High-frequency bandpass filter for an MR device comprising a coil body with a cavity, MR device

Abstract

High-frequency bandpass filter for an MR device, in particular for a transmitting and / or receiving arrangement of an MR device, comprising a resonator arrangement having a signal input, a signal output and at least one resonator, wherein each resonator has one capacitor which is connected in parallel with one inductance, characterized in that the inductance comprises an electrically conductive coil body having a cavity which is substantially high-frequency-tight. A high-frequency bandpass filter having a high quality, a high electrical load capacity and at the same time a low impedance level is thereby achieved which can be produced simply and cost-effectively.

Description

Technical Field

[0001] The present invention relates to a high-frequency bandpass filter for MR devices, and more particularly for a transmitting and / or receiving arrangement of said MR devices, the high-frequency bandpass filter comprising a resonator arrangement having a signal input terminal, a signal output terminal and at least one resonator, wherein each resonator has a capacitor connected in parallel with an inductor. Background Technology

[0002] For MR devices, such as the transmitting and receiving devices of NMR spectrometers, bandpass filters with a frequency band in the two- to three-digit MHz range are required. Conventional bandpass filters for this purpose are typically fabricated on a single circuit board in a cast or milled housing using wound cylindrical coils and / or milled helical resonators. [1] One such bandpass filter design is disclosed. Frequency compensation based on tolerances is performed by a trimmer capacitor. Active and passive units are typically interconnected using coaxial cables and coaxial plug connectors. However, such bandpass filters require high labor costs in constructing the filter and in subsequent compensation. In addition, multiple coils or helical resonators and trimmer capacitors must be stocked, which increases manufacturing costs. Furthermore, the entire construction is susceptible to mechanical shock and vibration and has a certain temperature dependence.

[0003] [7] A dielectric resonator type bandpass filter with symmetrical attenuation point characteristics is disclosed. The bandpass filter is equipped with an input device that feeds a microwave input signal into a cavity 41. The bandpass filter has dielectric resonators 20 and 21, which form a bandpass filter for the input signal.

[0004] [8] A loop-gap-resonator is disclosed. The resonator includes a microwave resonant structure with a field distribution between “lumped” and “distributed” and is intended to provide an alternative for dielectric and surface acoustic wave resonators at low microwave frequencies.

[0005] [9] A split-ring resonator for magnetic resonance in the 200-2000MHz range is disclosed. Summary of the Invention

[0006] The objective of this invention is to provide a compact high-frequency bandpass filter that has high quality, high electrical load capacity, and low impedance level, and can be manufactured simply and cost-effectively.

[0007] Description of the present invention

[0008] This task is solved according to the present invention by the high-frequency bandpass filter according to claim 1 and the MR device according to claim 11.

[0009] According to the invention, the inductor comprises a conductive coil body having a cavity, the cavity being substantially sealed at high frequencies. "Substantially sealed at high frequencies" means that the magnetic field propagates within the coil body and stray fields outside the coil body are minimized. This high-frequency sealing is achieved through the selection of the shape and material of the coil body. Therefore, the magnetic flux in the resonator according to the invention is substantially completely (>99%, preferably >99.9%) contained within the coil body, thereby minimizing stray fields outside the coil body.

[0010] Resonators, including those with cavity inductors, have been used as tunable oscillating circuits for various applications [2], [3], [4], [5], [6]. High-frequency sealing is not required here and therefore not given.

[0011] In this invention, the resonator is not used as a tunable oscillating circuit, but rather as a high-frequency filter preferably having a constant resonant frequency. The resonator possesses high quality and thus high resistance at the resonant frequency due to the shape of its enclosing cavity. The shape of the coil body according to the invention and the associated large volume (outside the resonant frequency) result in not only low resistance but also low thermal resistance. This, in particular, combined with the high voltage withstand capability of the capacitor, enables high load capacity.

[0012] The geometry according to the invention ensures a small inductance in the coil body and thus, together with a large capacitor, a low impedance level.

[0013] A portion of the bandpass filter according to the invention can be manufactured in a simple manner as a machine-equippable planar circuit board. The planar circuit board may contain additional active electronic components (e.g., switches, amplifiers, etc.) for MR devices, which simplifies construction and enables cost-effective manufacturing.

