constant (a function of the combination of magnetic material 62, 63 and dielectric material 64, 65) that is lower thus providing a higher impedance.
  • Impedances at input and output ports of the frequency selective limiter 60 may be matched to a desired characteristic impedance (e.g. a characteristic impedance of a system in which the FSL is included such as a 50 ⁇ characteristic impedance).
  • a desired characteristic impedance e.g. a characteristic impedance of a system in which the FSL is included such as a 50 ⁇ characteristic impedance.
  • the numerous low-impedance sections of the slow wave structure couple significantly higher magnetic energy into magnetic material 62, 63, locally reducing the power threshold (PTH).
  • PTH power threshold
  • the FSL structures described herein are capable of both reducing the total effective power threshold, without also degrading the return loss or instantaneous bandwidth of the device.
  • frequency selective limiter 60 is formed having two layers of 100 ⁇ thick polycrystalline YIG as magnetic material 62, 63 and two layers of 60 mil thick Rogers 4003 as dielectric material 64, 65.
  • First ground plane 70a is disposed over first surface 64a of first dielectric material 64.
  • Second surface 64b of first dielectric material 64 is disposed over first surface 62a of first magnetic material 62.
  • Strip conductor 66 is disposed between second surface 62a and first surface 63 a of second magnetic material 63.
  • Second surface 63b of second magnetic material 63 is disposed over first surface 65a of second dielectric material 65.
  • Second dielectric material 65 is disposed over second ground plane 70b.
  • a twenty (20) ohm section of transmission line is provided from a strip conductor having a width of about 175 ⁇ (i.e., Z L ow 76) when the YIG ground planes (i.e., conducting pads 72, 73) are used, while a 50 ⁇ wide stripline conductor (i.e., Z H I G H 78) achieves a 120 ohm impedance when the ground planes 70a, 70b on the outside portions of dielectric materials 64, 65 (e.g., Rogers material) is used.
  • stripline segment lengths 76, 78 are formed to be
  • stripline segment lengths 76, 78 are formed to be less than 1/10 of a wavelength ( ⁇ (1/10)( ⁇ ) at a maximum frequency of operation), which results in a 49 ohm characteristic impedance and a slow wave factor of 1.43.
  • ⁇ (1/10)( ⁇ ) at a maximum frequency of operation a wavelength at a maximum frequency of operation
  • an increased magnetic field intensity produced by the low impedance segments 76 decreases the frequency selective limiter's 60 power threshold by activating spin waves in dielectric material 64, 65 (i.e., YIG material) at an earlier onset that if a 50 ohm line had been used.
  • conductive vias 74, 75 and ground planes 70a, 70b may be formed by fabricating on or within dielectric material 64, 65, thus no micromachining or etching of dielectric material 64, 65 is required.
  • the high and low impedance lines may be by varied using both the ground plane height and the width of the center conductor line.
  • the ground plane reference in the helical slow wave embodiment, could be manifested by placing the coil inside a metal container shield with air or dielectric gaps between the coil and the metal shield.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Abstract

La présente invention concerne un limiteur sélectif de fréquence ayant un premier matériau magnétique (42) disposé sur un premier matériau diélectrique (44) et un conducteur en bande (46, 66) disposé sur le matériau magnétique. Selon certains modes de réalisation, le limiteur sélectif de fréquence comprend un second matériau magnétique disposé sur le conducteur en bande et un second matériau diélectrique disposé sur le second matériau magnétique. Les premier et second matériaux diélectriques peuvent présenter une permittivité relative inférieure à celle des premier et second matériaux magnétiques. Selon un mode de réalisation, le limiteur sélectif de fréquence comprend une structure à ondes lentes disposée pour coupler magnétiquement un champ magnétique, produit par l'énergie électromagnétique se propageant à travers la structure à ondes lentes, dans le matériau magnétique.
PCT/US2017/012937 2016-01-15 2017-01-11 Limiteur sélectif de fréquence WO2017123586A1 (fr)

