Method for transmitting radio frequency signals to an MRI RF coil
A magnetic resonance imaging (MRI) apparatus that includes a multi-resonance transmit/receive (T/R) switch, one switch design having a top side and a bottom side of a microstripline based hybrid coupler, a first pin diode, a second pin diode, four vertical transmission lines and six horizontal transmission lines arranged in a bended manner on the microstripline. The top side is associated with a first port and a second port, and electrically connected to the first pin diode and the second pin diode. The bottom side is associated with a third port and a fourth port, and electrically connected with the first pin diode and the second pin diode. The switch receives radio frequency (RF) pulses of different frequencies transmitted to and received from an MRI RF coil where the different frequencies are received concurrently and without tuning by the multi-resonance T/R switch from the MRI RF coil.
1 . A method of transmitting radio frequency signals to an MRI RF coil from a microstripline based hybrid coupler T/R switch comprising:
forward biasing a first pin diode and a second pin diode both electrically connected to the microstripline based hybrid coupler T/R switch;
receiving an RF input signal on a first port of the microstripline-based hybrid coupler T/R switch; and
transmitting the RF input signal through a second port the of the microstripline-based hybrid coupler T/R switch to the MRI RF coil,
wherein the multi-resonance transmit/receive (T/R) switch comprises:
a microstripline based hybrid coupler having a top side and a bottom side;
the first pin diode;
the second pin diode;
four vertical transmission lines arranged in a bended manner and six horizontal transmission lines arranged in a bended manner on the microstripline based hybrid coupler;
wherein the top side of the microstripline based hybrid coupler is associated with the first port and the second port, and electrically connected to the first pin diode and the second pin diode, and wherein the bottom side is associated with a third port and a fourth port, and the bottom side is electrically connected with the first pin diode and the second pin diode; and
wherein the multi-resonance transmit/receive (T/R) switch is configured to receive RF pulses of different frequencies that are transmitted to and received from the MRI RF coil, wherein the different frequencies are received concurrently and without tuning by the multi-resonance transmit/receive (T/R) switch from the MRI RF coil.
2 . The method of claim 1 , wherein the microstripline based hybrid coupler comprises four branches.
3 . The method of claim 1 , wherein a length of at least one transmission line is between 55 cm and 105 cm.
4 . The method of claim 1 , wherein the top side and the bottom side of the multi-resonance transmit/receive (T/R) switch are rectangular in shape.
5 . The method of claim 1 , wherein the top side and the bottom side of the multi-resonance transmit/receive (T/R) switch are of equal sizes.
6 . The method of claim 1 , wherein a length of the microstripline based hybrid coupler is less than 540 mm and a width of the microstripline based hybrid coupler is less than 175 mm.
7 . The method of claim 1 , wherein the microstripline based hybrid coupler has height between 1.4 mm and 1.7 mm.
8 . The method of claim 1 , wherein the microstripline based hybrid coupler has relative permittivity between 2.42 and 2.68.
9 . The method of claim 1 , wherein the microstripline of the multi-resonance transmit/receive (T/R) switch does not exceed a threshold trace width of 0.55 mm.
10 . The method of claim 1 wherein the RF input signal is transmitting in a range 74-130 MHz or a range 280-332 MHz to the MRI RF coil.
11 . The method of claim 1 , wherein the RF signal transmits through the microstripline based hybrid coupler with an insertion loss less than-0.64 dB.
12 . The method of claim 1 , wherein the RF signal transmits through the microstripline based hybrid coupler T/R switch with a return loss less than-15 dB.