International audienceThis work deals with the design, realization and characterization of a miniature and frequency agileantenna based on a ferroelectric Ba0,80Sr0,20TiO3 thinfilm. The notch antenna is loaded with a variablemetal/insulator/metal (MIM) capacitor and is achieved by a monolithic method. The MIM capacitance is3.7 pF, which results in a resonant frequency of 670 MHz compared to 2.25 GHz for the unloadedsimulated antenna; the resulting miniaturization rate is 70%. The characterization of the antennaprototype shows a frequency tunable rate of 14.5% under an electricfield of 375 kV/cm, with a tunabilityperformance h = 0.04

Wet chemical etching of (Ba1-xSrx)TiO3 (BST) thin films has been investigated. The etchant was prepared from buffered hydrofluoric acid (BHF) and nitric acid (HNO3), BHF being the reactive agent while HNO3 acts as a catalyst. X-ray diffraction and energy dispersive X-ray spectrometry were performed in order to qualitatively and quantitatively follow the etching process. Scanning electron microscopy and a profilometer were used for determining the etching quality. The ferroelectric thin films were elaborated by a modified sol-gel process and by spin-coating on insulating (Si-wafers) or metal (stainless steel) substrates. Classic photolithography technique and a positive photo resist were used for the transfer of the patterns. Appropriate water dilution reduces the etching speed, thus allowing a better visual control of the process.

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Advanced dielectric spectroscopy enables studying of the ferroelectric complex permittivity. Interpretation with the hyperbolic law provides a better fundamental understanding of the material's tunability: bulk contribution, domain wall vibration and displacements may be discerned. Applications, like mobile telecommunication terminals may profit for the design of miniaturized and tunable antennas. As an example, conception and realization of a notch slot antenna with an integrated ferroelectric thin film varactor is presented.