A varactor tunable complex impedance transformer

We have conceived and realized a microwave tunable transformer. The tunability is obtained by loading a transmission Line by reverse biased Schottky diodes acting as voltage variable capacitances. Only two diodes pairs are necessary to obtain impedance tunability between 5 R to 300 R, with an operating frequency varying of more than k 10 %. Complex loads can also be matched witb a wide covering of the Smith chart, but small bandwidth of about 2%. Tbe device length is around a third of the guided wavelength.