Transmission Lines Review SY2021-2022 2nd Term PDF

Transmission Lines Review Transmission & Antenna Systems 1. Transmission Line Circuits, Losses and parameters. Matching TL, Smith Chart 2. Radio Wave Propagation, Power Density and Field Strength Calculations 3. Antenna Systems 4. Wave guides, Fiber Optics Transmission Media Guided vs. Unguid...

Transmission Lines Review Transmission & Antenna Systems 1. Transmission Line Circuits, Losses and parameters. Matching TL, Smith Chart 2. Radio Wave Propagation, Power Density and Field Strength Calculations 3. Antenna Systems 4. Wave guides, Fiber Optics Transmission Media Guided vs. Unguided Medium Guided -this refers to transmission media that requires physical media to facilitate communication Unguided Medium -this refers to transmission media that does not use physical media to facilitate Communication like radio wave propagation, microwave comm., sat comm. etc. Transmission Lines -It is a metallic conductor system used to transfer electrical energy from one point to another. -It is designed to deliver RF power from transmitter to the antenna and maximum signal from the antenna to the receiver. Basic Types Transverse Electromagnetic (TEM) TL - such as coaxial lines and microstrip lines which are designed to support a single electromagnetic wave that propagates along the length of the transmission line with electric and magnetic field vectors perpendicular to the direction of propagation. Higher-order TL - It includes radio-frequency waveguides and multimode optical fiber, are designed to guide waves that have relatively complex structure. Length of Transmission Line  Question Calculate the minimum length of a pair of conductors to be considered as a transmission line, if its operating frequency is 800 MHz. a. 12.4 mm b. 37.5 mm c. 10.2 mm d. 28.5 mm Types of Transmission Line Balanced or Differential Transmission Line -made up of two parallel conductors(signal or carry line and return line) spaced from one another by a certain distance. -both conductors carry signal currents which are equal in magnitude but opposite in direction(metallic Advantage: It has very good noise circuit rejection (noisecurrents). immunity). It cancel effect of noise in amplitude due to opposing direction. Disadvantage: Not cost effective due to pair of wires when used in Types of Transmission Line Unbalanced or Single Ended Transmission Line -This is a transmission line, whose conductors have unequal impedances with respect to ground. It usually consist of a conductor that is considered the signal line and another that is grounded, or is ground itself. Advantage: It is cost effective Disadvantage: Noise rejection is not as good as balanced TL Types of Transmission Line Balun This refers to a circuit device used to connect a balanced transmission line to unbalanced load. Types of Transmission Line Parallel-Wire Transmission Line It is composed two conducting wires separated by a dielectric(insulator). Parallel-Wire TL Categories Open-wire It is simply consists of two parallel wires,closely spaced and separated by air. Twin Lead - it is similar to the open wire, except that instead of spacers a solid dielectric is used along the whole length of the wire. Types of Transmission Line Coaxial Cable It is composed of two concentric conductors and is used extensively for high-frequency applications to reduce losses and to isolate transmission paths. This also provides excellent shielding against external interference. Types of Transmission Line Microstrip is a type of transmission line that consists of a conductor fabricated on dielectric substrate with a grounded plane. It is a flat conductor separated from a ground plane by insulating material. Types of Transmission Line Stripline (Flat Metallic Ground Plane) A microwave transmission line constructed of a center conductor suspended between parallel conductive ground planes. Types of Transmission Line Waveguide is a special form of transmission line consisting of a hollow, metal tube. Wave guides conduct microwave energy at lower loss than coaxial cables. Types of Transmission Line Optical Fibers -is used by telecommunications companies to transmit telephone signals, Internet communication and cable television signals. It is used when high bandwidth, long distance, or immunity to electromagnetic interference is required and as light guides, for different applications i.e. imaging tools, lasers, hydrophones for seismic waves, SONAR, and as sensors to measure pressure and temperature. Transmission Line Equivalent Circuit Physical properties like diameter and conductor spacing and electrical properties such as conductivity and relative permittivity (otherwise known as dielectric constant) determine what we call the primary line