It uses a calculator interface to create mathematical formulas as shown in the fig.4. Selector label and configure the value(s) handled by each case.įig 3 LabVIEW screen shot of case structure Use the labeling tool to enter value(s) in the case Right-click the structure border to add or delete cases. The value wired to the selector terminal determines whichĬase to execute and can be Boolean, string, integer, or enumerated type. Have one or more sub diagrams, or cases, exactly one of which executes when the structure executes as shown in fig.3. Following system tools of LabVIEW are being utilized in The normalized input admittance at terminals BB' is Ĭosl-b2sinl (g' +jb' )+jĪ. Then the equation for the normalized admittance at terminalįrom the above equation the final lengths of both the stubs can be written as ĪBCD matrices for a shunt stub having a normalized input susceptance b and for a section 1 of a lossless transmission line are respectivelyĪBCD matrix for the combination of transmission line of length L and the shunt stubs at ports AA and BB.Ĭ D j cosl-b2sinl 6 and 7 value of b1 and b2 can be calculated. Representation, because they can be used easily in cascade connection.įrom eq. L l= distance between first stub and loadĪBCD parameters can be used for transmission line network LB = length of second stub L=distance between the stubs With the use of the ABCD-matrix (the chain- parameter) representation for a transmission-line network an analytical solution for the general double-stub impedance-matching problem can be obtained.įrom the fig, 2 load admittance YL is to be matched to a main line with characteristics admittance YO. Parameters such as lengths of two stubs and minimum length required between first stub and load can be computed by known parameters. Once the load impedance and the distance between two stubs are known all the parameters of the double stub matching can be determined. įig.1 shows the entire procedure of the system. Once the load impedance and frequency is taken into consideration with the use of it all the parameters of the double stub matching can be determined. In our case study the distance between load and first stub is not zero. The minimum value of this distance is not easily found on a Smith chart, nor is analytical formulas available for the determination of this minimum distance. In that case, a distance must be allowed between the first stub and the load. It involves four parameters namely, the lengths of the two stubs ,distance between two stubs, and the distance between first stub and the load. The techniques for solving impedance matching problems on a smith chart are well known. In the double stub position of the stub can be fixed on transmission line, so no need to change the position of stub. Double stub matching can resolve this problem of single stub matching. In the single stub matching stub length and position of the stub on transmission line need to be changed as load impedance changes, in practice it is difficult to implement. But double stub matching using LabVIEW is better method for impedance matching. There are many methods for impedance matching like quarter wave transform, single stub matching and double matching etc. Keywords Impedance Matching, Double Stub, LabVIEW Program With the use of LabVIEW program, parameters of this technique can be easily found. Solving double stub matching problem on Smith Chart is very manual and time consuming. Scope of impedance matching using single stub is restricted when load impedance or frequency is varying, double stub matching can be used for varying load and frequency. Impedance matching is very essential for transferring maximum power from source to load. Gandhi2, Rajsingpġ Department of Electronics and communication, PIT, Limda, Vadodara 2 Department of Instrumentation and control, DDU, Nadiadģ Institute for Plasma Research, Bhat, GandhinagarĪbstract – This paper introduces useful concept of impedance matching with double stub technique using graphical programming language – LabVIEW. Simulation of Double Stub Impedance Matching using LabVIEW
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