Ferroelectric Thick Film Ceramics for Tunable Microwave Coplanar Phase Shifters

Abstract

This paper introduces the processing and characterization of ferroelectric Barium-Strontium Titanate (BST) Ba^Sn-xTiOa thick film ceramics on AI 2 O 3 -microwave substrates. Applying a static interdigital capacitor model, the dielectric material properties of several different BST-thick films were determined by measurements of interdigital capacitors at 100 kHz and 1 MHz, and at room temperature of about 20 °C. Based upon different BSTthick films, microwave phase shifters in CoPlanar Waveguide (CPW) technology, qualified for cost-effective planar phased array antennas, were realized and measured at room temperature. The relative permittivity and the dielectric loss tangent of the BST films were assessed at K-band frequencies, utilizing an enhanced quasi-static CPW model for multilayer dielectric substrates. ÜbersichtDieser Beitrag stellt die Herstellung und Charakterisierung von ferroelektrischen Barium-Strontium-Titanat (BST) Ba x Sri_JiO 3 Dickschicht-Keramiken auf AI 2 O 3 -Mikrowellensubstraten vor. Unter Verwendung eines statischen Modells für Interdigitalkapazitäten wurde eine Materialcharakterisierung durch die Messung von Interdigitalkondensatoren bei Raumtemperatur sowie bei 100 kHz und 1 MHz vorgenommen. Auf der Basis des Dickschicht-BST-Materialkonzeptes wurde ein Mikrowellen-Phasenschieber in Koplanarleitungstechnik (CPW) realisiert und bei Raumtemperatur vermessen, der für den kostengünstigen Einsatz in planaren phasengesteuerten Antennen geeignet ist. Die relative Permittivität und der dielektrische Verlustfaktor des BST-Films im K-Band wurden mit Hilfe eines erweiterten quasi-statischen CPW-Modells für mehrschichtige dielektrische Substrate abgeschätzt.Für die Dokumentation Ferroetektrika / BST / Dickschicht-Keramik / Interdigitalkapazität / Koplanarteitung / Phasenschieber

Structural and dielectric properties of barium strontium titanate produced by high temperature hydrothermal method

“…The lattice parameters of the calculated spectra were then matched against the JCPDS files (PDF numbers 79-2265, 34-0411, 44-0093, 39-1395 and 79-0175) to derive the Ba content x in Ba x Sr 1−x TiO 3 compounds [11]. In order to use this structural analysis, a few assumptions were made: (1) XRD peaks were considered as double peaks if their maximum did not coincide with their gravity centre, (2) Relative area under the calculated peaks S 1 /S 2 reflected the relative amount of the phases and (3) Vegard's law could be used for calculating x parameters of the phases. This method is suitable for qualitative analysis and not to be used as a quantitative analysis.…”

“…BST with a high dielectric constant and low dielectric loss finds application as capacitors [1]. BST with a reasonably low dielectric constant, low dielectric loss and high tunability is a potential candidate in phase shifters applications [2,3]. Recently, it was found that paraelectric BST has a potential to be used in microwave devices [4,5].…”

Investigation of BZT thin films for tunable microwave applications

“…To obtain the values of ε r and tanδ, capacitance and loss measurements of interdigital capacitors (IDC) were carried out, as described in Ref. 13,6 .…”

Annealing Effects on Structural and Dielectric Properties of Tunable BZT Thin Films

“…To obtain the values of ε r and tanδ, capacitance and loss measurements of interdigital capacitors (IDC) were carried out, as described in [15]. The IDC, as shown in Fig.…”