This document provides an overview of basic electronics topics including transmission lines, waveguides, and antenna fundamentals. It discusses the characteristics and applications of transmission lines, advantages of using them to reduce electromagnetic interference, and examples of different types of transmission lines. Waveguides are introduced as an alternative to transmission lines at higher frequencies. Key concepts around waveguides such as applications and the expression for cutoff wavelength are summarized. Finally, the document outlines fundamental concepts relating to antennas such as radiation patterns, efficiency, and gain.

1. Basic Electronics
Prepareed By:
● Patel Yash K. - 130420109537
● Pawar Kumar S. - 130420109538
● Rathod Kishan . -130420109539

2. Topics
● Transmission Lines
● Waveguides
● Antenna Fundamentals

3. Characteristics of and
applications of
Transmission lines
● Advantages:
– Less distortion, radiation (EMI), cross-talk
● Disadvantage
– More power required.
● Applications, transmission lines can
handle
– Signals traveling in long distance in
Printed-circuit-board PCB
– Signals in a cables, connectors (USB,
PCI).

4. Advantage of using
transmission lines:
Reduce Electromagnetic
Interference (EMI) in
point-to-point wiring
● Wire-wrap connections create EMI.
● Transmission lines reduce EMI
because,
– Current loop area is small, also it
constraints the return current (in ground
plane) closer to the outgoing signal path,
magnetic current cancel each other.

5. Different
transmission lines
1. Coaxial (unbalanced) line and
2. Parallel-wire (balanced) line

6. Coaxial Cables

7. Coaxial Cable Labels

8. ● R=resistance; G=conductance;
C=capacitance; L=inductance. All unit length
values.
Dv
R dx L dx
v
dx

9. Important result for a
good copper
transmission line and w
=constant
● Z0= [(R+j w L)/(G+j w C)]=characteristic
impedance
● If you have a good copper
transmission line R,G are small, and
● if the signal has a Constant frequency w
● therefore
● Z0=(L/C)1/2= a constant

10. Waveguides
Introduction
At frequencies higher than 3 GHz, transmission
of electromagnetic energy along the
transmission lines and cables becomes difficult.
This is due to the losses that occur both in the
solid dielectric needed to support the conductor
and in the conductors themselves.
A metallic tube can be used to transmit
electromagnetic wave at the above frequencies

11. Definition
A Hollow metallic tube
of uniform cross
section for
transmitting
electromagnetic
waves by successive
reflections from the
inner walls of the tube
is called waveguide.

12. Applications of circular
waveguide
 Rotating joints in radars to connect the horn
antenna feeding a parabolic reflector (which
must rotate for tracking)
 TE01 mode suitable for long distance waveguide
transmission above 10 GHz.
 Short and medium distance broad band
communication (could replace / share coaxial
and microwave links)

13. Wave Guide Medium

14. Expression for cut off
wavelength
For a standard rectangular waveguide, the cutoff
wavelength is given by,

2
2 2
n
ö çè
÷ø
m
ö çè
æ + ÷ø
æ
=
b
a
c l
Where a and b are measured in centimeters

15. Advantages
● Small size
● Reduced losses ascompared to a
transmission line
● Operation at very high frequency is possible
(upto 325 Ghz)
● They are simpler to manufacture.
● Large power handling capacity.

16. Disadvantages
● Low Frequency operation is not possible as
they become bulky at low frequency.
● Absolute efficiency is low.

17. Antennas
● Function of antennas
● Radiation Pattern of antenna
● Isotropic Radiator
● Efficiency
● Gain

18. Antennas
Transmitting Antenna: Any structure designed to
efficiently radiate electromagnetic radiation in a
preferred direction is called a transmitting antenna.
Wires passing an alternating current emit, or
radiate, electromagnetic energy. The shape and
size of the current carrying structure determines
how much energy is radiated as well as the
direction of radiation.
Receiving Antenna: Any structure designed to
efficiently receive electromagnetic radiation is called
a transmitting antenna
We also know that an electromagnetic field will induce
current in a wire. The shape and size of the structure
determines how efficiently the field is converted into
current, or put another way, determines how well the
radiation is captured. The shape and size also determines
from which direction the radiation is preferentially
captured.

19. Antennas – Radiation Patterns
Radiation patterns usually indicate either electric field intensity or power
intensity. Magnetic field intensity has the same radiation pattern as the
electric field intensity, related by ho
It is customary to divide the field or power component by its
maximum value and to plot a normalized function
Normalized radiation intensity:
( ) ( , ,
)
max
n ,
P r
P
P
q f
q f =
Isotropic antenna: The antenna radiates
electromagnetic waves equally in all directions.
( , ) 1 n iso P q f =

20. Antennas – Radiation Patterns
Radiation patterns usually indicate either electric field intensity or power
intensity. Magnetic field intensity has the same radiation pattern as the
electric field intensity, related by ho
It is customary to divide the field or power component by its
maximum value and to plot a normalized function
Normalized radiation intensity:
( ) ( , ,
)
max
n ,
P r
P
P
q f
q f =
Isotropic antenna: The antenna radiates
electromagnetic waves equally in all directions.
( , ) 1 n iso P q f =

21. Antennas – Radiation Patterns
Radiation Pattern:
A directional antenna radiates and receives
preferentially in some direction.
A polar plot
A rectangular plot
It is customary, then, to take slices of the
pattern and generate two-dimensional
plots.
The polar plot can also be in terms of decibels.
( ) ( , ,
)
max
, n
E r
E
E
q f
q f =
( , ) ( ) 20log[ ( , ) ] n n E q f dB = E q f
It is interesting to note that a normalized
electric field pattern in dB will be identical to the
power pattern in dB.
( , ) ( ) 10log[ ( , ) ] n n P q f dB = P q f

22. Antennas – Radiation Patterns
A polar plot
A rectangular plot
Radiation Pattern:
It is clear in Figure that in some very
specific directions there are zeros, or nulls,
in the pattern indicating no radiation.
The protuberances between the nulls are
referred to as lobes, and the main, or
major, lobe is in the direction of maximum
radiation.
There are also side lobes and back lobes.
These other lobes divert power away from
the main beam and are desired as small
as possible.
Beam Width:
One measure of a beam’s directional nature is
the beamwidth, also called the half-power
beamwidth or 3-dB beamwidth.

23. Antennas – Efficiency
Efficiency
Power is fed to an antenna through a T-Line and
the antenna appears as a complex impedance
Zant = Rant + jXant .
where the antenna resistance consists of
radiation resistance and and a dissipative
resistance.
ant rad dis R = R + R
For the antenna is driven by phasor current j
The power radiated by the antenna is The power dissipated by ohmic losses is
2 1
2 rad o rad P = I R 2 1
2 diss o diss P = I R
An antenna efficiency e can be defined as the ratio of the radiated
power to the total power fed to the antenna.
P R
= =
rad rad
rad diss rad diss
e
P + P R +
R
o s I = I e a

24. Antennas – Gain
Gain
The power gain, G, of an antenna is very much like its directive gain, but
also takes into account efficiency
G(q ,f ) = eD(q ,f )
The maximum power gain
Gmax = eDmax
The maximum power gain is often expressed in dB.
( ) ( ) max 10 max G dB = 10 log G

25. Types of Antennas
1. Dipole antennas
2. Horn antennas
3. Parabolic antennas
4. Yagi antennas