[0014] The resonator's capacitance may include one or more capacitors and form an electrical oscillation circuit with the coil body. The coil body is preferably metallic, particularly made of aluminum, and in a preferred embodiment has a conductive outer wall and a central conductive support element that forms, for example, a quasi-annular cavity. The coil body may exist, for example, as a milled or cast housing or a combination thereof.

[0015] The high-frequency bandpass filter according to the invention is particularly advantageous for use, for example, in MR transmitting and receiving devices in NMR sample heads.

[0016] Preferably, the cavity of the coil body is rotationally symmetric, comprising an annular surface, i.e., a surface of rotation, with a central hole (the axis of rotation extends through the hole and does not intersect the surface of rotation). The cross-section of the rotating body parallel to the axis of rotation can be arbitrarily shaped and is preferably rectangular, including an edge rounded at least on one side. This creates a partially hollow cylindrical cavity. Here, the axis of the hollow cylinder forms the resonator axis. Therefore, a cylinder that also includes at least partially rounded edges also falls under the category of "partially hollow cylinders." In this case, the cavity cross-section tapers parallel to the resonator axis, or in other words, the cavity cross-section perpendicular to the resonator axis has different sizes at different locations along the resonator axis.

[0017] According to the invention, the resonator has a covering element that, together with the coil body, defines the cavity. The covering element is a substantially high-frequency sealed planar element that fits onto the opening of the coil body. The covering element can be fastened to the coil body, for example, by screwing, pressing, clamping, or brazing.

[0018] Preferably, the covering element is configured as a circuit board. Alternatively, another metal component (or a metallized component) may be used as the covering element.

[0019] The covering element is preferably electrically insulating and is mostly provided with, and in particular covered with, a conductive material on the side facing the cavity.

[0020] Preferably, the side (bottom) facing the cavity is completely covered with a conductive material, except in areas where capacitors are to be installed if necessary. When the capacitor is mounted on the covering element, the covering element cannot be continuously covered, as this would short-circuit the capacitor.

[0021] When the capacitor is disposed in a support element (see below), it may be disposed, for example, on the underside of a continuous overlay of a cover element.

[0022] In a particularly preferred embodiment, the covering element has at least one through-hole contact that connects one of the contact surfaces of the capacitor and the coil body to a signal input or signal output terminal.

[0023] The through-hole contact portion connects directly to the support element contact portion, either through a conductive layer on the side of the covering element facing the cavity. If the capacitor comprises multiple capacitors, the through-hole contact portion connects a corresponding contact surface of each capacitor to the coil element.

[0024] In a particularly preferred embodiment, the covering element is a circuit board.

[0025] Preferably, an electrical input wire is provided for signal input coupling to the signal input terminal, and an electrical output wire is provided for signal output coupling from the signal output terminal, wherein the electrical input wire and the electrical output wire are preferably disposed on the outside of the covering element.

[0026] The signal input and output terminals can be located at a common contact point. The signal is then output coupled (single-port) at the same port coupled to its input (the contact point between the resonator and the input or output wire). If the resonator is connected as a single-port contact, it can be used as a series or parallel resonant circuit.

[0027] Alternatively, the signal input and signal output terminals can be positioned at different contact locations. That is, the signal is output coupled at a port different from its input coupling. If the resonator is connected by contacts as a two-port circuit, it is better suited as a bandpass filter.

[0028] According to the present invention, the capacitor is disposed within the cavity. This reduces electromagnetic losses.

[0029] In this embodiment, the side of the covering element facing the cavity is preferably electrically coated such that the layer has two electrically separated partial layers, wherein one partial layer is electrically connected to the first contact surface of the capacitor and the other partial layer is electrically connected to the second contact surface of the capacitor.

[0030] Alternatively or additionally, the capacitor may also be disposed outside the cavity. This has the advantage of compensating the resonator when the capacitor is in the installed state. The covering element is preferably coated with a conductive material not only on the side (lower side) facing the cavity but also on the side (upper side) facing away from the cavity. The degree of coating depends on the amount and arrangement of the capacitor outside the cavity.

[0031] According to the invention, a conductive intermediate layer is provided between the side of the covering element facing away from the cavity and the side facing the cavity. The intermediate layer connects the radially outer contact surfaces of the different capacitors in the arrangement in a low-impedance manner. The intermediate layer serves to electromagnetically seal the cavity, especially when the capacitor has a capacitor within the cavity, because in this case, the side facing the cavity cannot be fully conductively covered. This minimizes stray fields outside the cavity and thus optimizes high-frequency sealing.

