What is directional coupler theory?
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What is directional coupler theory?
A Directional coupler is a device that samples a small amount of Microwave power for measurement purposes. The power measurements include incident power, reflected power, VSWR values, etc. Directional Coupler is a 4-port waveguide junction consisting of a primary main waveguide and a secondary auxiliary waveguide.
How does a dual directional coupler work?
A dual directional coupler, can be thought of as two directional couplers placed back to back, with both the isolated ports of each coupler terminated to 50 ohms (or the system impedance).
What is the main application of directional coupler?
A directional coupler is used for isolating, eliminating or combining signals in microwave signal routing and radio frequency. The ports in the directional coupler are: Coupled. Input.
What will be the spacing between Centres of two holes in directional coupler and why?
Two-Hole Directional Coupler This is a directional coupler with same main and auxiliary waveguides, but with two small holes that are common between them. These holes are a λg/4 distance apart where λg is the guide wavelength.
What are characteristics of directional coupler?
An essential feature of directional couplers is that they only couple power flowing in one direction. Power entering the output port is coupled to the isolated port but not to the coupled port. A directional coupler designed to split power equally between two ports is called a hybrid coupler.
What are the parameters of directional coupler?
5.8: Directional Coupler
| Parameter | Ideal | Typical |
|---|---|---|
| Coupling, C | − | 3−40 dB |
| Transmission, T | |√1−1/C2| | −0.5 dB |
| Directivity, D | ∞ | 40 dB |
| Isolation, I | ∞ | 40 dB |
What are the properties of directional coupler?
Common properties desired for all directional couplers are wide operational bandwidth, high directivity, and a good impedance match at all ports when the other ports are terminated in matched loads.
How does a hybrid coupler work?
A hybrid coupler is a four port directional coupler that splits an input signal equally between two output ports, with an attenuation of 3 dB. The signals at the outputs have a 90 degree or 180 degree phase difference between them.
What are the properties of directional couplers?
What are the two types of directional coupler?
There are two types of directional couplers; both are four-port components and are reciprocal.
- Two-hole directional coupler.
- Single-hole or Bethe-hole directional coupler.
Which type of device is a directional coupler?
signal processing device
Directional couplers are an important type of signal processing device. Their basic function is to sample RF signals at a predetermined degree of coupling, with high isolation between the signal ports and the sampled ports — which supports analysis, measurement and processing for many applications.
How do you measure directional coupler?
Measurement Procedure
- Connect the spectrum analyzer inputs to the isolated and coupled ports on the directional coupler.
- Set the low-end frequency on your source and input this into the feedline.
- Measure the magnitude of the wave voltages at the coupled and isolated ports.
What is the coupling factor?
The coupling factor is defined as the square root of the ratio between the converted and the stored energy.
What is a coupling factor?
What are the scattering parameters of directional coupler?
A directional coupler is a four-port device that uses waveguides to distribute power. A directional coupler is characterized by its coupling factor, isolation, and directivity. The scattering matrix of a directional coupler is the most convenient representation of its behavior in complex systems.
What is the difference between directional coupler and hybrid coupler?
What does a coupler do?
A two-part device called a coupler lets you use different decorating tips with the same bag of icing, creating several designs with the same color and consistency.
What is the isolation of a coupler?
Isolation of a directional coupler can be defined as the difference in signal levels in dB between the input port and the isolated port when the two output ports are terminated by matched loads, or: Isolation can also be defined between the two output ports.
What are performance characteristics of directional coupler?
Performance characteristics: Coupling Factor: This indicates the fraction of the input power (at P1) that is delivered to the coupled port, P3. Directivity: This is a measure of the coupler’s ability to separate waves propagating in forward and reverse directions, as observed at the coupled (P3) and isolated (P4) ports.
What is the ratio of coupling?
The Coupling factor/Coupling Ratio is the ratio of incident power to the coupled power, measured in dB. So when we say a coupler has a coupling value of 3 dB, it means that 50% of the power is coupled to the coupled port of the coupler and the rest of the power is routed to the output port of a coupler.
