Tuneable microstrip device controlled by a weak magnetic field using ferromagnetic laminations

The properties of lamellar insulator ferromagnetic on the edge (LIFE) material in a microwave device under a static field are studied. The LIFE composite is manufactured by gluing sheets of a ferromagnetic thin film deposited by physical vapor deposition on a polymeric substrate. The 0.154-mu m-thick ferromagnetic material is an amorphous CoNiZr alloy deposited on a 12.7-mu m-thick kapton film. According to gyromagnetic model, when an external static field is applied along the easy axis, the gyromagnetic resonance frequency is shifted towards high frequencies. Then, a piece of LIFE composite was integrated in a microstrip line, using a substrate of low permittivity. The displacement of the minimum of the transmission coefficient in the microstrip line due to a static field applied is presented. The operation of a microwave filter with a stopband tuneable in the 2-6 GHz range by a small static magnetic field (< 500 Oe) is demonstrated, as well as a magnetic switch. (C) 2000 American Institute of Physics. [S0021-8979(00)49608-8].