Co-firing of low firing temperature dielectric materials with high bismuth garnet ferrites for miniaturized isolators and circulators

A method of forming a composite material for use as an isolator or circulator in a radiofrequency device, the method comprising:

• providing a low temperature fireable outer material, the low temperature fireable outer material having a garnet or scheelite structure;
• inserting a high dielectric constant inner material within an aperture in the low temperature fireable outer material, the high dielectric constant inner material having a dielectric constant above 30;
• and
• co-firing the lower temperature fireable outer material and the high dielectric constant inner material together at temperature between 650-900° C. to shrink the low temperature fireable outer material around an outer surface of the high dielectric constant inner material to form an integrated magnetic/dielectric assembly without the use of adhesive or glue.