[0032] The current connection is preferably made through a blind hole contact to the side of the cover element facing the cavity and through a through hole contact to the cover element. A through hole contact may also be used instead of a blind hole contact.

[0033] The capacitors may comprise multiple capacitors connected in parallel. Preferably, the capacitors are arranged symmetrically, and especially rotationally symmetrically, around the resonator axis. The capacitor arrangement is preferably chosen such that the area utilized by the capacitors is as small as possible. This effectively suppresses other (interfering) resonances. A circular annular structure is particularly preferred, in which the capacitors are arranged as close to each other as possible. This reduces the capacitance between the support element and, if necessary, the conductive intermediate layer.

[0034] In addition, it is also possible that the capacitor is also located outside the cavity, either entirely or partially.

[0035] In one particular embodiment, the capacitor is formed from an insulating sheet, particularly a ceramic sheet, coated with a conductive material. This layer forms the contact surface of the capacitor.

[0036] Preferably, in this embodiment, an insulating sheet is disposed between the support element and the cover element. The insulating sheet is then electrically coated on its two opposing sides and mechanically connects the cover element to the coil body. This achieves a particularly compact implementation of the capacitor. The first contact surface is preferably electrically connected to the underside of the cover element.

[0037] The insulating sheet is preferably configured as a ring with a central through-hole contact portion.

[0038] To improve filtering performance, a particularly preferred embodiment of the high-frequency bandpass filter according to the present invention specifies that the resonator arrangement includes at least two mutually coupled resonators. In the coupled resonators, the input and output wires are preferably connected to the ports of different resonators.

[0039] Preferably, the resonators are coupled by their magnetic fields, wherein the cavities of two corresponding resonators of the at least two resonators are interconnected through openings in the coil body.

[0040] Alternatively, coupling via passive components (coils, capacitors, wires) is also possible.

[0041] The center frequency of the high-frequency bandpass filter according to the invention is preferably in the range of two to three digits in MHz. This can be achieved, for example, by the following characteristic data for the resonator: cavity diameter: 32mm-90mm, cavity height: 7mm-22mm, and the inductance of the coil body thus given: 1.5nH-7.0nH.

[0042] The power tolerance of the resonator is limited by the power tolerance of the capacitor and the insulation of the covering element. The high-frequency bandpass filter according to the invention is suitable for power greater than 500W and can therefore be advantageously used in HR (High Resolution) and MAS (Magic Angle Spinning) MR applications.

[0043] The present invention also relates to an MR device having a transmitting and / or receiving arrangement having the previously described high-frequency bandpass filter.

[0044] Furthermore, a resonator comprising a signal input terminal, a signal output terminal, and an inductor can be used as a high-frequency bandpass filter for MR applications, particularly in the transmitting and / or receiving arrangements of MR devices, wherein the inductor comprises a conductive coil body with a cavity. The resonator here preferably has a constant resonant frequency and is substantially hermetically sealed at high frequencies.

[0045] Other advantages of the invention become apparent from the specification and drawings. Similarly, the features described above and further explained can be used individually or in any combination according to the invention. The illustrated and described embodiments should not be construed as a closed enumeration, but rather as exemplary features used to describe the invention. Attached Figure Description

[0046] Detailed description and accompanying drawings of the present invention

[0047] Figure 1 A cross-section of a resonator of a high-frequency bandpass filter according to the invention, including a capacitor disposed within a cavity, is shown.

[0048] Figure 2 Show Figure 1 The projection of the components of the resonator.

[0049] Figure 3 Showing includes Figure 1 The resonator and single-port terminals are shown in the cross-section of the resonator arrangement structure, which schematically illustrates the signal flow.

[0050] Figure 4 Show Figure 3 The projection of the components of the resonator arrangement structure in the image.

[0051] Figure 5 Show Figure 3 The equivalent circuit diagram of the resonator arrangement structure in the image.

[0052] Figure 6 Showing includes Figure 1 The resonator and two-port terminals are shown in the cross-section of the resonator arrangement structure, which schematically illustrates the signal flow.

[0053] Figure 7 Show Figure 6 The projection of the components of the resonator arrangement structure in the image.

