High-frequency bandpass filter for MR apparatus with coil body having cavity, MR apparatus

Abstract

The present invention relates to a high-frequency bandpass filter for an MR device, particularly for a transmitting and / or receiving configuration of an MR device, comprising a resonator configuration having a signal input, a signal output, and at least one resonator, wherein each resonator has a capacitor connected in parallel with an inductor, and the inductor comprises a conductive coil body having a substantially HF hermetically sealed cavity. As a result, a high-quality, high-electrical-load-tolerance, and simultaneously low-impedance HF bandpass filter is achieved that can be manufactured simply and at low cost.

Description

Technical Field

[0001] The present invention relates to a high-frequency band-pass filter for an MR device, particularly for a transmission and / or reception configuration of an MR device, comprising a resonator configuration having a signal input, a signal output, and at least one resonator, each resonator having a capacitor connected in parallel to an inductor.

Background Art

[0002] For the transmission and reception devices of an MR device, for example in the case of an NMR spectrometer, a band-pass filter having a frequency band in the range of 2 to 3 digits of MHz is required. Conventional band-pass filters for this task are usually manufactured on a single printed circuit board in which a wound cylindrical coil and / or a milled helical resonator are housed in a cast or milled housing. Non-Patent Document 1 discloses such a band-pass filter design. The frequency adjustment required due to tolerances is achieved by trimming the capacitor. The active unit and the passive unit are usually interconnected by coaxial cables and coaxial connectors. However, such a band-pass filter requires a great deal of manual labor during the construction and subsequent adjustment of the filter. Furthermore, various coils or helical resonators, and trimming capacitors have to be stocked, which increases the manufacturing cost. Also, the entire structure is susceptible to mechanical shock and vibration, and exhibits a certain temperature dependence. Patent Document 1 discloses a dielectric resonator type bandpass filter having symmetrical attenuation point characteristics. This bandpass filter includes an input means for supplying a microwave input signal to a cavity 41, which has dielectric resonators 20, 21 that form a bandpass filter for an input signal. Non-patent document 7 discloses a loop-gap resonator. This resonator comprises a microwave resonant structure having a magnetic field shape that lies between "concentration" and "dispersion" and is intended to represent an alternative to dielectric and surface acoustic wave resonators at low microwave frequencies. Non-patent document 8 discloses a split-ring resonator for magnetic resonance in the 200-2000 MHz range.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004] [Non-Patent Document 1] "Helical resonator bandpass filter" https: / / coil32.net / design / helix-resonator.html [Non-Patent Document 2] "A loop-gap resonator for chirality-sensitive nuclear magneto-electric resonance (NMER)" Garbacz et al., The Journal of Chemical Physics 145, 104201 (2016) DOI:10.1063 / 1.4962285 https: / / aip.scitation.org / doi / abs / 10.1063 / 1.4962285 [Non-Patent Document 3] “Permittivity and Conductivity Measured using a Novel Toroidal Split-Ring Resonator” Bobowski et al., https: / / arxiv.org / pdf / 1901.00994.pdf [Non-Patent Document 4] “Pulsed Cavity Resonant cavity microphone” Crypto Museum, https: / / www.cryptomuseum.com / covert / bugs / ec / cavity / index.htm [Non-Patent Document 5] “Slot Antenna Integrated Re-Entrant Resonator Based Wireless Pressure Sensor for High-Temperature Applications” Su et al., Sensors 2017, 17, 1963; DOI:10.3390 / s17091963 https: / / www.mdpi.com / 1424-8220 / 17 / 9 / 1963 / htm [Non-Patent Document 6] “Air Cavities Integrated with Surface Mount Tuning Components for Tunable Evanescent-Mode Resonators” Anand et al., https: / / www.researchgate.net / publication / 306117073 DOI:10.1109 / MWSYM.2016.7539960 [Non-Patent Document 7] "Loop-Gap Resonator: A Lumped Mode Microwave Resonant Structure," MEHDIZADEH M et al., IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, IEEE, USA, Vol. 30, No. 12, December 1, 1983 (1983-12-01), pp. 1059-1064. [Non-Patent Document 8] "Split-ring resonator for use in magnetic resonance from 200-2000 MHz," HARDY W et al., REVIEW OF SCIENTIFIC INSTRUMENTS, Vol. 52, No. 2, February 1, 1981 (1981-02-01), pp. 213-216. [Overview of the project] [Problems that the invention aims to solve]

[0005] The objective of this invention is to propose a compact HF bandpass filter that is of high quality, has high electrical load capacity and low impedance level, and can be manufactured easily and inexpensively. [Means for solving the problem]

[0006] The purpose is to provide the high-frequency bandpass filter described in claim 1, and the claim 11 This is achieved by the MR device described above.

