Offset block waveguide coupler
A waveguide coupler includes a waveguide having a first and a second port, and a slot formed in a broadwall of the waveguide between the first and second ports, the slot centered on the first broadwall. A plurality of shifted waveguide sections are arranged between the first and second ports and extend along a length of the waveguide. A parallel-plate transmission line structure is coupled to the slot, wherein RF signals within one of the waveguide or the parallel-plate transmission line are communicated to the other of the waveguide and the parallel-plate transmission line through the slot.
1. A waveguide coupler, comprising:
a waveguide including
i) a first and a second port;
ii) a first slot formed in a first broadwall of the waveguide between the first and second ports, the first slot centered on the first broadwall;
iii) a plurality of shifted waveguide sections arranged between the first and second ports and extending along a length of the waveguide; and
a first parallel-plate transmission line structure coupled to the first slot, wherein RF signals within one of the waveguide or the parallel-plate transmission line are communicated to the other of the waveguide or the parallel-plate transmission line through the slot.
2. The waveguide coupler according to claim 1 , wherein each shifted waveguide section includes an alternating arrangement of ascending or descending steps.
3. The waveguide coupler according to claim 2 , wherein the alternating arrangement of ascending or descending steps is formed at least partially on sidewalls of the waveguide, and each step on a first sidewall of the waveguide is offset along a length of the waveguide from a step on a second sidewall of the waveguide, the second sidewall opposite the first sidewall.
4. The waveguide coupler according to claim 1 , wherein each shifted waveguide section comprises at least one step having a step width and a step height, and each step of the plurality of shifted waveguide sections has the same step width and step height as other steps of the plurality of shifted waveguide sections.
5. The waveguide coupler according to claim 1 , wherein each shifted waveguide section comprises at least one step having a step width and a step height, and at least one step of the plurality of shifted waveguide sections has a different step width or step height from other steps of the plurality of shifted waveguide sections.
6. The waveguide coupler according to claim 4 , wherein the step width corresponds to a quarter wavelength of an RF signal propagating through the waveguide.
7. The waveguide coupler according to claim 1 , wherein the waveguide a-dimension of the waveguide coupler is constant throughout.
8. The waveguide coupler according to claim 1 , wherein the plurality of shifted waveguide sections approximate a sinusoidal profile in the waveguide coupler.
9. The waveguide coupler according to claim 1 , wherein the waveguide a-dimension of the waveguide coupler varies.
10. The waveguide coupler according to claim 1 , wherein the second port comprises a load that attenuates an RF signal propagating in the waveguide.
11. The waveguide coupler according to claim 1 , wherein the second port comprises a short that electrically connects the first sidewall to the second sidewall.
12. The waveguide coupler according to claim 1 , wherein the waveguide coupler comprises a dielectric material.
13. The waveguide coupler according to claim 12 , wherein the dielectric material comprises one of a solid dielectric or an air dielectric.
14. The waveguide coupler according to claim 1 , further comprising a plurality of tuner features formed in at least one of the first broadwall or a second broadwall of the waveguide.
15. The waveguide coupler according to claim 14 , wherein the tuner features are at least partially formed in at least one of the shifted waveguide sections.
16. The waveguide coupler according to claim 1 , further comprising a second slot formed a second broadwall of the waveguide, the second broadwall arranged opposite the first broadwall.
17. The waveguide coupler according to claim 16 , further comprising a second parallel-plate transmission line structure coupled to the second slot to communicate RF signals between the waveguide and the parallel plate transmission line.
18. The waveguide coupler according to claim 1 , wherein each port comprises an electrical short circuit, further comprising a plurality of input waveguides coupled to a second broadwall of the waveguide, wherein at least one shifted waveguide section of the plurality of shifted waveguide sections is arranged between adjacent input waveguides.
19. The waveguide coupler according to claim 18 , wherein virtual shorts are formed at boundaries between adjacent input waveguides.
20. A method of launching a desired uniform or non-uniform Radio Frequency (RF) field-distribution from a waveguide into an open parallel-plate transmission line structure, wherein the waveguide is coupled to the parallel-plate transmission line via a continuous slot centered in a broadwall of the waveguide, the method comprising using shifted waveguide sections in the waveguide to perturb the RF field distribution in such a way as to couple RF energy via the continuous slot in order to create a desired e-field distribution in the parallel-plate section.