Active slide screw tuner
View Patent ↗An active slide screw tuner uses the forward injection technique, also called Gamma Boosting Unit (GBU) cascaded with a passive impedance tuner in the same slabline and housing. The GBU samples a portion of the forward travelling signal, adjusts its phase, amplifies it, adjusts its amplitude (attenuation) and couples it back, in reverse direction into the main signal path. In the present active tuner technique as is herein implemented, the horizontal and vertical movement of the forward coupler through remote control in a tuner-type carriage and vertical axis, eliminates the need of a separated phase shifter and attenuator, which makes the solution better, simpler and more effective.
1. An active slide screw impedance tuner, comprising
two ports, a test port and an idle port, and a slotted low loss airline (slabline) between the ports;
external amplifier having an input and an output port;
characteristic impedance (Zo) terminations;
and at least two mobile carriages, carriage #1 closest to the test port and carriage #2 closest to the idle port;
whereby
the carriages slide independently along the axis of the slabline and have, each, a vertically movable axis;
and whereby
carriage #1 has a signal coupler #1 attached on its vertical axis, which adjusts the penetration of the coupler into the slot of the slabline;
and whereby
a signal coupler #2 is inserted into the slot of the slabline at a fixed position between the test port and carriage #2;
and whereby each coupler has a coupled port and an isolated port;
and whereby the amplifier is connected to the couplers as follows:
the input port is connected to the coupling port of coupler #1 and the output port to the coupled port of coupler #2;
and whereby
carriage #2 carries on its vertical axis a reflective (tuning) probe insertable to adjustable depth into the slot of the slabline and capacitively coupled with the center conductor of the slabline;
and whereby the isolated ports are terminated with characteristic impedance (Zo);
and whereby the coupling port of each coupler is close to the test port and the isolated port of each coupler is close to the idle port.
2. The tuner as in claim 1 ,
whereby coupler #2 is inserted between carriage #1 and carriage #2.
3. The tuner as in claim 1 ,
whereby coupler #2 is inserted between the test port and carriage #1.
4. The tuner of claim 1 ,
whereby coupler #2 is attached to the body of carriage #1 at a fixed distance from coupler #1, which is attached to the vertical axis of carriage #1.
5. The tuner as in claims 3 or 4 ,
whereby the position of the carriages and their axes are remotely controlled using gear, electrical motors, control electronics, digital processor and control software.
6. The tuner as in claim 5 ,
whereby the signal couplers are wave-probes.
7. The tuner as in claim 5 ,
being divided in two distinct tuning units:
a) a passive tuning unit, comprising carriage #2 controlling the tuning probe, and
b) an active tuning unit, comprising carriage #1, couplers #1 and #2 and the amplifier;
said units being mounted in separate housings, each unit having a test port and an idle port,
and whereby both units are cascaded;
and whereby the test port of the active unit is the test port of the tuner.
8. The tuner as in claim 5 , whereby Zo is nominally 50 Ohms.
9. The tuner as in claim 4 , whereby the distance between couplers #1 and #2 is manually adjustable.
10. The tuner as in claim 1 , comprising low-, high- or band-pass filter before or behind the amplifier, for limiting spurious signal generation and propagation at harmonic frequencies.
11. The tuner as in claim 7 , whereby Zo is nominally 50 Ohms.