 Hello friends, I am talking on SMIC chart which is part one in which I will be talking on SMIC chart basics, Myself Rohini Mergo working in ANTC department as associate professor at Walshian Institute of Technology, Sulapur. Learning outcomes at the end of this video you will be able to explain the elements of SMIC chart, you will be able to locate short circuit, open circuit point and center of the chart, you will be able to locate the angle of reflection coefficient and transmission coefficient circle, you will be able to locate the wavelength towards load or generator circle, you will be able to list the applications of SMIC chart, these are the contents of my video in which first I will give the introduction, I will explain the elements of the SMIC chart, then I will talk about the angle of reflection coefficient and transmission coefficient circle, then wavelength towards load generator circle, short circuit and open circuit and center of the chart, then normalized impedance and the applications. Introduction Originally, SMIC chart was developed around 1940 by Phyllis Smith, so the name is named as SMIC chart, SMIC chart is fantastic tool for visualizing the impedance of a transmission line and antenna sustain as a function of frequency, SMIC charts are also extremely helpful for impedance matching purposes. It is a useful tool for making the equations involved in transmission lines easier to manipulate, different parameters we can manipulate using SMIC chart. What is an impedance? Impedance Electrical impedance is the major of opposition that a circuit presents to occur and when voltage is applied. The term is named as a complex impedance and may be used interchangeably as impedance. Impedance can be represented in rectangular form, why it is named as a complex that you understand here, z is equal to r plus jx where z is the impedance, r is its resistance and x is reactance, this is a rectangular form of representation. Impedance can also be represented in polar form as z is equal to modulus of z and angle theta where modulus of z is magnitude of impedance, theta is the phase difference between voltage and current. Elements of SMIC chart Two major elements which are two circles or arcs, those are named as the constant r circles which are called rn circles, the constant x circles which are called xn circles. These are the elements of SMIC chart. Let us look first for rn circles. The set of circles referred to as a constant resistance lines form circles. What I mean is, along this axis if you see all the circles are drawn with respect to this real axis, these are constant r circles or rn circles, r is equal to 2, r is equal to 1.5 and 0 it goes on reducing the value of r and at this point r is infinite, all tangent to each other at the right hand of the horizontal diameter. Resistance is held constant while the reactance is varying. Along the circles resistance is constant, reactance is varying. These are called as rn circles. Xn circles, if you see these xn circles, these xn circles are no longer the circles but these are arcs. The constant x circles are more of arcs than circles. This is x is equal to 1, x is equal to 2, x is equal to 0.5 and 0. In the lower half, the xn values are negative minus 0.5, minus 1, minus 2 and so on. So all tangent to each other right hand extreme of the horizontal diameter, they are generated when the impedance has a fixed reactance but a varying value of resistance. These xn circles are generated when the impedance has a fixed reactance but varying value of resistance. So when I superimpose this rn circle, which rn circle, can you see this? This is the rn circle and this is the xn circles. When I superimpose these two circles on each other, I will get the chart like this. These are circular or the rn circle, the arcs are the xn circles. Those superimposed on each other will form the smith chart, rn and xn circles superimpose. Whether the actual smith chart is like this? No. This is a simplified form of a smith chart. Actual smith chart looks like this. It is much more complex than whatever shown here. But the same information is available on this chart also. All these circles are the rn circles, all these circles are the rn circles whereas the rn values are shown on this horizontal axis with rn value maximum on this side which is infinite and then 50 and so on and then goes on decreasing, then 1 and so on and 0.5, 0.1 and 0 on this side. So this is the rn circles and these are the xn circles. You can see these are the xn circles and the xn value on the horizontal axis is 0. On the upper side of the circle, the xn values are positive. On the lower half of the circle, the xn values considered are negative. Always hold the smith chart with this open circuit side on your right hand side and short circuit side towards your left hand side. What is this open circuit and short circuit point that I will talk further? Smith chart has one more variant. The same chart can also be represented like this with the same open circuit point, short circuit point and all these xn rn circles are there. But there is one more lower chart shown. This chart indicates the different parameters which can be measured either by using this smith chart by locating the point and then locating the point on this chart or the other method is directly by using this chart also we can determine the different values or the parameters. Angle of reflection