Microwave ferrites for phase shifters

The electronically steerable phased array radars (PARs) are finding extensive use in military, communication and civilian applications. A PAR system typically comprises a regular arrangement of a large number of phase controlled radiating elements. Ferrite-based phase shifters in various designs are employed in these systems operating at frequencies above 5 GHz due to their superior power rating and insertion loss characteristics. Under DRDO’s integrated missile programme considerable success has been achieved in the country on the development of ferrite materials, phase shifters and array system. The work done at SSPL on the development of ferrite materials for both X- and C-band phase shifters is described. The effect of various substituents in the chemical composition of the lithium-titanium ferrites and of the process parameters to evolve the grades with required magnetic, electrical and microstructural properties are discussed. The investigations carried out to enhance optimally the r.f. power handling capability of the material for meeting the desired specifications of the C-band phase shifter are also given.