Polycrystalline 0.4 μm thick films of Ag(Ta,Nb)O3 (ATN) were grown on sapphire (Al2O3-0112, r-plane) wafers by pulsed laser deposition technique. 2 and 4 μm gap interdigital capacitors were defined by photolithography on the top of Au/Cr/ATN(0.4μm)/Al2O3 film structures. They exhibit high dielectric performance. In the frequency range of 1 kHz to 1 MHz dielectric permittivity shows frequency dispersion as low as 3.5 %, loss tangent ∼ 0.0035 @ 1 MHz, Kfactor = tunability/tan δ is about 20.2 @ 200 kV/cm, and resistivity as high as 1.8 × 1011 ×cm @ 100 kV/cm. C-V and I-V characteristics recorded in time domain revealed slow Curie-von Schweidler-type relaxation of the polarization. Low frequency dispersion and loss, high tunability and low noise in the biased state promise thin ATN film capacitors for microwave applications.