Characteristic in the 0.01 GHz-2.6 GHz range of film transformer with coils on both sides of flexible polyamide film

Two meander planar thin film transformers were fabricated using microlithography on a flexible polyamide film surface. One transformer was fabricated on the same polyamide surface (single sided transformer). The other transformer had coils which were placed on either side of the polyamide surface (double sided transformer). The output characteristics of these thin film transformers were measured using a spectrum analyzer in the frequency range from 0.01 GHz to 2.6 GHz and compared to the output characteristics obtained by simulating the transformer using a distributed parameter circuit theory. The simulated results for a single sided transformer agreed well with the measured results. On the other hand, the simulated results obtained using a double sided transformer did not fit the measured results for frequency above 1 GHz