[0007] According to the present invention, the inductor comprises a conductive coil body having a cavity that is substantially HF hermetically sealed. "Substantially HF hermetically sealed" means that the magnetic field is spread within the coil body and the leakage magnetic field outside the coil body is minimized. HF hermetically sealed properties are achieved by the shape and material selection of the coil body. Therefore, in the resonator according to the present invention, the magnetic flux is substantially completely (more than 99%, preferably more than 99.9%) contained within the coil body, such that the leakage magnetic field outside the coil body is minimized.

[0008] Resonators with inductors containing cavities have already been used as adjustable resonant circuits in various applications, as described in Non-Patent Documents 2, 3, 4, 5, and 6. In these cases, HF airtightness is neither required nor provided.

[0009] In this invention, the resonator is used not as an adjustable resonant circuit, but preferably as an HF filter with a fixed resonant frequency. Due to the shape of the resonator surrounding the cavity, the resonator is of high quality and therefore has high electrical resistance at the resonant frequency. The shape according to this invention, and the large volume of the associated coil body, result in both low electrical resistance (outside the resonant frequency) and low thermal resistance. This results in high load capacity, especially when combined with the high voltage rating of the capacitor.

[0010] The geometric shape according to the present invention ensures a small inductance for the coil body, and therefore, in combination with a large capacitance, a low impedance level is guaranteed.

[0011] Some of the bandpass filters according to the present invention can be easily manufactured in the form of machine-mountable flat modules. The flat modules may include additional active electronics for the MR device (e.g., switches, amplifiers, etc.), which simplifies the design and makes them economical to manufacture.

[0012] The capacitor of the resonator can include one or more capacitors and forms an electrical resonance circuit with the coil body. The coil body is preferably made of metal, particularly aluminum, and in a preferred embodiment, has a conductive outer wall portion and a central conductive support portion that form, for example, a toroidal cavity. The coil body may be in the form of, for example, a milled or cast housing or a combination thereof.

[0013] The HF bandpass filter according to the present invention can be advantageously used particularly in MR transmission and reception devices, for example in an NMR probe head.

[0014] Preferably, the cavity of the coil body is rotationally symmetric and is a toroidal surface, that is, a rotational surface having a hole in the center (the rotation axis passes through the hole and does not intersect the rotational surface). The cross-section of the rotating body parallel to the rotation axis can be of any shape, and preferably is a rectangle having an edge rounded on at least one side. This results in a partially hollow cylindrical cavity. The axis of the hollow cylinder forms the axis of the resonator. Thus, "partially hollow cylindrical" includes, inter alia, a cylinder having an edge that is at least partially rounded. In this case, the cavity cross-section tapers parallel to the axis of the resonator, or the cavity cross-section perpendicular to the axis of the resonator is of different sizes at different positions along the axis of the resonator.

[0015] According to the present invention, The resonator has a cover element that defines a cavity together with the coil body. The cover element is placed at the opening of the coil body and is a substantially HF-tight flat element. The cover element can be attached to the coil body, for example, by screwing, pressing, clamping, or soldering.

[0016] Preferably, the cover element is designed as a printed circuit board. Alternatively, another metal part (or metallized part) can be used as the cover element.

[0017] The cover element is preferably electrically insulating, and a conductive material is provided widely on the side facing the cavity and is particularly coated with the conductive material.

[0018] Preferably, the side (lower side) facing the cavity is completely coated with a conductive material except for the area where the capacitor can be provided. When the capacitor is arranged in the cover element, the cover element cannot be continuously coated over the entire surface because it will short-circuit the capacitor.

[0019] The lower side of the cover element is continuously coated over the entire surface, for example, when the capacitor is arranged in the support part (see below).

[0020] In a particularly preferred embodiment, the cover element has at least one through contact that connects one of the contact surfaces of the capacitor and the coil body to a signal input or a signal output.

