A dual‐band Chebyshev impedance transformer

This paper presents a simple extension of the Chebyshev quarter‐wave multisection transformer synthesis to dual‐band operation. The method is a variation of the classical Chebyshev transformer design procedure, using a suitable 2nd‐order trigonometric polynomial as the argument of the Chebyshev polynomial. As compared to a single‐band Chebyshev transformer encompassing both required passbands, the proposed design yields significantly better performance.