Have You Used These Special Directional Couplers?
Let’s briefly take a look at some unique couplers and a few coupler patents.
No.1 Moreno Orthogonal Waveguide Coupler
This waveguide coupler consists of two waveguides at right angles to each other. Coupling occurs through two small holes on the common broad wall of the waveguides, as shown in the figure below. With optimized design, the signal power coupled through these two holes can be phase-cancelled. These holes are typically made in a small cross shape to achieve optimal performance.
No.2 Schwinger Reverse Coupler
This is also a waveguide coupler. The design of this waveguide coupler ensures that the path lengths from the coupling holes to the non-coupling ports are equal, which allows for good directivity across all frequencies. Two slots are placed on either side of the centerline of the common waveguide wall, causing the electromagnetic waves at the isolated port to cancel each other out, as shown in the figure below. The magnetic dipoles coupled by these two slots have a 180° phase difference. After a quarter-wavelength slot spacing, the two coupled signals combine in phase at the coupled port.
No.3 Riblet Short-Slot Coupler
The Riblet coupler is composed of two waveguides with a common side wall, and coupling occurs at the slot on the common side wall. In this region, both the TE10 and TE20 modes are excited. With proper design, they are phase-cancelled at the isolated port and constructively added at the coupled port. This type of coupler can be made relatively small.
No.4 Symmetrical Tapered Line Coupler
A multi-section coupled line coupler can be extended into a continuously tapered line structure, resulting in a broadband coupler. In the design, to adjust the coupling and isolation of the coupler, the line width and spacing of the entire tapered line can be optimized. This type of coupler also provides a 90° phase shift between the two output ports.
No.5 Planar Line Slot Coupler
The couplers with coupling slots mentioned above can also be applied to other microwave transmission lines, such as microstrip lines, as shown in the figure below.
This translation accurately reflects the content of the original article, with correct terminology for each type of coupler described.
Conclusion
These specialized directional couplers each offer unique benefits and are designed for specific applications in microwave and RF systems. Whether for enhancing signal isolation, achieving precise phase control, or optimizing space in compact designs, understanding the characteristics and uses of these couplers can greatly enhance the performance of your systems. As technology advances, the continued innovation in coupler designs will undoubtedly lead to even more specialized and efficient solutions.
