Multi-resonance broadband transmit/receive switches without tuning used in magnetic resonance imaging
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 magnetic resonance imaging (MRI) apparatus, comprising:
a multi-resonance transmit/receive (T/R) switch, comprising:
a microstripline based hybrid coupler having a top plane at a top side and a bottom plane at a bottom side;
a first pin diode;
a second pin diode;
four vertical transmission lines arranged in a bended manner and six horizontal transmission lines arranged in a bended manner on the top plane of the microstripline based hybrid coupler; and
four vertical transmission lines arranged in a bended manner and six horizontal transmission lines arranged in a bended manner on the bottom plane of the microstripline based hybrid coupler;
wherein the top plane of the microstripline based hybrid coupler is associated with a first port and a second port, and electrically connected to an anode of the first pin diode and an anode of the second pin diode, the first port being coupled to a radio frequency (RF) amplifier, the second port being coupled to an MRI RF coil;
wherein the bottom plane is associated with a third port and a fourth port, and the bottom plane is electrically connected with the anode of the first pin diode and the anode of the second pin diode, the third port being coupled to an RF terminator, the fourth port being coupled to a pre-amplifier;
wherein a cathode of the first pin diode and a cathode of the second pin diode are electrically connected to ground;
wherein the multi-resonance transmit/receive (T/R) switch is configured to, during a transmit mode, place the first and second pin diodes in a forward biased state, such that RF pulses of different frequencies received from the RF amplifier coupled to the first port are directed to the MRI RF coil coupled to the second port, wherein the different frequencies are received concurrently and without tuning by the multi-resonance transmit/receive (T/R) switch from the MRI RF coil; and
wherein the multi-resonance transmit/receive (T/R) switch is configured to, during a receive mode, place the first and second pin diodes in a reverse biased state, such that RF signals detected by the MRI RF coil coupled to the second port are directed to the pre-amplifier coupled to the fourth port.
2. The magnetic resonance imaging (MRI) apparatus of claim 1 , wherein a length of at least one transmission line is between 55 cm and 105 cm.
3. The magnetic resonance imaging (MRI) apparatus of claim 1 , wherein the top plane and the bottom plane of the multi-resonance transmit/receive (T/R) switch are rectangular in shape.
4. The magnetic resonance imaging (MRI) apparatus of claim 1 , wherein the top plane and the bottom plane of the multi-resonance transmit/receive (T/R) switch are of equal sizes.
5. The magnetic resonance image (MRI) apparatus 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.
6. The magnetic resonance imaging (MRI) apparatus of claim 1 , wherein the microstripline based hybrid coupler has height between 1.4 mm and 1.7 mm.
7. The magnetic resonance imaging (MRI) apparatus of claim 1 , wherein the microstripline based hybrid coupler has relative permittivity between 2.42 and 2.68.
8. The magnetic resonance imaging (MRI) apparatus 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.
9. A magnetic resonance imaging (MRI) apparatus, comprising:
a multi-resonance transmit/receive (T/R) switch, comprising:
a microstripline (MSL) based hybrid coupler having a top plane at a top side and a bottom plane at a bottom side;
two pin diodes;
three vertical transmission lines arranged in a bended manner and four horizontal transmission lines arranged in a bended manner on the top plane of the MSL based hybrid coupler;
three vertical transmission lines arranged in a bended manner and four horizontal transmission lines arranged in a bended manner on the bottom plane of the MSL based hybrid coupler;
an inverter electrically connected to a middle vertical transmission line of the three vertical transmission lines on the top plane;
an inverter electrically connected to a middle vertical transmission line of the three vertical transmission lines on the bottom plane;
wherein the top plane of the MSL based hybrid coupler is associated with a first port and a second port, and electrically connected to anodes of the two pin diodes, the first port being coupled to a radio frequency (RF) amplifier, the second port being coupled to an MRI RF coil;
wherein the bottom plane of the MSL based hybrid coupler is associated with a third port and a fourth port, and electrically connected to the anodes of the two pin diodes, the third port being coupled to an RF terminator, the fourth port being coupled to a pre-amplifier; and
wherein cathodes of the two pin diodes are electrically connected to ground;
wherein the MSL based hybrid coupler is configured to, during a transmit mode, place the two pin diodes in a forward biased state, such that RF pulses of different frequencies received from the RF amplifier coupled to the first port are directed to the MRI RF coil coupled to the second port, wherein the different frequencies are received concurrently and without tuning by the multi-resonance transmit/receive (T/R) switch from the MRI RF coil,
wherein the MSL based hybrid coupler is configured to, during a receive mode, place the two pin diodes in a reverse biased state, such that RF signals detected by the MRI RF coil coupled to the second port are directed to the pre-amplifier coupled to the fourth port.
10. The magnetic resonance imaging (MRI) apparatus of claim 9 , wherein the top plane and the bottom plane of the multi-resonance transmit/receive (T/R) switch are rectangular in shape and of equal sizes.
11. The magnetic resonance image (MRI) apparatus of claim 9 , wherein a length of the microstripline based hybrid coupler is less than 410 mm and a width of the microstripline based hybrid coupler is less than 190 mm.