Harmonic load pull tuner with resonant prematching module
View Patent ↗A harmonic rejection load pull tuner uses a resonant pre-matching module in order to enhance the reflection factor (tuning range) at the fundamental frequency without affecting the tuning range at the harmonic frequencies. The insertion loss of the harmonic tuner itself, if such a pre-matching module is not used, reduces the tuning range, generated by a wideband tuner at the fundamental frequency, connected after the harmonic tuner. In order to re-establish and increase the tuning range of the fundamental tuner a resonant pre-matching module is used, which increases the tuning range at the fundamental frequency and has no effect on the harmonic impedances. A wideband pre-matching module is not useful, since while it increases the tuning range at the fundamental frequency, it limits the tuning range at the harmonic frequencies.
1. A harmonic rejection load pull tuner comprising a test port and an idle port and a slotted airline (slabline) connecting both ports, said tuner uses two or more open conductive resonant stubs, of which said conductive stubs each one is mounted and fixed inside a conductive resonant cavity using low loss dielectric washers and is quarter lambda resonant at a harmonic frequency (2Fo or 3Fo) of a fundamental frequency Fo, said resonant stubs are positioned vertically relative to the slabline and make galvanic contact with the central conductor of the slabline and slide along the slabline, said tuner providing for an additional resonant pre-matching module to be inserted between the resonant stubs and the test port of said tuner.
2. A tuner as in claim 1 , which comprises a resonant pre-matching module inserted between the test port and said resonant stubs, said pre-matching module comprises an open conducive stub which is quarter lambda resonant and tuned at the fundamental frequency (Fo), said conductive stub is mounted inside a coaxial conductive cavity using low loss dielectric washers, which allow it to be moved vertically relative to the central conductor of the slabline, said coaxial cavity slides on the lateral walls of said slabline and makes continuous perfect ground contact with the said walls of the slabline.
3. A tuner as in claim 2 , in which said resonant stub of said pre-matching module has a semi-cylindrical conductive foil attached to its lower end, closest to the central conductor of said slabline and creates capacitive coupling between said resonant stub and said central conductor of said slabline, said resonant stub is attached to a vertical gear mechanism using low loss dielectric material, which positions said resonant stub at any distance from the central conductor of said slabline, in order to adjust said capacitive coupling between said resonant stub and said central conductor.
4. A tuner as in claim 3 , in which said resonant stub of said pre-matching module has its open end partially covered by a dielectric tube, which slides tightly over the open end of said open stub, said dielectric tube can be moved vertically relative to said resonant stub and adjusts the effective electrical length of said resonant stub and by consequence its resonance frequency (Fo).
5. A tuner as in claim 4 , in which the fixed contacting resonators can be moved horizontally relative to the test port of said tuner using appropriate gear and remotely controlled stepper motors, driven by a control computer running control software and make continuous and perfect galvanic contact with the central conductor of said slabline.
6. A tuner as in claim 5 , in which the pre-matching module, which includes said variable capacitively coupled stub, can be moved horizontally relative to the test port of said tuner using appropriate gear and remotely controlled stepper motors, driven by a control computer running control software and makes continuous and perfect ground contact with the lateral walls of said slabline.