Sub-THz vector load pull tuner
View Patent ↗Wideband waveguide slot-based bi-directional couplers are combined with waveguide load pull tuners for true vector load pull at sub-THz frequencies. Coupling is constant and Directivity is above average up to 170 GHz and can be extended to 330 GHz and are controlled by the shape, size, and configuration of the slots between the main tuner waveguide and the adjacent coupler waveguide. A calibration method allows full characterization of the coupler-tuner assembly.
1. A waveguide vector load pull tuner comprising:
a four-port assembly of a waveguide load pull tuner and a bi-directional waveguide signal coupler,
wherein
the waveguide load pull tuner comprises:
a main rectangular waveguide having an input (test) port, an output (idle) port, a slot along a longitudinal axis of the main waveguide, and
a remotely controlled conductive tuning probe, insertable perpendicularly into the slot between a state of withdrawal and a state of maximum penetration and movable inside the slot along the main waveguide over at least one half of a wavelength at a lowest frequency of operation of the waveguide vector load pull tuner,
and wherein
the bi-directional waveguide signal coupler comprises:
a secondary rectangular waveguide terminating at a coupled and an isolated port touching the main waveguide at a shared wall region and communicating electro-magnetically with the main waveguide via a number of holes traversing the shared wall region of the main and the secondary waveguides,
and wherein
the slot of the main waveguide, in which the tuning probe penetrates, is placed between the idle port and the holes traversing the shared wall region
and a calibration method of the waveguide vector load pull tuner using a two-port vector network analyzer (VNA);
and a calibration method of the waveguide vector load pull tuner using a four-port vector network analyzer (VNA);
said calibration methods generating and saving s-parameters of the vector load pull tuner four-port assembly as a function of frequency and a multitude of horizontal and vertical positions of the tuning probe.
2. The waveguide vector load pull tuner of claim 1 ,
wherein
the main and the secondary waveguides have a rectangular cross section with two broad walls and two narrow walls,
and wherein
a broad wall of the secondary waveguide is touching a broad wall of the main waveguide.
3. The waveguide vector load pull tuner of claim 1 ,
wherein
the main and the secondary waveguides have a rectangular cross section with two broad walls and two narrow walls,
and wherein
a narrow wall of the secondary waveguide is touching a broad wall of the main waveguide section.
4. The waveguide vector load pull tuner of claim 1 ,
wherein
the holes traversing the shared wall region of the main and the secondary waveguides are round.
5. The waveguide vector load pull tuner of claim 1 ,
wherein
the holes traversing the shared wall region of the main and the secondary waveguides are rectangular slots.
6. The waveguide vector load pull tuner of claim 1 ,
wherein
the holes traversing the shared wall region of the main and the secondary waveguides are parallelogram slots.
7. The waveguide vector load pull tuner of claim 1 ,
wherein
the holes traversing the shared wall region of the main and the secondary waveguides are rectangular polygon slots having a wide section and a narrow section.
8. The waveguide vector load pull tuner of claim 1 ,
wherein
the holes traversing the common wall region of the main and the secondary waveguides are slots having the shape of a cross.
9. The calibration method for the waveguide vector load pull tuner as in claim 1 , using a two-port vector network analyzer (VNA) having ports 1 and 2, pre-calibrated at a frequency F,
comprising the following steps:
a) the test and idle ports are connected to ports 1 and 2 of the VNA while the coupled and isolated ports are terminated with characteristic impedance (Zo);
b) two-port s-parameters Sij for {i, j}={1,2} are measured at the frequency F for a multitude M=N×K of N horizontal (X) and K vertical (Y) positions of the tuning probe and saved in file A12 in the format Sij(X,Y);
c) the test port and the coupled port are connected to ports 1 and 2 of the VNA while the idle port and the isolated port are terminated with characteristic impedance (Zo);
d) two-port s-parameters Sij for {i, j}={1,2} are measured at the frequency F for the multitude M=N×K of the N horizontal (X) and the K vertical (Y) positions of the tuning probe and saved in file A13 in the format Sij (X,Y);
e) the test port and the isolated port are connected to ports 1 and 2 of the VNA while the idle port and the coupled port are terminated with characteristic impedance (Zo);
f) two-port s-parameters Sij for {i, j}={1,2} are measured at the frequency F for the multitude M=N×K of the N horizontal (X) and the K vertical (Y) positions of the tuning probe and saved in file A14 in the format Sij (X,Y);
g) the idle port and the coupled port are connected to ports 1 and 2 of the VNA while the test port and the isolated port are terminated with characteristic impedance (Zo);
h) two-port s-parameters Sij for {i, j}={1,2} are measured at the frequency F for the multitude M=N×K of the N horizontal (X) and the K vertical (Y) positions of the tuning probe and saved in file A23 in the format Sij (X,Y);
i) the idle port and the isolated port are connected to ports 1 and 2 of the VNA while the test port and the coupled port are terminated with characteristic impedance (Zo);
j) two-port s-parameters Sij for {i, j}={1,2} are measured at the frequency F for the multitude M=N×K of the N horizontal (X) and the K vertical (Y) positions of the tuning probe and saved in file A24 in the format Sij (X,Y);
k) the coupled port and the isolated port are connected to ports 1 and 2 of the VNA while the test port and the idle port are terminated with characteristic impedance (Zo);
l) Two-port s-parameters Sij for {i, j}={1,2} are measured at the frequency F for the multitude M=N×K of the N horizontal (X) and the K vertical (Y) positions of the tuning probe and saved in file A34 in the format Sij (X,Y);
m) s-parameters Sij (X,Y) in files A12, A13, A14, A23, A24 and A34 are concatenated creating a calibration file A1234 of the vector load pull tuner.
10. The calibration method for the vector load pull tuner as in claim 1 , using a four-port vector network analyzer (VNA) having ports 1, 2, 3 and 4, pre-calibrated at a frequency F, comprising the following steps:
a) connect the test port to port 1, the idle port to port 2, the coupled port to port 3 and the isolated port to port 4;
b) measure six sets [Aab], where {a,b}={1,2,3,4} and a≠b, A12, A13, A14, A23, A24 and A34, of two-port s-parameters Sij with {i,j}={1,2} at the frequency F and a multitude M=N×K of N horizontal (X) and K vertical (Y) positions of the tuning probe and save in a calibration file A1234 in a format Sij (X,Y).
11. The waveguide vector load pull tuner of claim 1 ,
wherein
the main waveguide and the secondary waveguide are mounted parallel to each other.
12. The waveguide vector load pull tuner of claim 1 ,
wherein
the main waveguide and the secondary waveguide are mounted perpendicular to each other.
13. The waveguide vector load pull tuner of claim 1 ,
wherein
the main waveguide and the secondary waveguide are mounted at an angle between zero and 90 degrees to each other.