[0021] The through contact contacts the support part directly or via the conductive coating on the side of the cover element facing the cavity. When the capacitor includes a plurality of capacitors, the through contact connects one contact surface of each capacitor to the coil element.

[0022] In a particularly preferred embodiment, the cover element is a printed circuit board.

[0023] Preferably, an electrical input line is available for coupling a signal into the signal input, and an electrical output line is available for coupling a signal out from the signal output, and these lines are preferably arranged outside the cover element.

[0024] The signal input and signal output can be placed at a common contact point. In this case, the signal is coupled out at the same port (the contact point to the input or output line of the resonator) into which it is coupled in (1 port). When a resonator is contacted as 1 port, it can be used as a series or parallel resonant circuit.

[0025] Alternatively, the signal input and signal output can be located at different contact points. In this case, the signal is coupled out at a different port than where it is coupled in. When the resonator is contacted as two ports, it is better suited as a bandpass filter.

[0026] In this invention According to, The capacitor is placed inside the cavity. This reduces electromagnetic losses.

[0027] In this embodiment, the cavity-facing side of the cover element is preferably electrically coated such that the coating includes two partial coatings electrically isolated from each other. One partial coating is electrically connected to a first contact surface of the capacitor, and the other partial coating is electrically connected to a second contact surface of the capacitor.

[0028] Alternatively or as an addition, capacitors may also be placed outside the cavity. This has the advantage of tuning the resonator in the installed state. In this case, the cover element is preferably coated with a conductive material on both the side facing the cavity (bottom side) and the side facing the outside of the cavity (top side). The degree of coating depends on the amount and arrangement of capacitors outside the cavity.

[0029] According to the present invention,For cover elements, it is advantageous to place a conductive interlayer between the side facing the cavity and the side facing the cavity. The interlayer electrically connects the radially outer contact surfaces of the various capacitors being placed with low impedance. In this case, since the side facing the cavity cannot be completely coated conductively, the interlayer helps to electromagnetically seal the cavity, especially when the capacitance is that of the capacitors inside the cavity. This minimizes leakage of the magnetic field to the outside of the cavity and thus optimizes HF airtightness.

[0030] Electrical connections are preferably made by blind hole contacts on the cavity-facing side of the cover element and through contacts on the cover element. Through contacts can also be used instead of blind hole contacts.

[0031] The capacitance may include several capacitors connected in parallel. The capacitors are preferably arranged symmetrically, particularly rotationally, around the axis of the resonator. The arrangement of the capacitors is preferably chosen to cover the smallest possible area. This effectively suppresses other (interfering) resonances. A circular ring structure in which the capacitors are arranged as close to each other as possible is particularly preferred. This reduces the capacitance between the support and any conductive intermediate layer.

[0032] Furthermore, it is also possible to place the capacitor entirely or partially outside the cavity.

[0033] In a particular embodiment, the capacitor is formed by an insulating disk, particularly a ceramic disk, coated with a conductive material. The coating forms the contact surface of the capacitor.

[0034] In this embodiment, the insulating disk is preferably positioned between the support and the cover element. The insulating disk has two opposing surfaces that are electrically coated, and the cover element is mechanically connected to the coil body. This allows for a particularly compact design of the capacitance. The first contact surface is preferably electrically connected to the underside of the cover element.

[0035] The insulating disc is preferably designed as a ring with a through hole in the center.

[0036] To improve the filtering effect, a particularly preferred embodiment of the high-frequency bandpass filter according to the present invention specifies that the resonator configuration comprises at least two resonators coupled to one another. In the coupled resonators, the input line and output line are preferably connected to the ports of different resonators.

[0037] Preferably, the resonators are coupled via their magnetic fields, and at least two of the cavities of the resonators are connected to each other via openings in the coil body.

[0038] Alternatively, coupling via passive elements (coils, capacitors, lines) is also possible.

[0039] The center frequency of the HF bandpass filter according to the present invention is preferably in the 2-3 order of magnitude MHz band. This can be achieved, for example, by the following characteristics for the resonator: namely, when the cavity diameter is 32 mm to 90 mm and the cavity height is 7 mm to 22 mm, the resulting coil inductance can be 1.5 nH to 7.0 nH.

