Novel design method of a multi-section transmission-line transformer using genetic algorithm techniques

A novel design method of a multi-section transmission-line transformer (TLT) for simultaneously matching multi-arbitrary frequencies and an arbitrary load is developed, based on an ideal transmission-line circuit mode and optimization design using genetic-algorithm techniques. Optimum design equations of the TLT are derived, and the related algorithm and procedure are described. In order to test and verify validity of the method, an three-section transmission-line transformer (TLT) for matching three arbitrary frequencies and an arbitrary load, is designed and analyzed by letting f
₁
=0.9 GHz, f
₂
=1.8 GHz, and f
₃
=2.4 GHz with matching Z
₀
=50 to Z
_L
=30 Omega, 75 Omega, and 100 Omega, respectively. And excellent agreement between the numerical results and the result presented by Michai is shown. The new design method avoid completed and closed - form design equations. Further, by this method, a four-section transmission-line transformer (TLT) for simultaneously matching four operating frequencies, i.e., 0.9 GHz, 1.8 GHz, 2.4 GHz, and 3.7 GHz, at different transforming ratio values, is designed and simulated effectively.