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Directional coupler s matrix

directional coupler s matrix

Directional Coupler is a 4 port device which has primary and secondary waveguides. The primary wave guide is from port 1 to port 2 and secondary waveguide is from port 3 to port 4. The properties of a directional coupler are, 1. All the ports are matched. When the power moves from port 1 to port 2, little portion of it would gets coupled to port 4 and not to port 3. When the power moves from port 2 to port 1, little portion of it would gets coupled to port 3 and not to port 4.

The coupling factor of a directional coupler is the ratio of incident power to forward power. The forward waves in port 4 are in the same phase and are added. He is a person who wants to implement new ideas in the field of Technology.

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Search This Blog. Semiconductors - Classification, Types, Band Theory. We know that the basic building blocks of all electronic circuits are devices having controlled flow of electrons.

Such devices are mostly v In TTL circuits also, input transistor T 1 is a multi-emitter transistor driving the phase-splitter transistor T 2. As stated above, this Optical Communication Lab - Viva Questions. What is the basic structure of a modern optical fiber?This website uses cookies to deliver some of our products and services as well as for analytics and to provide you a more personalized experience. Click here to learn more. By continuing to use this site, you agree to our use of cookies.

We've also updated our Privacy Notice. Click here to see what's new. Vertical coupling using a diffraction grating is a convenient way to couple light into an optical waveguide. Several optimization approaches have been suggested in order to design such a coupler; however, most of them are implemented using algorithm-based modelling.

In this paper, we suggest an intuitive method based on S-matrix formalism for analytically optimize 3-port vertical grating coupler devices. The suggested method is general and can be applied to any 3-port coupler device in order to achieve an optimal design based on user constrains. The simplicity of the model allows reduction of the optimization to two variables and the location of an absolute optimal operation point in a 2D contour map.

We further apply our model to a previously reported high contrast uni-directional grating coupler device and show that additional improvement in the coupling efficiency is achievable for that layout. Andrew Michaels and Eli Yablonovitch Opt. Express 26 4 Express 27 18 Po Dong and Andrew G. Kirk Appl. Express 23 19 Michaels and E. Su, R. Trivedi, N. Sapra, A. Piggott, D. Vercruysse, and J.

Zhu, W. Yang, and C. Zhang, B. Huang, Z. Zhang, C. Cheng, H. Liu, H. Li, and H. Laser Technol. Gong, J. Zhang, and S. Demeter-Finzi and S.

Liu, J. Zhang, S. Wang, C. Jin, Y.Documentation Help Center. The Coupler block models four port directional couplers in a circuit envelope environment as an ideal S-parameter model. Directional couplers are used to sample forward and reflected waves propagating along a transmission line.

Directional couplers find uses in many RF design applications such as line power sensors and transmitter automatic level controls. The default option is Directional coupler. The s-parameter matrix for Directional coupler is:. In release a, the s-parameter representation of the Directional Coupler block is altered to permit a valid implementation for all specified mask values.

This implementation adds a 90 degree phase shift to s12, s13, s21, s24, s31, s34, s42, and s43 terms. In addition, a phase shift is added to the s14, s23, s32 and s41 terms. The s-parameter matrix for the Magic tee is:. Fraction of input signal power coupled to output port of the Directional couplerspecified as a nonnegative and real scalar.

The default value is 0 dB. To enable this parameter, select Directional coupler in Select component tab. Ratio of power at coupled port to power at isolated port of the Directional couplerspecified as a nonnegative and real scalar.

The default value is inf. Loss of signal power between input and output ports of the Directional couplerspecified as a nonnegative and real scalar. Loss of signal power due to impedance mismatch of the Directional couplerspecified as a nonnegative, and real scalar.

Transmitted signal power of the Directional couplerspecified as a real scalar. The default value is 0. To enable this parameter, select Coupler symmetrical or Coupler antisymmetrical in Select component tab. Reference impedance of coupler, specified as a scalar or three-tuple. The default value is 50 Ohms. Select this parameter to ground and hide the negative terminals.

