Circulator

Abstract

A circulator suitable for use in an external field, particularly of a magnetic resonance apparatus, has a planar ferrite structure. Instead of a permanent magnet, a field conducting device is provided that is designed to strengthen or weaken an external field, and/or at least one electromagnet is provided for generating an operating field. The operating field proceeds perpendicularly through the ferrite structure.

1 .- 19 . (canceled) 
   
   
       20 . A circulator for use in an external magnetic field of a magnetic resonance apparatus, comprising:
 a flat ferrite structure; and   an operating field generator located relative to said flat ferrite structure that generates an operating field proceeding perpendicularly through said ferrite structure, said operating field generator being selected from the group consisting of a field conductor device that amplifies or attenuates said external magnetic field, and at least one electromagnet.   
   
   
       21 . A circulator as claimed in  claim 20  comprising homogenization elements located at a top and bottom of said ferrite structure that homogenize and perpendicularly align said operating field in said ferrite structure. 
   
   
       22 . A circulator as claimed in  claim 20  comprising a shield housing that surrounds said ferrite structure and conducts said external magnetic field around said ferrite structure. 
   
   
       23 . A circulator as claimed in  claim 22  wherein said operating field generator is an electromagnet, and wherein said shield housing forms at least a portion of a magnetic circuit that closes field lines of a magnetic field generated by said electromagnet. 
   
   
       24 . A circulator as claimed in  claim 23  comprising a field conductor element, forming a portion of said magnetic circuit, located at a side of said ferrite structure opposite said electromagnet, or located between said electromagnet and said shield housing. 
   
   
       25 . A circulator as claimed in  claim 20  wherein said operating field generator is an electromagnet, and comprising a yolk that closes field lines of a magnetic field generated by said electromagnet. 
   
   
       26 . A circulator as claimed in  claim 20  wherein said operating field generator is a field conductor device, and wherein said field conductor device comprises at least one field conductor element located coaxially relative to said ferrite structure that amplifies or attenuates said external magnetic field in said ferrite structure, said field conductor element being at least partially conically shaped. 
   
   
       27 . A circulator as claimed in  claim 20  comprising a magnetic circuit that closes field lines of a magnetic field generated by said operating field generator within an air gap, and wherein a width of said air gap is adjustable. 
   
   
       28 . A circulator as claimed in  claim 27  comprising a magnetic field sensor that measures said external magnetic field and generates a sensor output signal corresponding thereto, and wherein said magnetic circuit is supplied with said sensor output signal and adjusts the width of said air gap dependent on said sensor output signal. 
   
   
       29 . A circulator as claimed in  claim 27  comprising a temperature sensor that senses a temperature of an environment in which said ferrite structure is located, and generates a sensor output signal corresponding thereto, said magnetic circuit being supplied with said sensor output signal and adjusting the width of said air gap dependent thereon. 
   
   
       30 . A circulator as claimed in  claim 20  comprising a displacement device that tilts said ferrite structure relative to said external magnetic field. 
   
   
       31 . A circulator as claimed in  claim 30  comprising a magnetic field sensor that measures said external magnetic field and generates a sensor output signal corresponding thereto, said sensor output signal being supplied to said displacement device and said displacement device controlling tilting of said ferrite structure dependent on said sensor output signal. 
   
   
       32 . A circulator as claimed in  claim 30  comprising a temperature sensor that senses a temperature of an environment in which said ferrite structure is located, and that generates a sensor output signal corresponding thereto, said sensor output signal being supplied to said displacement device and said displacement device controlling tilting of said ferrite structure dependent thereon. 
   
   
       33 . A circulator as claimed in  claim 20  wherein said operating field generator is an electromagnet, and wherein said electromagnet operates with a current flowing therein, and comprising a magnetic field sensor that measures said external magnetic field and generates a sensor output signal corresponding thereto, said sensor output signal being supplied to said electromagnet and said electromagnet controlling said current dependent thereon. 
   
   
       34 . A circulator as claimed in  claim 33  wherein said operating field generator is an electromagnet having a current flowing therein, and comprising a temperature sensor that senses a temperature in an environment in which said ferrite structure is located, and that generates a sensor output signal corresponding thereto, said sensor output signal being supplied to said electromagnet and said electromagnet controlling said current dependent thereon. 
   
   
       35 . A circulator as claimed in  claim 20  comprising a cooling device that cools said ferrite structure, said cooling device being selected from the group consisting of liquid cooling devices, radiant cooling devices, and heat exchangers. 
   
   
       36 . A circulator as claimed in  claim 35  wherein said operating field generator is an electromagnet, and wherein said electromagnet is located at a side of said ferrite structure, and wherein said cooling device comprises a cooling element located at a side of said ferrite structure opposite to the side of said ferrite structure at which said electromagnet is located. 
   
   
       37 . A circulator as claimed in  claim 20  wherein said operating field generator comprises two identical electromagnets respectively located on opposite sides of said ferrite structure. 
   
   
       38 . A circulator as claimed in  claim 20  wherein said operating field generator is an electromagnet, and wherein said electromagnet comprises a coil having an inductance in a range between 80 and 120 mH. 
   
   
       39 . A circulator as claimed in  claim 20  wherein said operating field generator is an electromagnet, and wherein said electromagnet comprises a core. 
   
   
       40 . A magnetic resonance antenna device for a magnetic resonance apparatus comprising:
 an antenna configured to transmit radio-frequency signals or receive magnetic resonance signals, said antenna comprising at least one antenna terminal;   an amplifier connected to said at least one antenna terminal configured to activate said antenna;   a circulator connected between said amplifier and said at least one antenna terminal that discharges power reflected by said antenna into a power dump connected to the circulator; and   said circulator comprising a flat ferrite structure, and an operating field generator located relative to said flat ferrite structure that generates an operating field proceeding perpendicularly through said ferrite structure, said operating field generator being selected from the group consisting of a field conductor device that amplifies or attenuates said external magnetic field, and at least one electromagnet.   
   
   
       41 . A magnetic resonance antenna device as claimed in  claim 40  comprising a displacement device that mechanically tilts said circulator relative to said external magnetic field. 
   
   
       42 . A magnetic resonance apparatus comprising:
 a magnetic resonance data acquisition device comprising an antenna that radiates radio-frequency signals or receives magnetic resonance signals, said antenna having at least one antenna terminal;   an amplifier connected to said at least one antenna terminal configured to activate said antenna;   a circulator connected between said amplifier and said at least one antenna terminal that discharges power reflected by said antenna into a power dump connected to the circulator; and   said circulator comprising a flat ferrite structure, and an operating field generator located relative to said flat ferrite structure that generates an operating field proceeding perpendicularly through said ferrite structure, said operating field generator being selected from the group consisting of a field conductor device that amplifies or attenuates said external magnetic field, and at least one electromagnet.