Microwave applications, property

Boron has high neutron absorption and the boron-aluminum composites are being investigated for nuclear applications. Single-ply boron-epoxy composites have microwave polarization properties with potential applications in antenna and radome designs. 01... 

Perovskites AB)/3C2/303 (A = Ba, Sr, B = Zn, Mg, Co, Ni C = Nb, Ta) are promising compounds for microwave applications. It is important to synthesize these complex oxides as pure perovskite phases because the slightest admixture of a second phase hinders drastically the dielectric properties of ceramics, which sinter only at very high temperatures (1400 to 1500°Q. The precursor chemistry resembles greatly that of BaTi03 formation by alkoxide or alkoxide-hydroxide routes. Below we summarize the 3 approaches to the synthesis of these perovskites by the sol-gel method ... 

Apart from ybco, thin films with reasonable microwave properties have been prepared from the thallium-based compounds Tl2Ba2CaCu208 (Tc 105 K) and Tl2Ba2Ca2Cu30io (Tc 115 K) [10], hts films with reasonable and qualified microwave properties nowadays can be grown on wafers up to more than 4 in diameter, the most common size are 2 and 3 for microwave applications. A very important step was the preparation of double-sided coating, which have turned out to be essential for planar microwave devices, where the metal ground plane needs to be superconducting in order to achieve high quality factors. 

The mechanisms by which microwave energy is absorbed by the entire processing system (the microwave applicator, the specimens, and the thermal insulation) are crucial to understand the microwave processing of ceramic materials. The microwave energy absorbed per unit time per unit volume, pabs (the powder density), can be related to dielectric properties of the material and to the applied electromagnetic field " ... 

Conductive polymers are causing a great interest due to their wide variety of properties. In particular, from the evolution of their conductivity with frequency, many ideas have been attempted to adapt these phenomena to microwave applications. 

The ceramic package used for microwave applications requires following properties (a) lower dielectric constant and lower loss tangent in the radio frequency... 

The useful properties of a dielectric ceramic material-that is, their figures of merit, and in particular for microwave applications (see Section 8.4)-can be described by ... 

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