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CN201780006651.3A CN108475835B (zh) 2016-01-15 2017-01-11 频率选择限制器
AU2017206716A AU2017206716B2 (en) 2016-01-15 2017-01-11 Frequency selective limiter
EP17701955.1A EP3403293B1 (fr) 2016-01-15 2017-01-11 Limiteur sélectif de fréquence
JP2018536256A JP6625226B2 (ja) 2016-01-15 2017-01-11 周波数選択リミッタ
KR1020187023391A KR102132548B1 (ko) 2016-01-15 2017-01-11 주파수 선택성 리미터

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US14/996,881 US9711839B2 (en) 2013-11-12 2016-01-15 Frequency selective limiter
US14/996,881 2016-01-15

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EP3138643A1 (fr) * 2015-08-20 2017-03-08 The Boeing Company Systèmes et procédés de fabrication d'additif destinés à des matériaux magnétiques
CN108155888A (zh) * 2018-01-05 2018-06-12 北京航天微电科技有限公司 一种用于抑制电源电磁干扰的ltcc大功率emi滤波器
WO2019171769A1 (fr) * 2018-03-06 2019-09-12 国立大学法人大阪大学 Filtre passe-bande
EP3771027A1 (fr) * 2019-07-24 2021-01-27 Rockwell Collins, Inc. Limiteur sélectif à fréquence réglable
JP2021515505A (ja) * 2018-06-26 2021-06-17 レイセオン カンパニー 二平面テーパ化線路周波数選択性リミッタ
CN116886062A (zh) * 2023-07-26 2023-10-13 北京星英联微波科技有限责任公司 高阻表面波导限幅器

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US10608310B1 (en) * 2019-08-02 2020-03-31 Raytheon Company Vertically meandered frequency selective limiter
CN111082194B (zh) * 2019-10-30 2021-07-02 西安电子科技大学 一种具有慢波效应的基片集成槽间隙波导传输线
EP3859881A1 (fr) * 2020-01-29 2021-08-04 Nokia Shanghai Bell Co., Ltd. Composant d'antenne
US11588218B1 (en) * 2021-08-11 2023-02-21 Raytheon Company Transversely tapered frequency selective limiter

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3138643A1 (fr) * 2015-08-20 2017-03-08 The Boeing Company Systèmes et procédés de fabrication d'additif destinés à des matériaux magnétiques
US10737424B2 (en) 2015-08-20 2020-08-11 The Boeing Company Additive manufacturing methods for magnetic materials
CN108155888A (zh) * 2018-01-05 2018-06-12 北京航天微电科技有限公司 一种用于抑制电源电磁干扰的ltcc大功率emi滤波器
WO2019171769A1 (fr) * 2018-03-06 2019-09-12 国立大学法人大阪大学 Filtre passe-bande
JP2021515505A (ja) * 2018-06-26 2021-06-17 レイセオン カンパニー 二平面テーパ化線路周波数選択性リミッタ
EP3771027A1 (fr) * 2019-07-24 2021-01-27 Rockwell Collins, Inc. Limiteur sélectif à fréquence réglable
CN116886062A (zh) * 2023-07-26 2023-10-13 北京星英联微波科技有限责任公司 高阻表面波导限幅器
CN116886062B (zh) * 2023-07-26 2024-01-23 北京星英联微波科技有限责任公司 高阻表面波导限幅器

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CN108475835A (zh) 2018-08-31
KR20180103121A (ko) 2018-09-18
AU2017206716A1 (en) 2018-07-19
EP3403293B1 (fr) 2020-04-08
EP3403293A1 (fr) 2018-11-21
AU2017206716B2 (en) 2019-08-15
KR102132548B1 (ko) 2020-08-05
JP2019502324A (ja) 2019-01-24
JP6625226B2 (ja) 2019-12-25

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