Contents
What is a stub Smith chart?
Overview of stub tuning examples using the Smith chart to match RF lines to various loads. This occurs by placing a specific length of stub a specific distance away from the load.
Why is single stub matching inaccurate on coaxial line?
For a coaxial line, it is not possible to determine the location of a voltage minimum without a slotted line section, so that the placement of a stub is extremely difficult at the required point. Hence the single stub matching is inaccurate on a coaxial line.
Which stub is mostly preferred?
Explanation: For co-axial cables and waveguides, short-circuited stub is usually preferred because the cross-sectional area of such an open-circuited line may be large enough to radiate, in which case the stub is no longer purely reactive.
How to calculate single stub matching using Smith chart?
The solution is also done u… This video demonstrates the calculation of location and length of single stub for achieving impedance matching using smith chart. The solution is also done u…
How to get the values for a short circuit stub?
If we want to get the values for a short circuit stub, we have already done all the work on the smith chart; we just need to read it from the open circuit side. Doing so you should simply get L1 = 0.128λ and L2 = 0.373λ. In this example we will be matching a 75Ω line to a load that has an impedance of 90+j60Ω.
How to calculate the impedance of a single stub?
To do this, we need to choose so that the real part of the input admittance is equal to the characteristicadmittance, and then choosedso that the reactive components cancel. This can all be done on the smith chart. Single-Stub Matching Example
Where to place a shunt stub on a Smith chart?
Shunt stubs are by far the most common arrangement, so we will look at these first. Like the name implies, a shunt stub of some unknown length will be placed in parallel with the transmission line at some point near the load, the parameters of which we will generate using a Smith chart.