constants. Primary Line Constants  Primary Line Constants (distributed parameters) Primary Line Constant Parallel Wire Line Coaxial Cable Series Inductance (L) (H/m) Shunt Capacitanc (C) (F/m) Shunt Conductance (G) Dielectric Vacuum Air Teflon Polyethylene Polyvinyl Relative Permittivity / Dielectric Constant Lumped VS Distributed Lumped systems -systems in which electrical properties like R, L, C etc are assumed to be located on a small space of the circuit. These systems are applicable for low frequency application. Distributed systems assume that electrical properties R, L, C etc are distributed across the entire circuit. these systems are applicable to for high frequency application. Question  Secondary Line Constants It determine the transmission characteristics of the transmission line. These can be calculated using the primary line constants. a) Characteristic Impedance b) Propagation Constant Secondary Line Constants   Characteristic Impedance General Equation Lossless Parallel-Wire Line Coaxial Cable Coaxia Characteristic l Cable Impedance RG-8U RG-58 U RG-59 U Velocity 0.66c 0.66c 0.79c Question  Question  Question  Secondary Line Constants  Question  Question  Question  Question What is the characteristic impedance of an open wire line with conductors 4mm in diameter separated by 15mm? a. 241.52 Ω b. 252.41 Ω c. 421.52 Ω d. 452.21 Ω Question  Question When dc flows through a conductor, the movement of electrons through the conductor’s cross section is uniform. The situation is somewhat different when ac is applied. The expanding and collapsing fields about each electron encircle other electrons. This retards the movement of the encircled electrons. Which phenomenon is referred to? a. self-charging b. self-discharging c. self-induction d. self-conduction Note: please also review neets Transverse Electromagnetic (TEM) It refers to a form of radiant energy which is essentially an oscillatory disturbance in free space that is composed of two components, electric field (E) and magnetic field (H) which are perpendicular to each other and to the direction of propagation. Velocity in Transmission Lines  Velocity in Transmission Lines  Velocity in Transmission Lines  Velocity in Transmission Lines  Velocity in Transmission Lines  Delay Lines  Question  Question  Question  Transmission Line Losses  Reflections  Non-Resonant vs. Resonant Transmission Lines   Reflection Coefficient  Return Loss  Return Loss and Mismatch Loss  Question  Standing Wave -it is the interference pattern of two traveling waves (incident and reflected) Standing Wave Ratio -it is a measure of mismatch between load impedance and the characteristic impedance of a transmission line  Power Relationships  Power Relationships  Question  Question   Inductor Capacitor Parallel resonant Series resonant Capacitor Inductor Question  Question  Question  Question  Question  Question  Question  Transmission Line Instruments  Question  Impedance Matching Networks 2. Stub -is essentially a short section of a transmission line open or shorted. - It is used to remove the reactive component of a load with complex impedance and match it to the line. Types of Matching Stub 1. Series Open Stub 2. Series Short Stub 3. Shunt Open Stub 4. Shunt Short Stub Transmission Line Instruments Smith Chart This refers to a special circular graph transmission line calculator named after Philip Smith. Transmission Line Instruments Optical Time Domain Reflectometer This refers to a device used to perform time-domain reflectometry. The TDR is a technique that can be used to locate an impairment in a metallic cable. Question  Transmission Line Instruments Slotted Line It is a short section of air-dielectric coaxial line with a slot in outer conductor through which a capacitively-coupled probe is inserted. It measures the wavelength and SWR of the line. Question  Question  Question  Question  Question  Inductor Capacitor Parallel resonant Series resonant Capacitor Inductor Question A shorted half-wave line at the operating frequency acts like a(n): a. capacitor b. inductor c. Series resonant circuit d. Parallel resonant circuit Question In signal propagation, the data channel provides the physical path between transmitter and receiver. It could either be guided or unguided. Which of the ff. does not belong to the group? a. wireless b. Optical fiber c. Coaxial cable d. Twisted pair Question Which of the following determines the characteristic impedance of a coaxial antenna feed line? a. The diameter of the braid and the length of the line b. The frequency of the signal and the length of the line c. The diameter of the braid and the frequency of the signal d. The ratio of the diameter of the outer conductor to the diameter of the inner conductor End THANK YOU!