- Single stub and double stub matching using smith chart pdf generator#
- Single stub and double stub matching using smith chart pdf series#
Distance (P to B) or (P to D) will give us what the reactive part should be at that location since we know already the conductive part is equal to 1. When this circle intersect g = 1 circle, at that point it means the real part will be equal to the characteristic impedance Z o. We draw the constant VSWR circle passing through P. Let P be the normalized admittance to be matched in figure 1.3. Lets see how this work on the smith chart. Let loadĪnd normalized load admittance with respect to characteristic admitance Doing this analytically is tedious but using smith chart is easier.įor single stub matching, it is better to work in terms of admittances because of the parallel connection. The function of Length L(location of stub), is to make impedance Z to be equal to characteristic impedance(Z o ) and length of stub(L s ) functions to neutralize the reactive part. Choose L s, such that the reactive part of stub cancels the reactive part of the load after its transformation. Therefore, the solution is as follows we need to find the length L L such that when Z is transformed by this distance, the resistive part becomes equal to Z o and the parallel combination of the transformed impedance and the reactive part from the stub cancels out. Since there is no reflection beyond A i.e the input impedance is always going to be equal to the characteristic impedance. If we make sure that both reflected energy from stub and from load match each other in amplitude and are opposite in phase, there will be no reflection beyond node A. At the load, there is reflection and since the stub is sort circuited, there is a total reflection which is in opposite direction (Γ s.c = −1).
Single stub and double stub matching using smith chart pdf generator#
We know that as voltage or energy moves from generator to the load, it sees two(2) parts: the stub section and load Z section. The stub length L s is connected in parallel to the main transmission line at a distance L L from the impedance to be matched. We connect the auxiliary transmission line to the main transmission line. The main line with characteristics impedance Z o is connected to impedance Z. Real impedance at point A in figure 1.1 which is equal to Z o. Again, our aim is to find aįigure 1.1: Single stub matching technique with one auxiliary line attached We are going to consider the single stub matching technique in the parallel short circuit type. Triple Stub matching technique -Three appended auxiliary line.Double Stub matching technique -Two appended auxiliary line.Single Stub matching technique -One appended auxiliary line.
There are three (3) techniques for appending an auxiliary line (stub) to the main line. What we want to change now is the length l from load (location of stub) and the length of the auxiliary transmission line attached to the main transmission line (Ls). The characteristic impedance of the main and auxiliary transmission line remains the same. Note : We do not require a unique characteristic impedance (Z o) for each impedance matching. In this article, we are going to be concentrating on the Parallel Short Circuit Stub Matching Technique.īy using the stub at proper location on the main transmission line, it is possible to match a complex impedance(Z) to the characteristic impedance (Z o). There are four(4) types of stub matching technique,
Single stub and double stub matching using smith chart pdf series#
In this article, we are going to learn about Stub Matching Technique.Ī stub is an auxiliary section of a transmission line which is either short circuited (S.C) or open circuited (O.C), appended or connected to the main transmission line either in series or parallel. From my previous article,i have dealt on impedance matching, using smith chart.
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