[0040] The power rating of the resonator is limited by the power rating of the capacitor and the insulation of the cover element. The HF bandpass filter according to the present invention is suitable for powers of 500W or more and is therefore advantageous for use in HR (high resolution) and MAS (magic angle rotation) MR applications.

[0041] The present invention also relates to an MR device having a transmit and / or receive configuration equipped with a high-frequency bandpass filter as described previously.

[0042] Furthermore, a resonator having a signal input, a signal output, and an inductor comprising a conductive coil body having a cavity. but Used as a high-frequency bandpass filter for MR applications, particularly in the transmit and / or receive configurations of MR equipment. It is possible The resonator preferably has a constant resonant frequency and is closed to be substantially HF airtight.

[0043] Further advantages of the present invention are evident in the specification and drawings. Similarly, the features described above and those detailed below may be used individually or collectively in any combination in accordance with the present invention. The illustrated and described embodiments should not be understood as an exhaustive list, but rather as illustrative for the purpose of explaining the present invention. [Brief explanation of the drawing]

[0044] [Figure 1] This is a cross-sectional view of the resonator of an HF bandpass filter according to the present invention, in which a capacitor is arranged within the cavity. [Figure 2] This is a projection view of the components of the resonator shown in Figure 1. [Figure 3] Figure 1 is a cross-sectional view of a resonator configuration having a resonator, a single port connection, and a schematicly drawn signal flow. [Figure 4] Figure 3 is a projection view of the components of the resonator configuration. [Figure 5] Figure 3 is the equivalent circuit diagram of the resonator configuration. [Figure 6] Figure 1 is a cross-sectional view of a resonator configuration having a resonator, a two-port connection, and a schematicly drawn signal flow. [Figure 7] Figure 6 is a projection view of the components of the resonator configuration. [Figure 8] Figure 6 is the equivalent circuit diagram of the resonator configuration. [Figure 9]This is a cross-sectional view of the resonator of an HF bandpass filter according to the present invention, in which capacitors are arranged inside and outside the cavity. [Figure 10] This is a cross-sectional view of the resonator of an HF bandpass filter according to the present invention, which has a capacitor designed in the form of a central insulating disk. [Figure 11] This figure shows a schematic representation of the signal flow inside the resonator shown in Figure 10. [Figure 12] This is a perspective cross-sectional view of a coil element in a particularly preferred embodiment of an HF bandpass filter having a coupled resonator according to the present invention. [Figure 13] This is a projection view of the components of a resonator configuration having coupled resonators. [Figure 14] This is an equivalent circuit diagram of a resonator configuration having coupled resonators. [Modes for carrying out the invention]

[0045] Figures 1 and 2 show a cross-section and projection of a first embodiment of the resonator 10 of the HF bandpass filter 12 according to the present invention. The resonator 10 comprises an inductor, which is in the form of a coil body 11 having a cavity 9, and together with a capacitor 1, forms an oscillation circuit. The resonator 10 has capacitance formed by the capacitor 1 located within the cavity 9.

[0046] The coil body 11 in the illustrated embodiment is rotationally symmetric, and the cavity 9 of the coil body 11 is substantially hollow cylindrical with a partially rounded edge in the lower region of the coil body 11, i.e., on the side of the coil body 11 opposite the cover element 7. The coil body 11 has a large conductive surface and therefore low electrical resistance.

[0047] The coil body 11 comprises a central conductive support portion 2 (the radially inward portion of the U-shaped wall shown in Figure 1 in cross-section, i.e., the portion closer to the axis) and an outer wall portion 13 (the lower and radially outward portion of the U-shaped wall shown in Figure 1 in cross-section, i.e., the portion further from the axis). The resonator 12 includes a cover element 7, which closes the coil body 11 to form a housing.

[0048] The support portion 2 and the outer wall portion 13 are made of a conductive material. The support portion 2 is preferably hollow and has a central through-opening 8. The cover element 7 is preferably a conductively coated insulator, in particular a printed circuit board, and its underside (the side facing the cavity 9) is coated with a specially coated conductive layer 5 (horizontal dashed line in Figure 2). The underside of the cover element 7 does not have a conductive coating between the two contact surfaces 1a and 1b of the capacitor 1. Thus, in the embodiments shown in Figures 1 and 2, the conductive layer 5 includes electrically isolated partial coatings 5a and 5b, the first partial coating 5a being electrically connected to the first contact surface 1a of the capacitor 1 and electrically at a reference potential (e.g., ground potential). The second partial coating 5b is electrically connected to the second contact surface 1b of the capacitor 1. Generally, the arrangement of the capacitor 1 is selected so that the capacitor 1 covers the smallest possible area so that interfering resonances can be effectively suppressed.

