Microstrip Surface Microstrip Consists of a signal line, the top and sides exposed to air, on the surface of a board of dielectric constant E r and referenced to a power or ground plane. Surface microstrip can be implemented by etching one surface of double- sided PCB material.

Microstrip Embedded Microstrip Embedded, or buried, microstrip is similar to the surface microstrip, however the signal line is embedded in a dielectric and located at a known distance H1 from the reference plane.

Microstrip Coated Microstrip Coated microstrip is similar to the surface version, however the signal line is covered by a solder mask. The solder mask coating can lower the impedance by up to a few ohms (depending on the type and thickness of the solder mask).

Microstrip Distributed circuit model of a lossy transmission line.

Microstrip Microstrip Equations

Waveguides A waveguide is a special form of transmission line consisting of a hollow, metal tube. The tube wall provides distributed inductance, while the empty space between the tube walls provide distributed capacitance:

Waveguides Waveguides are practical only for signals of extremely high frequency, where the wavelength approaches the cross-sectional dimensions of the waveguide. Below such frequencies, waveguides are useless as electrical transmission lines.

Waveguides Only one of the fields -- either electric or magnetic -- will actually be transverse to the wave's direction of travel, the other loops Longitudinally.

Waveguides Field remains transverse to the direction of travel determines whether the wave propagates in TE mode (Transverse Electric) or TM (Transverse Magnetic) mode

Waveguides Signals are typically introduced to and extracted from waveguides by means of small antenna-like coupling devices inserted into the waveguide.

Problems:- Ex 3-1: A uniform transmission line has Constant R= 12m  m -1; G=1.4  Mhom -1; L =1.5  Hm -1; C = 1.4  Fm -1 at Frequency of 7kHz Find a) Characteristic Impedance b) Attenuation in decibels per km

Solution Ex 3-1: Z 0 = {(R+j  L)/(G+j  C)} 1/2 ={10 -3 x 67  80 0 }/{10 -6 x 62  } 1/2 = 33 – j2.5  ………. (a)  = Re{(R +j  L)(G+j  C)} 1/2  = 1.82 dB/km

Problem Ex3-2: Find the Impedance of the line m? V line = N s V cell =  N,Eh I line = N p I cell =  N p Hw Solution:- N s = 4 and N p = 7 Z line = V line /I line = (N s /N p). Z 0 Therefore Z line = (4/7) 377 h w