[0054] Figure 8 Show Figure 6 The equivalent circuit diagram of the resonator arrangement structure in the image.

[0055] Figure 9 A cross-section of a resonator of a high-frequency bandpass filter according to the invention, including capacitors disposed inside and outside the cavity, is shown.

[0056] Figure 10 A cross-section of a resonator of a high-frequency bandpass filter according to the invention, including a capacitor, is shown, the capacitor being configured in the form of a central insulating sheet.

[0057] Figure 11 Show Figure 10 The signal flow is schematically shown in the resonator.

[0058] Figure 12 A perspective cross-sectional view of a coil element in a particularly preferred embodiment of the high-frequency bandpass filter according to the invention, including a coupled resonator, is shown.

[0059] Figure 13 The projection shows a component of a resonator arrangement structure including coupled resonators.

[0060] Figure 14 An equivalent circuit diagram of a resonator arrangement including coupled resonators is shown. Detailed Implementation

[0061] Figure 1 and Figure 2 A cross-section or projection of a resonator 10 in a first embodiment of a high-frequency bandpass filter 12 according to the present invention is shown. The resonator 10 includes an inductor configured as a coil body 11 including a cavity 9 and forming an oscillating circuit with a capacitor 1. The resonator 10 has a capacitor formed by the capacitor 1 disposed within the cavity 9.

[0062] The coil body 11 shown in the embodiment is rotationally symmetric, wherein the cavity 9 of the coil body 11 is substantially hollow cylindrical and includes a portion of the rounded edge in the region below the coil body 11, i.e., on the side of the coil body 11 opposite to the covering element 7. The coil body 11 has a large conductive surface and therefore low resistance.

[0063] The coil body 11 includes a central conductive support element 2 (in Figure 1In the cross-section, the radially inner part of the U-shaped wall, i.e., the near-axial portion), the outer wall 13 (in Figure 1 The portion shown is below the U-shaped wall in cross-section and radially outward, i.e., off-axis. The resonator 12 includes a covering element 7 that encloses the coil body 11 relative to the housing.

[0064] The support element 2 and the outer wall 13 are made of conductive material. The support element 2 is preferably hollow and has a central through-hole 8. The covering element 7 is preferably an insulator with a conductive coating, especially a circuit board, on the underside (side facing the cavity 9) of which is provided, especially coated with, a conductive layer 5 (in... Figure 2 (Horizontal dashed line in the diagram). Between the two contact surfaces 1a and 1b of capacitor 1, the underside of the covering element 7 does not have a conductive layer. Therefore, the conductive layer 5 is... Figure 1 and Figure 2 The embodiment shown has partial layers 5a and 5b, which are electrically separated from each other. The first partial layer 5a is currently connected to a corresponding first contact surface 1a of the capacitor 1 and is electrically at a reference potential (e.g., ground potential). The second partial layer 5b is currently connected to a corresponding second contact surface 1b of the capacitor 1. The arrangement of the capacitor 1 is generally chosen such that the area unfolded by the capacitor is as small as possible to effectively suppress interfering resonances.

[0065] To ensure the best possible electromagnetic sealing of the cavity 9 despite the presence of the uncoated surface 15, a conductive intermediate layer 6 can be provided between the upper and lower sides of the covering element 7 (i.e., within the covering element 7). Figure 2 (The vertical dashed line in the image), the intermediate layer connects the radially outer contact surfaces 1a of capacitor 1 to each other in a low-impedance manner. Figure 1 and Figure 2 In the embodiment shown, the current connection is made through the first partial layer 5a and the blind hole contact portion 3 that opens toward the cavity 9. Except for the opening in the through hole contact portion 4, the cavity 9 is electromagnetically closed.

[0066] As in Figure 2 As shown, in this embodiment, the capacitors 1 are uniformly distributed around the resonator axis 14 in a circular annular structure (i.e., spaced equidistant from the resonator axis 14). This allows the capacitors 1 to be positioned as close to each other as possible, thereby reducing the capacitance between the support element 2 and the conductive intermediate layer 6. The conductive layers 5a and 5b are correspondingly annular and concentric, and separated from the annular surface 15 surrounding the cladding. Alternatively, a single annular capacitor (with two annular contact surfaces) may also be provided.

