This paper presents a soft low dielectric loss thermoplastic blend based on polyolefins as a dielectric material for microwave applications. To determine the dielectric properties, more precisely the relative permittivity εr and tan δ, characterization techniques and the elaboration of samples were customized to the 200-μm thick dielectric film. Dielectric properties were extracted from the peaks of the transmission coefficient S 12 measured from 10 MHz to 40 GHz with probe station and coplanar waveguide ring resonator. The measured dielectric constant and loss tangent of the investigated blends were found to be around ε r ≈ 2.45 and tan δ ≈ 0.01 in X-Band. A proof of concept of a patch antenna based on the developed soft dielectric film of polypropylene (PP)-based polymer blend was also made. The measured return loss of the antenna showed great agreement with simulation results with HFSS® software and reached -30 dB at an operating frequency of 9.7 GHz. An investigation of the radiation characteristics in the far field in anechoic room was made. The gain and the efficiency of the patch microstrip antenna, which were extracted and calculated from the radiation pattern attained 4.56 dB and 47% respectively. These here reported results are promising for the development of blend compositions for high frequency applications.