Abstract: A method for implementing a switching between a body coil and a head coil in a nuclear magnetic resonance imaging system comprising the body coil, the head coil and a power amplifier component, wherein the power amplifier component comprises sets of power amplifiers, each set of power amplifiers comprising channels of power amplifiers combined by a Wilkinson circuit, a combiner configured to combine signals from the sets of power amplifiers and to connect the sets of power amplifiers to the body coil, a first switching device comprising a first terminal configured to be grounded, a second switching device connected in series in a resistor branch of the Wilkinson circuit, and a ¼ wavelength transformation transmission line located between the second switching device and the head coil, the method comprising connecting the power amplifier component to the body coil or the head coil by setting states of both switching devices.

Abstract: Embodiments of the present invention relate to the technical field of RF circuits, and in particular, to a balun. In an embodiment of the present invention, a balun is provided which comprises at least two coaxial cables, each of which is wound into at least one loop, and the inner and outer conductors of one end of all coaxial cables are connected respectively to each other and the inner and outer conductors of the other end are also connected to each other. The novel balun according to the embodiments of the present invention has a small size but a large power capacity and low cost, and can be used in a magnetic field environment.