Multi-band low frequency impedance tuner
View Patent ↗A multi-band, electro-mechanical programmable impedance tuner for the frequency range between 10 and 200 MHz uses cascades of three or more continuously variable mechanical capacitors interconnected with sets of low loss flexible or semi-rigid cables; for each frequency band a different set of cables and capacitors are used. The cables and/or variable capacitors inside each tuning block are switchable manually or remotely. Multi-section variable capacitors are also used. Instantaneous impedance tuning is effectuated by changing the state 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 at all frequency bands.
1. A two-segment variable parallel blade rotary capacitor comprising a first capacitance segment and a second capacitance segment,
said segments comprising a multitude of parallel metallic blades each and are divided in two sets, a first set being mounted on rotating axis and a second set being mounted on a fixed body,
said blades being inserted parallel to each other interdigital,
whereby rotation of said axis allows the overlapping area between said sets of blades to vary between a minimum and a maximum value,
and whereby said rotating axis is split in two coaxial sections, each said section rotating independently and controlling one set of blades of said capacitor.
2. A capacitor as in claim 1 , whereby each section of said coaxial axis is attached to an electric stepper motor,
said motor being remotely controlled by a control processor.