Slide screw impedance tuners use resonant probes in order to avoid uncontrollable reflection factors at harmonic frequencies in high power load pull transistor testing. The tuners use either coaxial slotted airlines or slablines. The probes are coupled capacitively with the central conductor of the airline and are either slotted with associated spring loaded effect for better galvanic ground contact, or solid dielectrically coated or anodized and carefully machined for slide fitting into the slabline opening or the coaxial line slot, for capacitive contact with the ground plane. The probes allow for selective reflection behavior over a given frequency range, which does not include unwanted frequencies, such as harmonic or sub-harmonic frequencies.
Impedance tuners with resonant probes / 8,358,186
Tuesday, January 22, 2013