![]() ![]() In many cases, you need to measure and carefully simulate the appropriate impedance required to ensure impedance matching and prevent power reflection. High speed and high frequency systems need impedance matching to ensure efficient power transfer and prevent reflections. Impedance matching in this PCB can be determined using a Smith chart Once impedance matching requirements are determined, the results can be simulated in a SPICE-based simulation application. One popular method for plotting impedance and determining impedance matching is to use a Smith chart. This is called double-stub matching and allows for the adjustment of the load impedance.There are many methods for impedance matching in your circuits. Instead of having a single stub shunted across the line, we may have two stubs. Since we have two possible shunted stubs, we normally choose to match the shorter stub or one at a position closer to the load. Thus we obtain d = d A and d = d B, corresponding to A and B, respectively, as shown in Figure 11.20. Similarly, we obtain d = d B as the distance from Psc to B' (ys = jb). For the stub at A, we obtain d = dA as the distance from P to A', where A' corresponds to ys = -jb located on the periphery of the chart as in Figure 11.20. At A, ys = -jb, l= l A and at B, ys = jb, l = l B as in Figure 11.20.ĭue to the fact that the stub is shorted (y' L =∞), we determine the length d of the stub by finding the distance from Psc (at which z'L = 0 j0) to the required stub admittance ys. Since b could be positive or negative, two possible values of l (<λ/2) can be found on the line. If a shunt stub of admittance y s = -jb is introduced at A, thenĪs desired. Consequently, shunt short-circuited parallel stubs are preferred.Īs we intend that Z in = Z o, that is, z in = 1 or y in = 1 at point A on the line, we first draw the locus y = 1 jb(r = 1 circle) on the Smith chart as shown in Figure 11.20. It is more difficult to use a series stub although it is theoretically feasible.Īn open-circuited stub radiates some energy at high frequencies. Notice that the stub has the same characteristic impedance as the main line. The tuner consists of an open or shorted section of transmission line of length d connected in parallel with the main line at some distance from the load as in Figure 11.19. The major drawback of using a quarter-wave transformer as a line-matching device is eliminated by using a single-stub tuner. Shorted stubs are usually preferred because opened stubs may radiate from their opened ends. In coaxial cable or two-wire line applications, the stubs are obtained by cutting appropriate lengths of the main line. They consist of shorted or opened segments of the line, connected in parallel or in series with the line at a appropriate distances from the load. Stub matches are widely used to match any complex load to a transmission line. Reflection of a Plane wave at oblique incidence.Reflection of a plain wave in a normal incidence.Link between electric and magnetic fields.Waves and applications and Electromagnetic wave propagation.Forces due to magnetic field-Between Two Current Elements.Forces due to magnetic field-Current Element.Forces due to magnetic field-moving charged particle.Infinitely Long Coaxial Transmission Line-Ampere's Law.Magnetostatics and Magnetic forcesmaterials and devices.A Line Charge above a Grounded Conducting Plane.A Point Charge Above a Grounded Conducting Plane.General procedures for solving Poission’s or Laplace’s equations.Conductor-Free Space Boundary Conditions.Conductor-Dielectric Boundary Conditions. ![]() Dielectric-Dielectric Boundary Conditions.Relationship between E and V-maxwell's Equation.Electric field due to charge distribution.Electrostatics and Electric field in material space.Differential Lengths in Spherical Coordinates.Differential length in Cylindrical Coordinates.Differential Lengths in Cartesian Coordinates.Spherical to Rectangular Coordinate Transformation.Rectangular to Spherical Coordinate Transformation.Cylindrical to Rectangular Coordinate Transformation.Rectangular to Cylindrical Coordinate Transformation.Coordinate systems and transformation and Vector calculus. ![]()
0 Comments
Leave a Reply. |