Electromagnetics(ENGR 367)课件.ppt

精品文档 Types of T-lines and Their Applications 精品文档 Outline of Lecture Identify Types of T-lines versus Waveguides Detail construction and applications of each type Provide formulas for T-line parameters of each type that depend on LF or HF operation Lossy or Lossless conditions Show examples of T-line parameter calculation Draw some conclusions 精品文档 Types of T-lines Coaxial cable Two-wire line Stripline and Microstrip Line Other specialized variations 精品文档 T-lines versus Waveguides T-lines operate in the TEM mode only (Transverse ElectroMagnetic waves) Waveguides carry EM waves that May propagate in the TM or TE modes at higher frequencies and may perform more efficiently than T-lines in the microwave range Take a zig-zag path as they reflect off the conducting boundaries and propagate along the main axis of the waveguide 精品文档 Detailed Description of IndividualT-line Types and Their Applications Coaxial Cable: Basic Construction Radio-grade flexible RG-59 (Z0 = 75 ?) coaxial cable. A: outer plastic sheathB: copper screenC: inner dielectric insulatorD: copper core Other standard types have similar construction. from /wiki/Coax 精品文档 Coaxial Cable Other aspects of basic construction Stiffness options available on the market Flexible type: has braided sheath Rigid type: has a solid sheath (Sheath in either case typically made of Cu) Dielectric insulating layer Thickness and permittivity determine Characteristic Impedance (Z0) Attenuation (?) May be either solid or perforated 精品文档 Applications of Coaxial Cable Short runs to connect Home video equipment Ham radio setups (transciever ?? antenna) Satellite TV (dish Rx ? set) Cable modem VSAT for Internet Access Broadcast radio communication (Tx ? ant.) 精品文档 Applications of Coaxial Cable Long runs to connect Formerly radio and TV networks (Now replaced by optical and satellite networks) Presently cable TV signals 精品文档 Specialized Variations of Coax Triaxial Cable (triax): includes a 3rd layer of shielding,