Indian J. Phys. 71A (5), 585-591 (1997) IJP A — an international journal Behaviour of Mgo.g Zn0.i Mn0.i Al0.8 Fei.2 0 4+$ under the influence of X-band microwave radiation Vandan Surve and Vijaya Puri Department of Physics, Shivaji University, Kolhapur-416 004, Maharashtra, India Received 16 October 1996, accepted 24 February 1997 Abstract : The microwave transmission and reflection coefficients from 7.8 to 10,5 GHz of mixed ferrite in pellet form of composition MgQBZn01 Mn0A Al0.8 Fej 2 0 4+g of different thickness from 0 62 mm to 6.00 mm is reported in this paper. The transmittance and reflectance show a marked thickness dependency at particular frequencies where transmittance (voltage) becomes greater than one and reflectance (voltage) is also very high Presence of complex and spurious modes superimposed on the dominant mode along with crystalline distortions might be producing dimensional resonance effects in the ferrite. Keywords : Mixed ferrite, microwave transmittance, spurious modes PACS Nos. : 78.70 Gq, 75.50.Gg 1. In tro d u c tio n Ferrite elements are an important component of many microwave circuitry and non- reciprocal microwave integrated circuits. It is essential that the microwave properties of the material are known, to enable to perform the necessary trade offs in selecting specific materials. The behaviour of magnetized ferrites under the influence of d.c. magnetic field has been studied by various authors [1-5].'The static magnetic fields applied to the ferrite, influence the microwave properties. It would be more advantageous to use a non-magnetic ferrite as substrate with magnetically active zones to have non-reciprocal microwave component in truely planer form. With this in view, the preliminary study of the microwave properties of non-magnetic mixed ferrite was undertaken. Understanding the microwave behaviour of bulk samples will help in proper designing of ferrite components in thin film form, as these bulk samples will be used as source for deposition of thin film ferrites. The microwave voltage transmission and reflection coefficients from 7.8-10.5 GHz of mixed