# US 2014/0191758 A1 · Transmit Antenna Selector and Magnetic Resonance Imaging System > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191758 A1 - Document ID: US20140191758A1 - Status: Published application - Kind: A1 - Application number: 14/151,566 - Filed: 2014-01-09 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: Siemens Aktiengesellschaft - Inventors: Hong Cheng; Stefan Pott; JianMin Wang; Lan Wang - Web page: https://patentgrep.com/patent/US20140191758A1 ## CPC - G01R 33/3664: {Switching for purposes other than coil coupling or decoupling, e.g. switching between a phased array mode and a quadrature mode, switching between surface coil modes of different geometrical shapes, switching from a whole body reception coil to a local reception coil or switching for automatic coil selection in moving table MR or for changing the field-of-view (G01R33/3671 takes precedence)} - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A transmit antenna selector includes a control circuit, a body coil signal output interface, a local coil signal output interface, a radio-frequency signal input interface, and a dummy load. The control circuit includes a plurality of diodes. The control circuit electrically connects, according to a control signal and via the plurality of diodes, the radio-frequency signal input interface with the body coil signal output interface, with the local coil signal output interface, or with the dummy load. ## Claims ### Claim 1 A transmit antenna selector comprising: a control circuit; a body coil signal output interface; a local coil signal output interface; a radio-frequency signal input interface; and a dummy load; wherein the control circuit comprises a plurality of diodes, and wherein the control circuit electrically connects the radio-frequency signal input interface with the body coil signal output interface, with the local coil signal output interface, or with the dummy load, according to a control signal and via the plurality of diodes. ### Claim 2 (depends on 1) The transmit antenna selector of claim 1, wherein: the plurality of diodes comprises a first diode, a second diode and a third diode; anodes of the first diode, the second diode and the third diode are connected to the radio-frequency signal input interface; a cathode of the first diode is connected to the local coil signal output interface; a cathode of the second diode is connected to the body coil signal output interface; and a cathode of the third diode is connected to the dummy load. ### Claim 3 (depends on 1) The transmit antenna selector of claim 1, wherein: the plurality of diodes comprises a first diode, a second diode and a third diode; an anode of the first diode is connected to the radio-frequency signal input interface and the local coil signal output interface; a cathode of the first diode is grounded; an anode of the second diode is connected to the radio-frequency signal input interface; a cathode of the second diode is connected to the body coil signal output interface; an anode of the third diode is connected to the radio-frequency signal input interface and the dummy load; a cathode of the third diode is grounded; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the first diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the third diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the dummy load and the anode of the third diode. ### Claim 4 (depends on 3) The transmit antenna selector of claim 3, further comprising: a first inductor between the radio-frequency signal input interface and the anode of the first diode to effect the phase difference therebetween; a second inductor between the radio-frequency signal input interface and the anode of the third diode to effect the phase difference therebetween; and a third inductor between the dummy load and the anode of the third diode to effect the phase difference therebetween. ### Claim 5 (depends on 1) The transmit antenna selector of claim 1, further comprising a body coil signal input interface, wherein, when the radio-frequency signal input interface is electrically connected with the body coil signal output interface, the control circuit electrically connects the body coil signal input interface with the dummy load in accordance with a control signal and via the plurality of diodes. ### Claim 6 (depends on 5) The transmit antenna selector of claim 5, wherein: the plurality of diodes comprises a first diode, a second diode, a third diode and a fourth diode; anodes of the first diode, the second diode and the third diode are connected to the radio-frequency signal input interface; a cathode of the first diode is connected to the local coil signal output interface; a cathode of the second diode is connected to the body coil signal output interface; a cathode of the third diode is connected to the dummy load and an anode of the fourth diode; and a cathode of the fourth diode is connected to the body coil signal input interface. ### Claim 7 (depends on 5) The transmit antenna selector of claim 5, wherein: the plurality of diodes comprises a first diode, a second diode, a third diode and a fourth diode; an anode of the first diode is connected to the radio-frequency signal input interface and the local coil signal output interface; a cathode of the first diode is grounded; an anode of the second diode is connected to the radio-frequency signal input interface; a cathode of the second diode is connected to the body coil signal output interface; an anode of the third diode is connected to the radio-frequency signal input interface, the dummy load and an anode of the fourth diode; a cathode of the third diode is grounded; a cathode of the fourth diode is connected to the body coil signal input interface; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the first diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the third diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the dummy load and the anode of the third diode; and a phase difference of an odd number of multiples of a quarter wavelength is present between the anode of the fourth diode and the anode of the third diode. ### Claim 8 (depends on 7) The transmit antenna selector of claim 7, further comprising: a first inductor between the anode of the first diode and the radio-frequency signal input interface to effect the phase difference therebetween; and a second inductor between the dummy load and the anode of the fourth diode to effect the phase difference therebetween. ### Claim 9 (depends on 1) The transmit antenna selector of claim 1, wherein the control circuit further comprises: a plurality of protection circuits, each protection circuit of the plurality of protection circuits being connected in parallel to a respective diode of the plurality of diodes; and a plurality of power supplies, each power supply of the plurality of power supplies being connected in series to a respective diode of the plurality of diodes; wherein: each protection circuit of the plurality of protection circuits comprises a capacitor and an inductor connected to the capacitor in series; and the plurality of power supplies are operative to control activation of the plurality of diodes. ### Claim 10 (depends on 2) The transmit antenna selector of claim 2, wherein the control circuit further comprises: a plurality of protection