Keramički dielektrici u mikrotalasnim komponentama

摘要

Primena keramičkih materijala u mikrotalasnoj tehnici omogućava značajnu minijaturizaciju pasivnih mikrotalasnih komponenata. Ovi materijali moraju da imaju veliku relativnu dielektričnu konstantu (ε_r ≥ 30), izuzetno male dielektrične gubitke i veliku temperaturnu stabilnost. Materijali koji zadovoljavaju ove uslove su keramički sistemi (Zr, Sn)TiO_4, Ba(Zn,Ta)O_3 i Ba(Mg, Ta)O_3 kao i višefazni keramički materijali Nd_2O_3-BaO-TiO_2-Bi_2O_3 i (Ba, Sr)O-Sm_2O_3-TiO_2. Njihova zajednička karakteristika je mogućnost projektovanja konačnih osobina materijala promenom sastava keramike i definisanja procesa sinterovanja. Opisani materijali se mogu koristiti ne samo za dielektrične rezonatore i koaksijalne rezonatore ispunjene keramikom, već i za dielektrične supstrate mikrotalasnih integrisanih kola.%High frequency ceramic dielectrics are very attractive ones since their use in microwave components enables the miniaturization of passi ve microwave components. The main characteristics of these ceramic dielectric are a high dielectric constant (ε_r ≥ 30 ), low dielectric losses and temperature independent resonance frequency. The most important groups of these ceramic systems which fulfil these requirements are (Zr, Sn)TiO_4, Ba(Zn, Ta) O3, (Mg, Ta) O_3 as well as Nd_2O_3 - BaO-TiO_2-Bi_2O_3 and (Ba, Sr)O-Sm_2O_3- TiO_2. The great advantage of microwave dielectrics is the possibility to control the composition, structure and sintering conditions, so that a tailored set of properties for demanding applications could be achieved. Microwave ceramics could be used for ceramic microwave resonators, coaxial-line resonators and high permittivity dielectric substrates.