[0067] The high-frequency bandpass filter 12 according to the present invention can be connected to components of an MR device via ports P, P1, and P2. For this purpose, said ports include signal input terminals for coupling the input of the signal to be filtered and / or signal output terminals for coupling the output of the filtered signal. For example, in... Figure 3 and Figure 4 As shown, resonator 1 can be wired as a single-port circuit (signal input and signal output are implemented in a single port P). The corresponding equivalent circuit diagram is shown in [the diagram]. Figure 5 As shown in the image. Figure 6 and Figure 7 This illustrates an alternative wiring (two-port) route through two separate ports P1 and P2. The corresponding equivalent circuit diagram is shown in... Figure 8 As shown in the diagram. Two connection possibilities (single-port and dual-port) can be implemented with all embodiments 12, 12', 12'' described herein, and an example of the first embodiment 12 is shown in the diagram. Figures 3 to 7 As shown in the diagram. In a first embodiment of the high-frequency bandpass filter 12, ports P, P1, and P2 are currently connected to the second partial layer 5b via through-hole contacts 4. The through-hole contacts 4 are therefore in energized contact with the upper and lower sides of the cover element 7, but not currently connected to the intermediate layer 6. Input wires 17 and output wires 18 are guided from ports P or P1, P2 of the high-frequency bandpass filter 12 to the component to be connected (not shown). Input wires 17 and output wires 18 are preferably configured as conductor circuits on the side of the cover element 7 facing away from the cavity.

[0068] exist Figure 3 and Figure 6 The diagram illustrates the signal flow for a single-port or dual-port variant of the high-frequency bandpass filter 12. The high-frequency signal to be filtered is coupled through a conductive component (input wire 17) on the surface of the cover element and passes through the through-hole contact 4. The high-frequency signal is separated at the lower end of the through-hole contact 4. The high-frequency component of the high-frequency signal to be filtered, coupled through the input wire 17, is guided from the signal input port P or P1 through the second layer 5b of the cover element 7, the capacitor 1, and the first layer 5a of the cover element 7 to a reference potential (e.g., ground potential). The low-frequency component of the high-frequency signal to be filtered is guided from the signal input port P or P1 through the second layer 5b of the cover element 7, the support element 2 along the inner wall of the cavity 9, and the outer wall 13 of the coil body 11 to the lower side of the cover element 7 to a reference potential (e.g., ground potential). For frequencies close to the resonant frequency of the resonator, the resonator is high-impedance. The corresponding component of the high-frequency signal to be filtered oscillates in the resonator and can be coupled from the output of the high-frequency bandpass filter 12 through the signal output port P or P2. Because the frequency of the high-frequency signal to be filtered is in the MHz range, signal transmission occurs only through the conductive surface of resonator 2.

[0069] Figure 9 A cross-section of a resonator 10' of a high-frequency bandpass filter 12' according to the invention is shown, including a coil body 11' with a capacitor, the capacitor being formed by a capacitor 1 disposed within a cavity 9 and a capacitor 1' disposed outside the cavity 9.

[0070] Here, the first contact surfaces 1a and 1a' of capacitors 1 and 1' located inside and outside the cavity 9 are electrically connected to each other through-hole contact portions 3'. Similarly, the second contact surfaces 1b and 1b' of capacitors 1 and 1' located inside and outside the cavity 9 are electrically connected to each other. Conversely, unlike the through-hole contact portion 4, the other through-hole contact portions 3' are electrically connected not only to the upper and lower sides of the covering element 7, but also to the intermediate layer 6. The other through-hole contact portions 3' therefore also satisfy... Figure 1 The function of the blind hole contact 3 in the cavity 9 is as follows: The input wire 17 is electrically connected to the second contact surface 1b of capacitors 1 and 1' and, if necessary, must be guided around the first contact surface 1b' of capacitor 1' located outside the cavity 9. Alternatively, the input wire 17 can also be guided to the contact surface 1b' through another intermediate layer (not shown).

[0071] Figure 10 A cross-section of a resonator 10'' with a high-frequency bandpass filter 12'' according to the invention, having a capacitor 1'', is shown. The capacitor is formed in the form of a central insulating sheet (e.g., an insulating diaphragm or ceramic sheet) with conductive coatings on both sides (capacitor 1''). The layers of the insulating sheet form the contact surfaces 1a'' and 1b''' of the capacitor 1''. In this embodiment, the lower side 5 of the covering element 7 can be completely covered. A through-hole contact portion 4'' is centrally located in this embodiment and contacts one of the two contact surfaces 1a'' and 1b'' of the capacitor 1'' (exemplarily the lower contact surface 1b''). In contrast to the previously described embodiments, the through-hole contact portion 4'' contacts the support element 2 directly and not through a portion of the lower side of the covering element 7. The support element 2 is preferably solid in this embodiment.

