Low frequency electro-mechanical impedance tuner / 7,646,267

Tuesday, January 12, 2010

A segmented, electro-mechanical, remotely controlled programmable impedance tuner for the frequency range between 10 and 200 MHz uses a cascade of three continuously variable mechanical capacitors interconnected by a set of two low loss flexible or semi-rigid cables; the electrical length of the interconnecting cables between the capacitors determines the frequency at which tuning coverage of the entire area of the Smith chart is optimum; for maximum impedance coverage the length is to be chosen such as to generate a transmission phase shift of 60 degrees at the center frequency between each capacitor stage. Remote tuning is possible by changing the value of the capacitors using electrical stepper motors. The tuner is calibrated using a vector network analyzer and the data are saved in the memory of the control computer, which then allows tuning to any user defined impedance within the tuning range. Reflection factor values between 0 and higher than 0.9 can be obtained using this tuner.