An exact synthesis method for dual-band Chebyshev impedance transformers

We propose an exact synthesis method which allows the design of dual-band transformers with an arbitrary even number of uniform sections giving equi-ripple impedance matching in two separate bands centered at two arbitrary frequencies. This method is a generalization of the exact Collin-Riblet synthesis of Chebyshev single-band transformers. As compared to a single-band Collin-Riblet transformer encompassing both required passbands, the proposed design yields significantly better performance in terms of passband tolerance and width.