Frequency-Tunable Slot-Loop Antenna Based on KNN Ferroelectric Interdigitated Varactors
Auteurs
Aspe B., Castel X., Demange V., Deputier S., Bouquet V., Benzerga R., Sauleau R., Guilloux-Viry M.
Référence
IEEE Antennas and Wireless Propagation Letters, vol. 20, n° 8, pp. 1414-1418, art. no. 9442939, 2021
Description
A miniature frequency-tunable slot-loop antenna (0.128λ0 × 0.077λ0) based on ferroelectric K0.5Na0.5NbO3 (KNN) interdigitated varactors is investigated at Ku-band. KNN material has been selected among the ferroelectric oxide family because of its competitive properties for microwave applications. Its high permittivity value (ϵr ≈ 360 at 10 GHz) and its wide frequency tunability under an external static electric field Ebias make it a promising candidate for frequency-agile antennas and circuits at microwaves. The antenna prototype has been designed and elaborated on MgO substrate (ϵr = 9.8 and tanδ ≈ 10-4 at 10 GHz). Fabrication details including laser microetching process of the ferroelectric layer are also described. The center frequency of the slot-loop antenna can therefore be tuned monotonously from 15.22 to 15.97 GHz under Ebias = 88 kV/cm, leading to a frequency tunability rate equal to 4.6%. These results demonstrate for the first time the ability of the KNN material to be used for miniature tunable antennas, in comparison with BaxSr1-xTiO3, currently considered as the most relevant material for such applications.