[0072] Figure 11The diagram illustrates a corresponding signal flow exemplarily used in a single-port variant. The high-frequency component of the high-frequency signal to be filtered, coupled via input wire 17, is guided from port P through via through-hole contact 4'', capacitor 1'', support element 2 along the inner wall of cavity 9, and outer wall 13 of coil body 11'' to the underside of cover element 7 to a reference potential (e.g., ground potential). The low-frequency component of the high-frequency signal to be filtered, coupled via input wire 17, is guided from port P through via through-hole contact 4'' and layer 5 on the underside of cover element 7 to the reference potential (e.g., ground potential). The unfiltered component of the high-frequency signal to be filtered is thus coupled from the output of high-frequency bandpass filter 12'' via port P.

[0073] Resonators 10, 10', and 10'' can each function individually as high-frequency bandpass filters 12, 12', and 12'' according to the present invention (simple resonator arrangement structure) or be coupled with other resonators 10, 10', and 10'' to form a more complex resonator arrangement structure 20 in order to improve the filtering effect.

[0074] Figure 12 A perspective cross-sectional view of a coil body 11 is shown in a particularly preferred embodiment of a high-frequency bandpass filter 12''' according to the invention, having such a resonator arrangement 20, wherein the resonator arrangement has coupled resonators 10. The coil body 11''' comprises a plurality of partial coil bodies 11a, 11b, 11c, which are electrically and mechanically connected to each other through openings 21, allowing magnetic fields to couple with each other, thereby achieving particularly good performance. The coil body 11''', comprising the three partial coil bodies 11a, 11b, 11c, is preferably machined as a single piece (e.g., as a single milled part) and preferably enclosed by a single covering element (not shown), which comprises three partial covering elements having components of the covering element of a single resonator, as previously described.

[0075] Figure 13 The diagram shows a projection of the components of a resonator arrangement 20 with coupled resonators 10. The two external resonators are each connected as single-port contacts. The entire resonator arrangement 20 is therefore again wired as a two-port arrangement. The equivalent circuit diagram of the resonator arrangement 20 is shown in... Figure 14 As shown in the image.

[0076] List of reference numerals

[0077] 1. Capacitor inside the cavity

[0078] 1. Capacitor outside the cavity

[0079] 1. Capacitors in the support element

[0080] The first contact surfaces of capacitors 1a, 1a', and 1a''

[0081] The second contact surfaces of capacitors 1b, 1b', and 1b''

[0082] 2. Conductive support element

[0083] 3 blind hole contact part

[0084] 4-hole contact section

[0085] 4`` Central through-hole contact part

[0086] 5 conductive layers

[0087] 5a First Part Layer

[0088] 5b Part 2 Layer

[0089] 6 conductive intermediate layers

[0090] 7. Covering components (PCB)

[0091] 8 through holes

[0092] 9 cavity

[0093] 10 Resonators with capacitors in the cavity

[0094] (Simple resonator arrangement structure)

[0095] 10. Resonator with capacitances inside and outside the cavity.

[0096] (Simple resonator arrangement structure)

[0097] 10`` Resonator with capacitance in the support element

[0098] (Simple resonator arrangement structure)

[0099] 11, 11`, 11``, 11``` coil body

[0100] Coil bodies 11a, 11b, and 11c

[0101] 12, 12`, 12``, 12`` High-frequency bandpass filters

[0102] 13 outer wall

[0103] 14 resonator axes

[0104] 15 Uncoated surfaces

[0105] 17 Electrical input wires

[0106] 18 electrical output wires

[0107] 20 Resonator Arrangement Structure with Multiple Coupled Resonators

[0108] 21. Opening in the coil body

[0109] P has a port with signal input and signal output terminals.

[0110] P1 has a port with a signal input terminal.

[0111] P2 has a port with a signal output terminal.

[0112] Reference List

[0113] [1] “Helical resonator bandpass filter”

[0114] https: / / coil32.net / design / helix-resonator.html

[0115] [2] Garbacz et al.

