Abstract: A Ni ferrite sintered body comprising 48.0-50.0 mol % of Fe.sub.2 O.sub.3, 14.0-24.0 mol % of NiO and 28.0-36.0 mol % of ZnO with 50 ppm or less of P as an impurity, the sintered body having a minimum core loss of 30 kW/m.sup.3 or less at 50 kHz and 50 mT, and the segregation percentage of P in the crystal structure being 1% or less by area. The Ni ferrite sintered body preferably has an average crystal grain size of 3-30 .mu.m, the percentage of crystal grain particles larger than two times the average crystal grain size being preferably 10% or less based on the total number of the crystal grain particles in a crystal structure.

Abstract: A lumped constant non-reciprocal circuit element includes an insulator substrate, a predetermined number of conductor layers formed on a top surface of the insulator substrate for forming electrostatic capacitors, a shielding conductor layer formed on a top surface of the insulator substrate, and a conductor layer formed on a bottom surface of the insulator substrate and electrically connected to the shielding conductor layer. A magnetic member is disposed on the shielding conductor layer formed on the insulator substrate, and a predetermined number of mutually insulated central conductors are disposed on the magnetic member such that one end of each central conductor is connected to the shielding conductor layer and the other portion of each central conductor is connected to each electrostatic capacitor-forming conductor layer. Also means are provided for applying a dc magnetic field to the magnetic member.

Abstract: A chip for a magnetostatic wave device comprising; a base substrate consisting of a dielectric monocrystalline base plate and a ferrimagnetic monocrystalline film formed on the base plate; an excitation means for magnetostatic waves formed on the ferrimagnetic film when it is given a bias magnetic field and high frequency electric signals; and a reflection means to reflect the excited magnetostatic wave toward the center portion of the film before it reaches at end portions of the ferrimagnetic film.