Mini Project 2 - Impedance Matching With A Double Stub Tuner
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This document provides instructions for a laboratory experiment on designing a double stub impedance matching network. Students are asked to design a double stub tuner to match a 50 ohm source line to a load with 25 ohm resistance and 33 pF capacitance at 965 MHz. They will use a Smith chart to determine the lengths of the two stubs. Students will then replace the stubs with lumped passive components and compare the impedance matching performance of the two designs at 965 MHz and 500 MHz. Finally, they are to write a laboratory report and prepare a presentation on the experiment.
Mini Project 2 - Impedance Matching With A Double Stub Tuner
- 1. EEEC6430310 Electromagnetic Fields and Waves Faculty of Engineering and Computer Technology Laboratory Manual Lecturer: Ravandran Muttiah BEng (Hons) MSc MIET Year/Semester: Year 2 / Semester 1 Academic Session: 2020/2021 The information in this documentis important and should be noted by all students undertaking the Bachelor of Engineering (Honours) in Electrical and Electronic Engineering Approved by Coordinator: Endorsed By Dean: ------------------------------------------ __________________
- 2. AIMST University Faculty of Engineering and Computer Technology BEng (Hons) in Electrical and Electronic Engineering Electromagnetic Fields and Waves 1 𝑍L Mini Project 2 - Impedance Matching With A Double Stub Tuner Theory In some instances, the distance determined for the single stub tuner may not be convenient for implementation. In those cases, a double stub tuner may be required as shown in figure 1. In designing double stub tuners, the distances 𝑑stub1 and 𝑑stub2 are pre-determined by the designer. A double stub transmission line impedance matching network is composed of two short circuited sections of transmission line, separated by a length of transmission line, placed along the main signal line. The short circuited sections provides an equivalent shunt susceptance. The short circuited sections are attached perpendicular to the main line as shown in figure 1. The construction of the short circuited section is similar to the main line. The load impedance is typically dependent on the frequency of operation. The distance, 𝐿stub1 , can be moved back and forth to get a wide range of susceptance values. The distance 𝐿stub1 and 𝐿stub2 can be found in terms of fractions of wavelength of the signal being transmitted using a Smith chart. The values of the lumped parameter components can be calculated using the susceptances determined from the Smith chart. Figure 1: Double stub short circuit tuner 𝑍o 𝐿stub1 𝐿stub2 𝑑stub1 𝑑stub2
- 3. AIMST University Faculty of Engineering and Computer Technology BEng (Hons) in Electrical and Electronic Engineering Electromagnetic Fields and Waves 2 Objectives The objective of this experiment is to become acquainted with double stub impedance matching. Demonstrate your ability to design and construct the double stub tuner and to view the function of the matching stub. The stub tuner transmission line impedance matching networks are designed given load components at specified frequencies. Specification Design a Double Stub Tuner Design a 50 Ω microstripline double stub transmission line impedance matching network to match a 50 Ω source and line to a load with a resistance 𝑅 = 25 Ω in series with a capacitance, 𝐶 = 33 pF. Let the distance between the load to the stub closest to stub be 𝑑stub1 = 0.250 λ and the short circuit stub length closest to the load be 𝐿stub1 = 0.204 λ. The relative permittivity of the G-10 printed circuit board is 𝜀r = 4.5. Metal thicknesses of 1.37 mm are typically for 1 oz copper plating. Use a Smith chart to design the matching network at 965 MHz. Verify the matching network at 965 MHz using Agilent ADS software package. How reasobale will the match be at 500 MHz ? Plot 𝑆11 in both rectangular and Smith chart formats as well as the Standing Wave Ratio (SWR). Replace the Stubs With Lumped Parameter Passive Components Re-design the matching network by replacing the stubs with lumped parameter passive components (i.e. inductor and capacitor). Measure the Impedance Matched Networked Verify the re-designed network at 965 MHz using the Agilent ADS software package. How reasonable will the match be at 500 MHz ? Plot 𝑆11 in both rectangular and Smith chart formats as well as the SWR. Compare the results of double stub of microstripline and passive components. Report Write a laboratory report on this project. (1) Explain in detail about the theory of double stub tuner for the designed impedance matching circuit with the theoretical calculations of component values. (2) Discuss the method of productions and fabrications of double stub tuners, and comment on the test results. (3) Prepare slides for presentation and demonstration of this project.