Switch-isolated single-circuit q-spoiling and preamp decoupling

A radio frequency (RF) receive circuit for use in a magnetic resonance imaging (MRI) scanner, the RF circuit comprising:

• an antenna including multiple reactive impedance elements electrically coupled in a loop configuration;
• an amplifier input impedance;
• a first transmission line including a first end portion and a second end portion, wherein at least one reactive impedance element is electrically coupled in parallel with the first transmission line at the first end portion of the first transmission line;
• a second transmission line including a first end portion and including a second end portion electrically, wherein the amplifier input impedance is electrically coupled in parallel with the second transmission line at the second end portion of the second transmission line;
• a first reactive impedance circuit electrically coupled to the first transmission line and with the second transmission line, between the second end portion of the first transmission line and the first end portion of the second transmission line;
• an RF switch circuit electrically coupled in parallel with the first transmission line and the second transmission line, between a first combined impedance, that includes the first transmission line and the first reactive impedance circuit, and a second combined impedance, that includes the second transmission line and the amplifier input impedance;
• wherein the RF switch circuit is operable to electrically isolate the second combined impedance from the first combined impedance when the RF switch is closed and to electrically couple the second combined impedance to the first combined impedance when the RF switch is open;
• wherein, when the RF switch is closed, the first combined impedance transforms impedance of the RF switch circuit seen at the first end portion of the first transmission line to be in resonance with the at least one antenna impedance element;
• and
• wherein, when the RF switch is open, the first combined impedance and the second combined impedance together transform of the amplifier input impedance seen at the first end portion of the first transmission line to be in resonance with the at least one antenna impedance element.