- #Reflection coefficient smith chart how to
- #Reflection coefficient smith chart series
A fractured end surface gives better results than does a polished end surface. Accuracy is strongly affected by the flatness of the end surface. The refractive index profile is obtained from the reflection coefficient profile by shifting the reference point. A laser light beam with a small spot size is focused into the end surface of a sample, and the reflection coefficient is measured by comparing the incident and reflected light intensity, as shown in Table III. The refractive index profile of an optical fiber can be measured by utilizing this principle. The reflection coefficient of a dielectric material is related to the refractive index at the incident surface.
Impedance Matching by Using Smith Chart – A Step-by-Step Guide, Part II.Kenichi Iga, in Encyclopedia of Physical Science and Technology (Third Edition), 2003 VI.C Reflection Pattern. ← Impedance Matching-Using Lump Elements, Formulas, and Conversions-Part II. Visit ABOUT to see what you can learn from this blog.’ ‘Note: This is an article written by an RF engineer who has worked in this field for over 40 years. We’ll continue to discuss Type #3 and Type #4 impedance matching in the next article. Question: Match this Type #2 impedance \(z=0.5+j0.3\) using Smith chart. 11 Type #2 impedance matching, Step 1 & Step 2Īnd the admittance values of added elements are: We then follow the 2nd rule and move both points O1-S1 & O2-S1 along the \(g=1\) circle to the origin \(z=1\) by simply adding an inductor, Option #1, or a capacitor, Option #2, in shunt respectively.įig. We can fairly accurately read the locations of both points in the Smith chart: #Reflection coefficient smith chart series
The only options to satisfy this first rule is add a capacitor, Option #1, or an inductor, Option #2, in series to move the impedance \(z\) along the \(r=0.4\) circle until meeting \(g=1\) circle at points O1-S1 & O2-S1.įig. 8, we can simultaneously read the impedance \(z\) and admittance \(y\) of point X:įollow the first basic rule of impedance matching, add a lossless element, capacitor or inductor, to get the real part of either impedance or admittance to be 1. 8 Type #2 impedance in the Smith chartĪs showed in Fig. Locate the impedance \(z=r+jx\) in the Smith chart, point X.įig. If the impedance is \(Z=R+jX\), then the normalized impedance is \(z=Z/50=r+jx\).ģ.
#Reflection coefficient smith chart how to
If return loss \(S_\) or reflection coefficient \(Γ\) is given by datasheets, then refer to this article Smith Charts-Basics, Parameters, Equations, and Plots to learn how to convert the number to impedance.Ģ. The process to match a Type #1 impedance into 50Ω:ġ. Type #1 impedance is located within the area of \(r=1\) circle. Matching Type #1 impedance: r ≥ 1, x any value.
Add the second lossless element to tune out the remaining imaginary part, reactance or susceptance, so the resultant impedance or admittance is a real number 1 (\(z=1+j0\) or \(y=1+j0\)). Add a lossless element, capacitor or inductor, to get the real part of either impedance or admittance to be 1. The very basic RULES of impedance matching are: However, I would not suggest to use lumped elements for impedance matching over 5 GHz because it’s hard to find small enough elements, value and size, and the path length will play a main role for the matching process. Theoretically all these 4 types of impedance can be perfectly matched into 50Ω by using only 2 lumped elements, inductors and capacitors, if not considering the limited amount of component values we are able to get as well as their tolerances. 1 Four types of impedance in the Smith chart. Only after finishing reading the sequence and knowing all basics, you then can use this skill effectively.īased on the values of r, g, x, and b, we can roughly categorize the impedance into 4 different types:įig. However, if you are vague to the Smith chart then you should STOP here and go back to learn the Smith Chart Basics first. The only thing you need to do is enter S11 or to-be-matched impe dance and you’ll get the approximate result by following all steps. In this article you’ll learn the step-by-step guide to match Type #1 and Type #2 impedance by simply using Smith chart without knowing those formulas. Impedance Matching-Using Lump Elements, Formulas, and Conversions-Part II. Impedance Matching-Using Lump Elements, Formulas, and Conversions-Part I. We have learned the impedance matching for all 4 Types of impedance using formulas & their conversions, and it’s recommended to visit these 2 articles before you continue to read further here:
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