A magnetic resonance imaging (MRI) for outdoor in-situ scanning is promising for biological studies. Here we propose a portable MRI system in which both the magnet array and the transceiver coil can be physically opened and closed. This is for imaging long objects in situ where cutting the object and fitting it into a bore for scanning is not an option. A convertible magnet array is designed where the force to open and to close the magnet array is minimized based on an analytical solution. Meanwhile, a convertible solenoid coil is proposed as an RF transceiver coil.