[0116] “A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER)”

[0117] The Journal of Chemical Physics145, 104201 (2016)

[0118] DOI: 10.1063 / 1.4962285

[0119] https: / / aip.scitation.org / doi / abs / 10.1063 / 1.4962285

[0120] [3] Bobowski et al.

[0121] “Permittivity and Conductivity Measured using a Novel Toroidal Split-Ring Resonator”

[0122] https: / / arxiv.org / pdf / 1901.00994.pdf

[0123] [4] Crypto Museum

[0124] “Pulsed Cavity Resonant cavity microphone”

[0125] https: / / www.cryptomuseum.com / covert / bugs / ec / cavity / index.htm

[0126] [5]Su et al

[0127] “Slot Antenna Integrated Re-Entrant Resonator Based Wireless PressureSensor for High-Temperature Applications”

[0128] Sensors 2017, 17, 1963;

[0129] DOI:10.3390 / s17091963

[0130] https: / / www.mdpi.com / 1424-8220 / 17 / 9 / 1963 / htm

[0131] [6] Anand et al.

[0132] “Air Cavities Integrated with Surface Mount Tuning Components forTunable Evanescent-Mode Resonators”

[0133] https: / / www.researchgate.net / publication / 306117073

[0134] DOI:10.1109 / MWSYM.2016.7539960

[0135] [7] JP2001127502A

[0136] [8] MEHDIZADEH M ET AL:

[0137] "Loop-Gap Resonator: A Lumped Mode Microwave Resonant Structure",

[0138] IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, IEEE, USA

[0139] Vol. 30, No. 12, December 1, 1983 (1983-12-01), pages 1059-1064,

[0140] [9] HARDY W ET AL: "Split-ring resonator for use in magneticresonance from 200-2000 MHz",

[0141] REVIEW OF SCIENTIFIC INSTRUMENTS,

[0142] Vol. 52, No. 2, February 1, 1981 (1981-02-01), pages 213-216.

Claims

1. MR device comprising a transmitting and / or receiving arrangement, the transmitting and / or receiving arrangement having a high-frequency bandpass filter (12, 12', 12", 12'"), the high-frequency bandpass filter comprising a resonator arrangement (10, 10', 10", 20) having a signal input, a signal output and at least one resonator (10, 10', 10"), wherein, Each resonator (10, 10', 10'') has a capacitor connected in parallel with an inductor. The inductor includes a conductive coil body (11, 11', 11'', 11''') with a cavity (9), the cavity being essentially sealed at high frequency. The resonators (10, 10', 10'') have a covering element (7) that, together with the coil bodies (11, 11', 11'', 11''''), defines the cavity (9). The capacitor is disposed inside the cavity (9). Its features are, A conductive intermediate layer (6) is provided between the side of the covering element (7) facing away from the cavity (9) and the side facing the cavity (9).

2. The MR device as set forth in claim 1, characterized by The cavity (9) of the coil body (11, 11````) is rotationally symmetrical, especially locally cylindrical.

3. MR device according to one of the preceding claims, characterized in that The covering element (7) is electrically insulating and is at least partially provided, in particular covered, with a conductive material on the side facing the cavity (9).

4. MR device according to one of the preceding claims, characterized in that The covering element (7) has at least one through-hole contact portion (4), which connects one of the contact surfaces (1a, 1b) of the capacitor and the coil body (11, 11', 11'', 11''') to the signal input terminal or signal output terminal.

5. The MR device of one of the preceding claims, wherein The covering element (7) is a circuit board.

6. The MR device of one of the preceding claims, wherein The capacitor comprises multiple capacitors connected in parallel.

7. The MR device as claimed in one of claims 1 to 5, characterized in that The capacitor is formed from an insulating sheet (1``) coated with a conductive material, particularly a ceramic sheet.

8. MR device according to one of the preceding claims, characterized in that The resonator arrangement includes at least two mutually coupled resonators (10).

9. The MR device as claimed in claim 8, characterized in that The resonators (10) are coupled by their magnetic fields, wherein the cavities (9) of two corresponding resonators in the at least two resonators (10) are interconnected by an opening (21) in the coil body (2).

10. The MR device according to any one of the preceding claims, characterized in that, The center frequency of the high-frequency bandpass filter is in the range of two to three digits in MHz.

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