To expose the negative terminals, clear this parameter. By exposing these terminals, you can connect them to other parts of your model. Circulator Divider. Choose a web site to get translated content where available and see local events and offers.

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Directional Coupler

Other MathWorks country sites are not optimized for visits from your location. Toggle Main Navigation. Search Support Support MathWorks. Search MathWorks. Off-Canvas Navigation Menu Toggle. Trials Trials Aggiornamenti del prodotto Aggiornamenti del prodotto.Power dividers also power splitters and, when used in reverse, power combiners and directional couplers are passive devices used mostly in the field of radio technology.

They couple a defined amount of the electromagnetic power in a transmission line to a port enabling the signal to be used in another circuit. 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. Directional couplers are most frequently constructed from two coupled transmission lines set close enough together such that energy passing through one is coupled to the other. This technique is favoured at the microwave frequencies where transmission line designs are commonly used to implement many circuit elements.

However, lumped component devices are also possible at lower frequencies, such as the audio frequencies encountered in telephony. Also at microwave frequencies, particularly the higher bands, waveguide designs can be used. Many of these waveguide couplers correspond to one of the conducting transmission line designs, but there are also types that are unique to waveguide. Directional couplers and power dividers have many applications.

These include providing a signal sample for measurement or monitoring, feedback, combining feeds to and from antennas, antenna beam forming, providing taps for cable distributed systems such as cable TV, and separating transmitted and received signals on telephone lines.

The symbols most often used for directional couplers are shown in figure 1. The symbol may have the coupling factor in dB marked on it. Directional couplers have four ports. Port 1 is the input port where power is applied. Port 3 is the coupled port where a portion of the power applied to port 1 appears. Port 2 is the transmitted port where the power from port 1 is outputted, less the portion that went to port 3. Directional couplers are frequently symmetrical so there also exists port 4, the isolated port.

A portion of the power applied to port 2 will be coupled to port 4. However, the device is not normally used in this mode and port 4 is usually terminated with a matched load typically 50 ohms. This termination can be internal to the device and port 4 is not accessible to the user. Effectively, this results in a 3-port device, hence the utility of the second symbol for directional couplers in figure 1. A symbol for power dividers is shown in figure 2.

Power dividers and directional couplers are in all essentials the same class of device. Directional coupler tends to be used for 4-port devices that are only loosely coupled — that is, only a small fraction of the input power appears at the coupled port. Power divider is used for devices with tight coupling commonly, a power divider will provide half the input power at each of its output ports — a 3 dB divider and is usually considered a 3-port device.

Common properties desired for all directional couplers are wide operational bandwidthhigh directivity, and a good impedance match at all ports when the other ports are terminated in matched loads. Some of these, and other, general characteristics are discussed below. The coupling factor represents the primary property of a directional coupler. Although a negative quantity, the minus sign is frequently dropped but still implied in running text and diagrams and a few authors [4] go so far as to define it as a positive quantity.

Coupling is not constant, but varies with frequency. While different designs may reduce the variance, a perfectly flat coupler theoretically cannot be built. Directional couplers are specified in terms of the coupling accuracy at the frequency band center. The main line insertion loss from port 1 to port 2 P 1 — P 2 is:. Part of this loss is due to some power going to the coupled port and is called coupling loss and is given by:.A directional coupler is an electronic component having four-port circuits with one port being isolated from the input port and another being considered as a through port.

The device is normally used to split the input signal and distributed power. The device couples part of the transmission power by a specific factor through one port.

Directional couplers are used in a wide range of applications which involve measurement, power monitoring and other utilities. Directional couplers are categorized as passive reciprocal networks. 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:. A special design is put into use by which the input power is split between the coupled and output ports in a specific ratio known as the coupling ratio. Depending on the application for which it is used, the key specifications of the directional coupler varies. For most directional couplers, the features which are desired are high directivity, good impedance and wide operational bandwidth. But the performance of a directional coupler is computed using the directivity factor.

There are different types of directional couplers like single, dual directional, coaxial, waveguide and even combination types. Toggle navigation Menu.