[0049] To optimally electromagnetically seal the cavity 9 despite the uncoated surface 15, a conductive intermediate layer 6 (vertical dashed line in Figure 2) can be provided between the upper and lower parts of the cover element 7 (i.e., inside the cover element 7). This layer electrically connects the radially outer contact surface 1a of the capacitor 1 with low impedance. In the embodiments shown in Figures 1 and 2, this electrical connection is made via a first partial coating 5a and blind hole contacts 3 that open toward the cavity 9. Except for the opening in the through-contact 4, the cavity 9 is electromagnetically sealed.

[0050] In this embodiment, the capacitors 1 are arranged in a circular ring structure uniformly distributed around the axis 14 of the resonator (i.e., at the same distance from the axis 14 of the resonator), as shown in Figure 2. This allows the capacitors 1 to be placed as close to each other as possible. This reduces the capacitance between the support 2 and the conductive intermediate layer 6. The partial coatings 5a and 5b of the conductive layer are correspondingly ring-shaped and concentric, separated by layered ring-shaped surfaces 15. Alternatively, a single ring capacitor (having two ring-shaped contact surfaces) can be provided.

[0051] The HF bandpass filter 12 according to the present invention may be connected to the components of an MR device via ports P, P1, and P2. For this purpose, the ports include a signal input for coupling in the signal to be filtered and / or a signal output for coupling out the filtered signal. The resonator 1 may be connected as a single port (signal input and signal output are realized in a single port P) as shown in Figures 3 and 4. A corresponding alternative circuit diagram is shown in Figure 5. Figures 6 and 7 show an alternative wiring via two separate ports P1 and P2 (two ports). A corresponding alternative circuit diagram is shown in Figure 8. Both connection options (1-port and 2-port) can be realized in all embodiments 12, 12', and 12'' described herein, as illustrated using an example of the first embodiment 12 in Figures 3 to 7. In the first embodiment of the HF band filter 12, ports P, P1, and P2 are electrically connected to the second partial coating 5b via through-contacts 4. Thus, the through-contacts 4 are electrically in contact with the upper and lower parts of the cover element 7, but not with the intermediate layer 6. Input lines 17 and output lines 18 lead from port P or ports P1, P2 of the HF bandpass filter 12 to components (not shown) to be connected. The input lines 17 and output lines 18 are preferably formed as conductor tracks on the side of the cover element 7 facing outward from the cavity.

[0052] Figures 3 and 6 show the signal flow for modified versions of the HF bandpass filter 12 with one and two ports. The HF signal to be filtered is coupled through the conductive portion on the surface of the cover element (input line 17) and passes through the cover element via the through contact 4. The HF signal branches at the lower end of the through contact 4. The high-frequency components of the HF signal to be filtered, coupled in via the input line 17, are conducted from the signal input port P or P1 to a reference potential (e.g., ground potential) via the second partial coating 5b of the cover element 7, the capacitor 1, and the first partial coating 5a of the cover element 7. The low-frequency components of the HF signal to be filtered are conducted from the signal input port P or P1 to the underside of the cover element 7 to a reference potential (e.g., ground potential) via the second partial coating 5b of the cover element 7, the support portion 2 along the inner wall of the cavity 9, and the outer wall portion 13 of the coil body 11. At frequencies close to the resonant frequency of the resonator, the resonator has high impedance. The corresponding components of the HF signal to be filtered oscillate within the resonator and can be coupled out from the HF bandpass filter 12 via the signal output port P or P2. Since the frequency of the HF signal to be filtered is in the MHz band, signal transmission occurs only through the conductive surface of the resonator 2.

[0053] Figure 9 shows a cross-sectional view of a second embodiment of the resonator 10' of the HF bandpass filter 12' according to the present invention. The coil body 11' has capacitance formed by capacitor 1 located inside the cavity 9 and capacitor 1' located outside the cavity 9.

