1. FACULTY DEVELOPMENT PROGRAMME on EC6602 - ANTENNA AND WAVE PROPAGATION
VALLIAMMAI ENGINEERING COLLEGE
SRM Nagar, Kattankulathur
DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING
FACULTY DEVELOPMENT PROGRAMME on EC ANTENNA AND WAVE PROPAGATION
UNIT – I
FUNDAMENTALS OF RADIATION
Presented By
S. RAMESH
Reference : Constantine.A.Balanis “Antenna Theory Analysis and Design”, Wiley Student Edition, 2006.

2. Matching – Baluns, Polarization mismatch, Antenna noise temperature.
PRESENTATION OUTLINE
INTRODUCTION
Definition of antenna parameters : Gain, Directivity, Effective aperture, Radiation Resistance, Band width, Beam width, Efficiency,Input Impedance.
Matching – Baluns, Polarization mismatch, Antenna noise temperature.
Radiation from oscillating dipole, Half wave dipole. Folded dipole, Yagi array.
CONCLUSIONS
References
FDP-EC6602-AWP-Unit I-Antenna Parameters

3. To give insight of the radiation phenomena.
OBJECTIVES
To give insight of the radiation phenomena.
To give a thorough understanding of the radiation characteristics of different types of antennas.
To create awareness about the different types of propagation of radio waves at different frequencies.
FDP-EC6602-AWP-Unit I-Antenna Parameters

4. INTRODUCTION
In the 1890s, few antennas in the world & primarily a part of experiments that demonstrated transmission of EM waves.
By World War II, antennas are ubiquitous & usage had transformed the lives of the person via radio and television reception.
Early 21st century, thanks in large part to mobile phones, the average person now carries one or more antennas on them wherever they go (cell phones can have multiple antennas).
This significant rate of growth is not likely to slow, as wireless communication systems become a larger part of everyday life.
In addition, the strong growth in RFID devices suggests that the number of antennas in use may increase to one antenna per object in the world.
Hence, learning a little about antennas couldn't hurt, and will contribute to one's overall understanding of modern world.
FDP-EC6602-AWP-Unit I-Antenna Parameters

5. ANTENNA THEORY HISTORY
What is the origin of the antenna?
Ben Franklin's kite experiment wasn't quite an antenna, as that captured lightning discharge, which is a direct current path where the energy is not transferred independent of the medium it travels. The human eye of course receives high frequency electromagnetic waves (light, to the layman).
Technically the eye could be classified as an antenna; however it can't transmit waves, it is really a sensor.
First experiments that involved the coupling of electricity and magnetism and showed a definitive relationship was that done by Faraday somewhere around the 1830s. He slid a magnetic around the coils of a wire attached to a galvanometer. In moving the magnet, he was in effect creating a time-varying magnetic field, which as a result (from Maxwell's Equations), must have had a time-varying electric field. The coil acted as a loop antenna and received the electromagnetic radiation, which was received (detected) by the galvanometer - the work of an antenna.
FDP-EC6602-AWP-Unit I-Antenna Parameters

6. ANTENNA THEORY HISTORY
Contributors
Maxwell ( ) Fundamental equations. (Scottish)
Hertz ( ) First aerial propagation. (German)
Marconi ( ) Transatlantic transmission.(Italian)
DeForest (Triode tube 1920) Signal generators.(American)
World War II ( ) Intense war-driven development.
Heinrich Hertz (1886 )developed a wireless communication system in which he forced an electrical spark to occur in the gap of a dipole antenna. He used a loop antenna as a receiver, and observed a similar disturbance.
Marconi(1901) was sending information across the Atlantic. For a transmit antenna, he used several vertical wires attached to the ground. Across the Atlantic Ocean, the receive antenna was a 200 meter wire held up by a kite.
In 1906, Columbia University had an Experimental Wireless Station where they used a transmitting aerial cage. This was a cage made up of wires and suspended in the air.
FDP-EC6602-AWP-Unit I-Antenna Parameters

7. ANTENNA THEORY HISTORY
Some major antennas and discovery:
Yagi-Uda Antenna, 1920s
Horn antennas, waveguides as "hollow metal pipes".
Antenna Arrays, 1940s
Parabolic Reflectors, late 1940s, early 1950s? Just a guess.
Patch Antennas, 1970s.
PIFA, 1980s.
Current research on antennas involves metamaterials, making antennas smaller, particularly in communications for personal wireless communication devices.
A lot of work is being performed on numerical modeling of antennas, so that their properties can be predicted before they are built and tested.
References
[1] Balanis, Constantine,"Antenna Theory: A Review", Proceedings of IEEE, vol. 80, Jan 1992.
[2]
FDP-EC6602-AWP-Unit I-Antenna Parameters

8. Converts Electrons to Photons of EM energy.
What is an Antenna?
An antenna is a way of converting the guided waves present in a waveguide, feeder cable or transmission line into radiating waves travelling in free space, or vice versa.
An antenna is a passive structure that serves as transition between a transmission line and air used to transmit and/or receive electromagnetic waves.
Converts Electrons to Photons of EM energy.
It is a transducer which interfaces a circuit and free space.
FDP-EC6602-AWP-Unit I-Antenna Parameters

