Invited article: Dielectric material characterization techniques and designs of high-Q resonators for applications from micro to millimeter-waves frequencies applicable at room and cryogenic temperatures.

Dielectric resonators are key elements in many applications in micro to millimeter wave circuits, including ultra-narrow band filters and frequency-determining components for precision frequency synthesis. Distributed-layered and bulk low-loss crystalline and polycrystalline dielectric structures have become very important for building these devices. Proper design requires careful electromagnetic characterization of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. For example, we have developed the Whispering Gallery mode technique for microwave applications, which has now become the standard for characterizing low-loss structures. This paper will give some of the most common characterization techniques used in the micro to millimeter wave regime at room and cryogenic temperatures for designing high-Q dielectric loaded cavities.

Microwave study of tunable planar capacitors using mn-doped Ba0.6Sr0.4Tio3 ceramics.

This paper deals with the microwave study of coplanar tunable capacitors using Mn-doped Ba(0.6)Sr(0.4)TiO(3) ceramics. These ceramics are developed to improve performance at microwave frequencies (i.e., compromise between tuning capabilities and insertion losses). Interdigitated capacitors were first fabricated on thick Mn-doped BST ceramics. The capacitors showed reduced tuning factor because of a parasitic capacitance between the contact pads. The use of Mn-doped BST/ SiO(2) bilayers led to a significant enhancement of the capacitor performance (57% of agility under 200 V at 1 GHz).