Home Dictionary Tags Hardware. Directional Coupler. Definition - What does Directional Coupler mean? Techopedia explains Directional Coupler Directional couplers are categorized as passive reciprocal networks. The ports in the directional coupler are: Coupled Input Transmitted Isolated A special design is put into use by which the input power is split between the coupled and output ports in a specific ratio known as the coupling ratio.

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More of your questions answered by our Experts. Related Tags.Definition : Directional Coupler is a passive network that is used to measure the microwave power delivered to the load. It is a waveguide with 4-ports which aims at sampling of microwave power. In a nutshell, directional couplers allow the determination of delivered power to the load from the power actually being transmitted by the source. Whenever any transmitting unit transmits a certain amount of power, then for proper application it becomes necessary to have the idea about whether the complete power is received or it is some value lower or higher than the originally transmitted power.

A two-hole directional coupler is a device in which two connected waveguides have 2 holes present between them. One waveguide is known as primary main waveguide while the other is said to be the auxiliary waveguide.

Suppose a microwave signal is to be transmitted from port 1 to 2.

Power dividers and directional couplers

Further, some part of the wave proceeding towards the output gets radiated towards the auxiliary waveguide again through the second hole. Both the time the wave reaching the auxiliary waveguide travels in the forward direction i. The wave that travels in auxiliary waveguide towards port 4 will be in phase with the signal in the main waveguide and causes reinforcement of the signal.

Therefore, the signal at port 3 due to both the slots cancels each other.

directional coupler s matrix

Thus the port 3 is generally known as isolated port. Port 1 is the input and port 2 is the output port respectively. While port 4 is considered as a coupled port.

An ideal condition of directional coupler requires the backward power P b to be 0. Thus the input power gets divided in an equal manner between port 2 and 4. The 4 fundamental parameters that measure the performance of any directional coupler are as follows:. So, the coupling factor denoted as C is given as:. More simply, it is the ratio of forward coupled power to the backward power.

Thus is given as:. It is denoted by R and is given as:. The noteworthy point over here is that all the parameters of the directional couplers are measured in dB. All the four ports of the directional coupler are matched perfectly.

Derivation of a 4-port directional coupler

Thereby ensuring that no power gets reflected back towards the port. It is used to measure incident and reflected power along with measuring voltage standing wave ratio values.

It also provides the path to the signal towards the receiver and used for the purpose of unidirectional wave launching. Your email address will not be published.

Skip to content. Leave a Comment Cancel Reply Your email address will not be published.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. The following figure shows the image of a directional coupler. Directional coupler is used to couple the Microwave power which may be unidirectional or bi-directional. When the power travels from Port 1 to Port 2, some portion of it gets coupled to Port 4 but not to Port 3.

As it is also a bi-directional coupler, when the power travels from Port 2 to Port 1, some portion of it gets coupled to Port 3 but not to Port 4. If the power is incident through Port 3, a portion of it is coupled to Port 2, but not to Port 1. If the power is incident through Port 4, a portion of it is coupled to Port 1, but not to Port 2.

directional coupler s matrix

Ideally, the output of Port 3 should be zero. However, practically, a small amount of power called back power is observed at Port 3. The following figure indicates the power flow in a directional coupler. The Coupling factor of a directional coupler is the ratio of incident power to the forward power, measured in dB. The Directivity of a directional coupler is the ratio of forward power to the back power, measured in dB.

It defines the directive properties of a directional coupler. It is the ratio of incident power to the back power, measured in dB. This is a directional coupler with same main and auxiliary waveguides, but with two small holes that are common between them. The following figure shows the image of a two-hole directional coupler. A two-hole directional coupler is designed to meet the ideal requirement of directional coupler, which is to avoid back power. Some of the power while travelling between Port 1 and Port 2, escapes through the holes 1 and 2.

The magnitude of the power depends upon the dimensions of the holes. This leakage power at both the holes are in phase at hole 2, adding up the power contributing to the forward power P f. However, it is out of phase at hole 1, cancelling each other and preventing the back power to occur. As a waveguide system cannot be built in a single piece always, sometimes it is necessary to join different waveguides.



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