[0054] The first contact surfaces 1a, 1a' of capacitors 1, 1', located inside and outside the cavity 9, are electrically connected to each other via additional through-hole contacts 3'. Similarly, the second contact surfaces 1b, 1b' of capacitors 1, 1', located inside and outside the cavity 9, are electrically connected to each other. In contrast to the through-hole contact 4, the additional through-hole contact 3' is electrically connected not only to the top and bottom of the cover element 7 but also to the intermediate layer 6. Thus, the additional through-hole contact 3' also functions as the blind-hole contact 3 in Figure 1. The input line 17 is electrically connected to the second contact surface 1b of capacitors 1, 1' and, if necessary, needs to be routed around the first contact surface 1b' of capacitor 1' located outside the cavity 9. Alternatively, the input line 17 can also be routed to the contact surface 1b' via an additional intermediate layer (not shown).

[0055] Figure 10 shows a cross-sectional view of a third embodiment of the resonator 10" of the HF bandpass filter 12" according to the present invention (capacitor 1"), which is a capacitor 1" designed in the form of a central insulating disk (e.g., insulating foil or ceramic disk) with both sides electrically coated. The coating of the insulating disk forms the contact surfaces 1a" and 1b" of the capacitor 1". In this embodiment, the lower side 5 of the cover element 7 may be fully coated. A through-contact 4" is centrally located in this embodiment and contacts one of the two contact surfaces 1a" and 1b" of the capacitor 1" (here, for example, the lower contact surface 1b"). In contrast to the embodiments described earlier, the through-contact 4" here contacts the support 2 directly, rather than through a partial coating on the lower side of the cover element 7. In this embodiment, the support 2 is preferably solid.

[0056] Figure 11 shows the corresponding signal flow as an example of a modified 1-port configuration. The high-frequency components of the HF signal to be filtered, coupled in via input line 17, are led from port P through through-contact 4”, capacitor 1”, support 2, along the inner wall of the cavity 9 about the outer wall 13 of the coil body 11”, to the underside of cover element 7, to a reference potential (e.g., ground potential). The low-frequency components of the HF signal to be filtered, coupled in via input line 17, are led from port P through through-contact 4”, and the coating 5 on the underside of cover element 7, to a reference potential (e.g., earth potential). The unfiltered portion of the HF signal to be filtered is coupled out through port P from the HF bandpass filter 12”.

[0057] The resonators 10, 10', and 10'' can each function individually as HF bandpass filters 12, 12', and 12'' according to the present invention (simple resonator configuration), or they can be coupled to other resonators 10, 10', and 10'' to form a more complex resonator configuration 20 to improve the filtering effect.

[0058] Figure 12 shows a perspective cross-sectional view of a coil body 11''' of a particularly preferred embodiment of the HF bandpass filter 12''' according to the present invention, which has a resonator configuration 20 with a coupled resonator 10. The coil body 11''' includes a plurality of partial coil bodies 11a, 11b, 11c that are electrically and mechanically connected to each other through an opening 21. Thus, the magnetic fields are coupled to each other, thereby enabling particularly good performance to be achieved. The coil body 11''' comprising the three partial coil bodies 11a, 11b, 11c is preferably made as a single piece (e.g., as a single milled part) and preferably closed with a single cover element (not shown) comprising three partial cover elements having components for the cover elements of the individual resonators, as described previously.

[0059] Figure 13 shows a projection view of the components of the resonator configuration 20 formed by the coupled resonator 10. The two outer resonators are each in contact as one port. Thus, the entire resonator configuration 20 is again connected as two ports. The equivalent circuit diagram of the resonator configuration 20 is shown in Figure 14. [Explanation of Symbols]

[0060] 1. Capacitor inside the cavity 1' Capacitor outside the cavity 1” Capacitor within the support section 1a, 1a', 1a'' First contact surfaces of the capacitor 1b, 1b', 1b'' Second contact surfaces of the capacitor 2. Conductive support 3. Blind Hole Contact 4 Through-contact 4" central through-contact 5. Conductive layer (coating) 5a First partial coating 5b Second partial coating 6. Conductive interlayer 7. Cover elements (PCB) 8 Through-opening 9 Cavity 10. A resonator with a capacitor inside the cavity (simple resonator configuration) A resonator with capacitors inside and outside the 10' cavity (simple resonator configuration) A resonator with a capacitor within a 10" support (simple resonator configuration) 11, 11' 11", 11"' coil 11a, 11b, 11c Partial coil body 12, 12', 12", 12"' HF bandpass filters 13 Exterior wall 14. The axis of the resonator 15 Uncoated surfaces 17 Electrical input lines 18 Electrical output lines 20 Resonator configuration with multiple coupled resonators 21 Opening inside the coil Port with P signal input and signal output Port with P1 signal input Port with P2 signal output