circuits, each protection circuit of the plurality of protection circuits being connected in parallel to a respective diode of the plurality of diodes; and a plurality of power supplies, each power supply of the plurality of power supplies being connected in series to a respective diode of the plurality of diodes; wherein: each protection circuit of the plurality of protection circuits comprises a capacitor and an inductor connected to the capacitor in series; and the plurality of power supplies are operative to control activation of the plurality of diodes. ### Claim 11 (depends on 3) The transmit antenna selector of claim 3, wherein the control circuit further comprises: a plurality of protection circuits, each protection circuit of the plurality of protection circuits being connected in parallel to a respective diode of the plurality of diodes; and a plurality of power supplies, each power supply of the plurality of power supplies being connected in series to a respective diode of the plurality of diodes; wherein: each protection circuit of the plurality of protection circuits comprises a capacitor and an inductor connected to the capacitor in series; and the plurality of power supplies are operative to control activation of the plurality of diodes. ### Claim 12 A magnetic resonance imaging system comprising: a transmit antenna selector comprising: a control circuit; a body coil signal output interface; a local coil signal output interface; a radio-frequency signal input interface; and a dummy load; wherein the control circuit comprises a plurality of diodes, and wherein the control circuit electrically connects the radio-frequency signal input interface with the body coil signal output interface, with the local coil signal output interface, or with the dummy load, according to a control signal and via the plurality of diodes. ### Claim 13 (depends on 12) The magnetic resonance imaging system of claim 12, wherein: the plurality of diodes comprises a first diode, a second diode and a third diode; anodes of the first diode, the second diode and the third diode are connected to the radio-frequency signal input interface; a cathode of the first diode is connected to the local coil signal output interface; a cathode of the second diode is connected to the body coil signal output interface; and a cathode of the third diode is connected to the dummy load. ### Claim 14 (depends on 12) The magnetic resonance imaging system of claim 12, wherein: the plurality of diodes comprises a first diode, a second diode and a third diode; an anode of the first diode is connected to the radio-frequency signal input interface and the local coil signal output interface; a cathode of the first diode is grounded; an anode of the second diode is connected to the radio-frequency signal input interface; a cathode of the second diode is connected to the body coil signal output interface; an anode of the third diode is connected to the radio-frequency signal input interface and the dummy load; a cathode of the third diode is grounded; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the first diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the third diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the dummy load and the anode of the third diode. ### Claim 15 (depends on 14) The magnetic resonance imaging system of claim 14, wherein the transmit antenna selector further comprises: a first inductor between the radio-frequency signal input interface and the anode of the first diode to effect the phase difference therebetween; a second inductor between the radio-frequency signal input interface and the anode of the third diode to effect the phase difference therebetween; and a third inductor between the dummy load and the anode of the third diode to effect the phase difference therebetween. ### Claim 16 (depends on 12) The magnetic resonance imaging system of claim 12, wherein the transmit antenna selector further comprises a body coil signal input interface, wherein, when the radio-frequency signal input interface is electrically connected with the body coil signal output interface, the control circuit electrically connects the body coil signal input interface with the dummy load in accordance with a control signal and via the plurality of diodes. ### Claim 17 (depends on 16) The magnetic resonance imaging system of claim 16, wherein: the plurality of diodes comprises a first diode, a second diode, a third diode and a fourth diode; anodes of the first diode, the second diode and the third diode are connected to the radio-frequency signal input interface; a cathode of the first diode is connected to the local coil signal output interface; a cathode of the second diode is connected to the body coil signal output interface; a cathode of the third diode is connected to the dummy load and an anode of the fourth diode; and a cathode of the fourth diode is connected to the body coil signal input interface. ### Claim 18 (depends on 16) The magnetic resonance imaging system of claim 16, wherein: the plurality of diodes comprises a first diode, a second diode, a third diode and a fourth diode; an anode of the first diode is connected to the radio-frequency signal input interface and the local coil signal output interface; a cathode of the first diode is grounded; an anode of the second diode is connected to the radio-frequency signal input interface; a cathode of the second diode is connected to the body coil signal output interface; an anode of the third diode is connected to the radio-frequency signal input interface, the dummy load and an anode of the fourth diode; a cathode of the third diode is grounded; a cathode of the fourth diode is connected to the body coil signal input interface; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the first diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the radio-frequency signal input interface and the anode of the third diode; a phase difference of an odd number of multiples of a quarter wavelength is present between the dummy load and the anode of the third diode; and a phase difference of an odd number of multiples of a quarter wavelength is present between the anode of the fourth diode and the anode of the third diode. ### Claim 19 (depends on 18) The magnetic resonance imaging system of claim 18, wherein the transmit antenna selector further comprises: a first inductor between the anode of the first diode and the radio-frequency signal input interface to effect the phase difference therebetween; and a second inductor between the dummy load and the anode of the fourth diode to effect the phase difference therebetween. ### Claim 20 (depends on 12) The magnetic resonance imaging system of claim 12, wherein the control circuit further comprises: a plurality of protection circuits, each protection circuit of the plurality of protection circuits being connected in parallel to a respective diode of the plurality of diodes; and a plurality of power supplies, each power supply of the plurality of power supplies being connected in series to a respective diode of the plurality of diodes; wherein: each protection circuit of the plurality of protection circuits comprises a capacitor and an inductor connected to the capacitor in series; and the plurality of power supplies are operative to control activation of the plurality of diodes.