Miniaturization and enhancement performance of passive microwave components using HTS and thin film ferroelectric materials

Passive RF/microwave components (e.g. couplers, and filters) occupy big design area in the RF/microwave circuit and systems, especially when it work at low frequencies. This paper presents using of High Temperature Superconductor HTS for reducing the size of circuit design and maintains good performance, the surface impedance model is investigated and verified, branch-line coupler is designed on Lanthanum Aluminate (LaAlO₃) substrate which is more suitable for HTS, the CST Electromagnetic wave simulator is used for design the coupler, all parameters of the designed coupler (Insertion Loss, Return Loss, and Isolation) show good enhancement when compared to previously published result of the coupler made of copper material. Also the size of the HTS coupler is small four times than the coupler made of copper material. A tunable frequency branch-line coupler is designed by using thin film layer of Strontium Titanate(SrTiO3) ferroelectric material, the thin layer is sandwiched between the LAO substrate and HTS microstrip line, the response shows a variation of frequency work with changing applied electric field.