1. Transmission Line Theory
Prepared By: Guided By:
Bhaggyashree Deshmukh( ) Trupti Engineer.
Mansi Patel( )
Dipanjali( )

2. INTRODUCTON
In an electronic system the delivery of power requires the connection of two wires between the source and the load.
At low frequency region power is considered to be in electric and magnetic fields that are guided from lace to place by some physical structure.
Any physical structure that will guide an electromagnetic wave place to place is called transmission line.

3. Types Of Transmission Lines
Two wire line
Coaxial cable
Waveguide
- Rectangular waveguide
- Circular
Planar transmission lines.

4. Coaxial cable

5. Analysis of difference between low and high frequency
At low frequencies the circuit elements are lumped since voltage and current waves affect the entire circuit at the same time.
At the microwave frequencies such treatment of circuit elements is not possible since voltage and current waves do not affect the entire circuit at the same time.
This is because the dimensions of the circuit are comparable to wavelengths.
I=c/f

6. Transmission Line Concept
The transmission lines are divided into small units where the circuit elements can be lumped.
Assuming the resistance lines is zero then the transmission line can be modeled as an LC ladder network with inductors in series arms and capacitors in shunt arms.
Velocity of the wave is equal to
V(m/s)=1/T

7. Reflection from Resistive loads
When the resistive load termination is not equal to the characteristic impedance part of the power is reflected back and remainder is absorbed by the load.
The amount of voltage reflected back is called voltage reflection coefficient
G=Vr/Vi
Where Vr=incident light
Vi=reflected light

8. General Input Impedance Equation
Input impedance of a transmission line at a distance angle from load impedance ZL with a characteristic Zo is
Z input = Zo [(ZL + jZo BL)/(Zo + j ZL BL)]
Where B is called phase constant or wavelength constant.

9. Coaxial Components
Connectors: Microwave coaxial connectors are required to connect two coaxial lines are also called connector pairs.
Coaxial section: Coaxial line sections slip inside each other while still making electrical contact.
Attenuators: The function of attenuator is to reduce the power of signal through it by fixed or adjustable amount.

10. Waveguide Components
The waveguide components generally encountered are
Directional couplers
Tee junction
Attenuators
Impedance changing devices
Isolator switches
Cavities
Filters
Detectors

11. Tees
Hybrid Tee junction: Tee junctions are used to split waves from one waveguide to two other waveguide.
Hybrid Tee junction: The E-plane and H-plane Tees can be combined to form a hybrid tee.

12. Attenuator

13. Attenuators
Attenuators are the components that reduce the power a fixed amount or variable amount or in series of fixed steps from input to output device.
Slide wave attenuator, Flap attenuator, Rotary vane attenuator are the types of attenuator.

14. Thank You!