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Item type:Publication, Access status: without files , Hexagonal ferrites for self-biasing circulators integrated in LTCC microwave modules(Elsevier, 2024-10-01); ; ; ; Next-generation microwave LTCC modules for satellite communication systems require the integration of passive components including circulators to manipulate electromagnetic signals at high frequency. Substituted M-type hexagonal ferrites (Ba/Sr)ScxFe12−xO19 are applied as self-biasing microwave magnetic materials at frequencies of about 30 GHz. The ferrites are integrated into LTCC multilayer devices as sintered drop-in bulk samples. Sintered ferrites with preferential orientation of grains were fabricated by compaction of powders in a magnetic field and sintering at 1300 °C. Alternatively, screen-printed ferrite films were dried in an external magnetic field, and cofired at 900 °C. The magnetic texture of the ferrites is characterized using XRD, EBSD, and magnetic measurements. Integrated Y-type circulators were tested and exhibit non-reciprocal behavior. This indicates that hexagonal ferrites are promising candidates for self-biasing circulators embedded in LTCC microwave modules operating at Ka-band frequencies at around 30 GHz.Publicationtype: Journal Article56 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Fabrication of Self-Biased Circulators with Integrated Hexagonal Microwave Ferrites Using LTCC Technology(Göller, 2023-03); ; ; ; Publicationtype: Journal Article117 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Design Approach for an Integrated Self-Biased Ka-Band Isolator(2021-01-12); ; ; ; We present a design approach for a self-biased Ka-band isolator. A pre-sintered barium hexaferrite is integrated in a RO4003C laminate. In combination with a microstrip design this yields a compact and cost-effective component. The operating principle of the isolator and a concrete design example are presented. The experimental work confirms the theoretical expectations and reveals the optimization potential.Publicationtype: Conference Paper101 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Integration Concept for a Self-Biased Ka-Band Circulator(2020-11-16); ; ; ; This paper studies an integration concept fora self-biased Ka-band circulator. Non-reciprocity is achievedby means of a pre-sintered scandium substituted bariumhexaferrite which, as a hard-magnetic material, does notrequire external magnetic biasing. The ferrite is integratedinto a microstrip circuit on a RO4000 laminate. This yieldsa compact and potentially low-cost circulator. The basicfunctionality is demonstrated in a first experiment. Theresults are still quite preliminary, though. Yet, some importantconclusions can be drawn regarding the required designoptimization measures.Publicationtype: Conference Paper234 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Ga-, Y-, and Sc-substituted M-type ferrites for self-biasing circulators in LTCC microwave modules(American Institute of Physics (AIP), 2020-02-11); ; ; ; The partial substitution of Fe3+ by diamagnetic Me3+ in BaMexFe12-xO19 with Me = Ga and Y (0 ≤ x ≤ 2) was studied. Samples were synthesized by the mixed-oxide route and their properties were compared to BaScxFe12-xO19 ferrites. It was shown by XRD that the hexagonal lattice parameters with x for Me = Ga and Sc vary continuously. For Me = Y no single-phase ferrites were obtained indicating that the solubility limit for Y in Ba ferrite is very limited. For Me = Ga and Sc, the saturation magnetization at room temperature is reduced with x. The coercivity as well as the ferromagnetic resonance frequency remain almost unchanged for Ga-substituted ferrites, whereas for Sc-substituted ferrites the coercivity and ferromagnetic resonance frequency decrease with x. Thick films of Sc-ferrite (x = 0.5) were screen-printed onto LTCC tape substrates and post-fired at 900°C. Application of a magnetic field during drying allows fabrication of textured ferrite layers. Alternatively, ferrite tapes and LTCC tapes were successfully co-fired at 900°C.Publicationtype: Journal ArticleScopus© Citations 9 357 584