and transmission coefficient circle. The circle immediate to rn circle is the angle of reflection coefficient circle. It ranges from 0 to 180 degree. The angle of reflection coefficient ranges from 0 to 180 degrees on upper half of the circle and lower half of the circle has negative values of the angles. This is because impedance repeats for every half wavelength. So here the angle of reflection coefficient circle I have shown. The same smith chart this part is zoomed and I have shown here. So here you can see here this is the rn0 circle and immediate to that after that there is one more circle which is named as angle of reflection coefficient circle. So you can see here this is the angle of reflection coefficient circle and if you read the values the values here will be changing from 0 to 180 degrees around this circle. Beyond that there is a lower scale. On the scale also there are different parameters shown and this scale also shows the angle of reflection coefficient and angle of transmission coefficient values. Wavelength towards load or wavelength towards generator. So after this the outermost circle marked wavelength towards load or wavelength towards generator what I mean by that is this is a generator and having some source impedance and terminated in some load impedance ZL and if I move somewhere here in between what is the impedance here if I want to find. So this is a wavelength towards generator if I move from load. If I move from source it is wavelength towards load. So at this point what is the condition of the transmission line if I move from load at this point. What is the condition of transmission line? What is its impedance? What is its whether there is a voltage minimum maximum? What is the impedance value? All this we can find out by using this circle wavelength towards generator or load circle by moving along it along the circle. Let us see the where this circle is there. So here I have zoomed out this part it looks like this. If you read here after angle of reflection coefficient circle there is one more circle which is marking zone from inside as well as outside and this is wavelength towards generator and wavelength towards load both are shown in different directions opposite directions there are the markings shown in terms of wavelength lambda. Let us locate a short circuit open circuit and center of the chart. This is the Smith chart as I already said the impedance or the resistance here is infinite. So Rn equal to infinite is this point which is point A as Rn is infinite this point of course will be the open circuit point. As the Rn values I look at this real axis goes on reducing reducing here 0.1 and at this point it is 0. As here Rn value is 0 this is a short circuit point with Rn equal to 0. Now what is the center of the chart between these two there is a center of the chart point O where Xn value of course is 0 but Rn value is 1. So that is nothing but center of the chart. The chart is normalized Zn all impedances on the chart are normalized with respect to characteristic impedance Z0. Normalized impedance Zn can be given as Zn is equal to Z upon Z0 the given impedance upon Z0 R upon Z0 plus J upon J into X upon Z0. So R by Z0 is the real part and X by Z0 is the imaginary part which we want to locate on the Smith chart. If we try to work with normalized impedances on the Smith chart the reason is very simple because when we locate the impedance on the Smith chart I can locate 1 ohm, I can look at 50 ohm, I can look at 500 ohm, I can look at 5000 ohm and more than that. So when the impedance values is increasing whether it is expected that the chart should expand and when impedance values are reducing in order to increase the accuracy whether the chart should compress or expand so all this is not possible. So for that a single chart is there which works with all the impedances provision is made to locate a point of the impedance with respect to characteristic impedance Z0 which is called as normalized impedance. List the applications so if there are different applications of the Smith chart basically the application the first application of the Smith chart is the impedance matching. Why we need impedance matching because when I connect the load the load should be matched with respect to source but practically every time it is not possible that the load is matched but in order to match the load how we can work out we can connect a stub single stub matching double stub matching methods are there. So using that we can match the load with respect to source. Why impedance matching is required in order to get the highest efficiency in order to get whatever you are transmitting the maximum should be received towards the load side for that the impedance matching is expected. So basically the application of Smith chart is for impedance matching purpose beyond that we can determine the different parameters using the Smith chart such as admittance, impedance at any point on the transmission line, we can determine the reflection coefficient, we can determine the VSWR, even we can determine the maximum voltage and the minimum voltage positions on the transmission line where the Vman and Vmax is located that also we can do and also we can determine the maximum load or maximum impedance along the transmission line and the minimum impedance along the transmission line. These are the references used for preparing this video. Thank you.