Claims

1. A high-frequency bandpass filter (12, 12', 12”, 12''') for an MR apparatus, particularly for the transmitting and / or receiving configuration of the MR apparatus, comprising a resonator configuration (10, 10', 10'', 20) having a signal input, a signal output, and at least one resonator (10, 10', 10''), Each resonator (10, 10', 10") has a capacitor connected in parallel with an inductor. The inductor comprises a conductive coil body (11, 11', 11'', 11'') having a substantially HF-tightly closed cavity (9). A high-frequency bandpass filter characterized by (12, 12', 12'', 12''').

2. The cavity (9) of the coil body (11, 11'') is rotationally symmetric and, in particular, partially cylindrical. The high-frequency bandpass filter (12, 12', 12”, 12'') according to claim 1, characterized in that

3. The resonator (10, 10', 10") has a cover element (7) that defines the cavity (9) together with the coil body (11, 11', 11", 11''). A high-frequency bandpass filter (12, 12', 12”, 12''') according to claim 1 or 2, characterized in that it is the same as the one described in claim 1 or 2.

4. The cover element (7) is electrically insulating, and at least partially a conductive material is provided on the side facing the cavity (9), and in particular, it is coated with a conductive material. A high-frequency bandpass filter according to claim 3, characterized in that it is a high-frequency bandpass filter.

5. The cover element (7) has at least one through-contact (4) that connects one of the contact surfaces (1a, 1b) of the capacitor and the coil body (11, 11', 11'', 11'''') to the signal input or the signal output. A high-frequency bandpass filter (12, 12', 12”, 12''') according to claim 3 or 4, characterized in that it is the same as the one described in claim 3 or 4.

6. The cover element (7) is a printed circuit board. A high-frequency bandpass filter (12, 12', 12”, 12''') according to any one of claims 3 to 5, characterized in that

7. The capacitor is located within the cavity (9). A high-frequency bandpass filter (12, 12''') according to any one of claims 1 to 6, characterized in that

8. The conductive intermediate layer (6) is positioned between the side of the cover element (7) facing the outside of the cavity (9) and the side facing the cavity (9). The high-frequency bandpass filter (12, 12''') according to claims 3 and 7, characterized in that it is a high-frequency bandpass filter according to claims 3 and 7.

9. The capacitor includes a plurality of capacitors connected in parallel. A high-frequency bandpass filter (12, 12', 12”, 12''') according to any one of claims 1 to 8, characterized in that

10. The capacitor is formed by an insulating disk (1") coated with a conductive material, particularly a ceramic disk. A high-frequency bandpass filter (12") according to any one of claims 1 to 6, characterized in that

11. The aforementioned resonator configuration comprises at least two resonators (10) coupled to one another. A high-frequency bandpass filter (12'') according to any one of claims 1 to 10, characterized in that

12. The resonators (10) are coupled via their magnetic fields, Two of the cavities (9) of the at least two resonators (10) are connected to each other via the opening (21) of the coil body (2). The high-frequency bandpass filter (12'') according to claim 11, characterized in that...

13. The center frequency of the aforementioned HF bandpass filter is in the 2- to 3-digit MHz band. A high-frequency bandpass filter (12, 12', 12”, 12''') according to any one of claims 1 to 12, characterized in that

14. An MR apparatus comprising a transmit and / or receive configuration having a high-frequency bandpass filter (12, 12', 12'', 12''') according to any one of claims 1 to 13.

15. A resonator (10, 10', 10") having a signal input, a signal output, and an inductor comprising a conductive coil body (2) having a cavity (9), to be used as a high-frequency bandpass filter (12, 12', 12”, 12'') for MR applications, particularly in the transmit and / or receive configuration of an MR device.

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