9. Antenna as a Transition Device
Only accelerated (or decelerated) charges radiate EM waves.
A current with a time-harmonic variation (AC current) satisfies this requirement.
FDP-EC6602-AWP-Unit I-Antenna Parameters

10. Transmission-line Thevenin equivalent of antenna in transmitting mode
FDP-EC6602-AWP-Unit I-Antenna Parameters

11. Role of antennas?
FDP-EC6602-AWP-Unit I-Antenna Parameters

12. Antenna types Helical antenna Horn antenna Parabolic reflector antenna
FDP-EC6602-AWP-Unit I-Antenna Parameters
Helical antenna
Horn antenna
Parabolic reflector antenna

13. Solid angle, WA and Radiation intensity, U
Antenna parameters
Solid angle, WA and Radiation intensity, U
Radiation pattern, Pn, sidelobes, HPBW
Far field zone, rff
Directivity, D or Gain, G
Antenna radiation impedance, Rrad
Effective Area, Ae
All of these parameters are expressed in terms of a transmission antenna, but are identically applicable to a receiving antenna.
FDP-EC6602-AWP-Unit I-Antenna Parameters

14. Isotropic antenna
FDP-EC6602-AWP-Unit I-Antenna Parameters

15. Isotropic antenna
FDP-EC6602-AWP-Unit I-Antenna Parameters

16. FDP-EC6602-AWP-Unit I-Antenna Parameters

17. Field Regions Radian and Steradian
- measure of a plane angle is a radian & measure of a solid angle is a steradian.
FDP-EC6602-AWP-Unit I-Antenna Parameters

18. Radiation Intensity
FDP-EC6602-AWP-Unit I-Antenna Parameters

19. Radiation Pattern
FDP-EC6602-AWP-Unit I-Antenna Parameters

20. FDP-EC6602-AWP-Unit I-Antenna Parameters

21. Radiation Pattern Characteristics
FDP-EC6602-AWP-Unit I-Antenna Parameters

22. Radiation Pattern Lobes
Radiation lobes and beamwidths of an antenna pattern.
FDP-EC6602-AWP-Unit I-Antenna Parameters

23. Radiation Pattern Lobes
(b) Linear plot of power pattern and its associated lobes and beamwidths.
FDP-EC6602-AWP-Unit I-Antenna Parameters

24. Directivity and Gain
FDP-EC6602-AWP-Unit I-Antenna Parameters

25. Directivity and Gain of the Antenna
FDP-EC6602-AWP-Unit I-Antenna Parameters

26. Directivity or Gain
FDP-EC6602-AWP-Unit I-Antenna Parameters

27. Directivity and Gain
FDP-EC6602-AWP-Unit I-Antenna Parameters

28. Gain or Directivity
FDP-EC6602-AWP-Unit I-Antenna Parameters

29. Relation b/w Directivity, HPBW,ΩA
FDP-EC6602-AWP-Unit I-Antenna Parameters

30. Effective Aperture
FDP-EC6602-AWP-Unit I-Antenna Parameters

31. FDP-EC6602-AWP-Unit I-Antenna Parameters

32. Effective Aperture
FDP-EC6602-AWP-Unit I-Antenna Parameters

33. ANTENNA EFFICIENCY
total antenna efficiency (e0) is used to take into account losses at the input terminals and within the structure of the antenna.
FDP-EC6602-AWP-Unit I-Antenna Parameters

34. used to judge the quality of transmitting and receiving antennas.
BEAM EFFICIENCY
used to judge the quality of transmitting and receiving antennas.
FDP-EC6602-AWP-Unit I-Antenna Parameters

35. Linear, Circular, and Elliptical Polarizations
defined as “the polarization of the wave transmitted (radiated) by the antenna.
Polarization of a radiated wave is defined as “that property of an electromagnetic wave describing the time-varying direction and relative magnitude of the electric-field vector; specifically, the figure traced as a function of time by the extremity of the vector at a fixed location in space, and the sense in which it is traced, as observed along the direction of propagation.”
Linear, Circular, and Elliptical Polarizations
FDP-EC6602-AWP-Unit I-Antenna Parameters

36. Antenna Impedance
FDP-EC6602-AWP-Unit I-Antenna Parameters

37. Antenna Impedance
FDP-EC6602-AWP-Unit I-Antenna Parameters

38. Radiation Resistance
FDP-EC6602-AWP-Unit I-Antenna Parameters

39. Radiation Resistance
FDP-EC6602-AWP-Unit I-Antenna Parameters

40. Radiation Resistance
FDP-EC6602-AWP-Unit I-Antenna Parameters

41. So , Antenna Input Impedance is
FDP-EC6602-AWP-Unit I-Antenna Parameters

42. Antenna Bandwidth
FDP-EC6602-AWP-Unit I-Antenna Parameters

43. Antenna Bandwidth
FDP-EC6602-AWP-Unit I-Antenna Parameters

44. Antenna Bandwidth
• For broadband antennas, the bandwidth is usually expressed as the ratio of the upper-to-lower frequencies of acceptable operation. For example, a 10:1 bandwidth indicates that the upper frequency is 10 times greater than the lower.
• For narrowband antennas, the bandwidth is expressed as a percentage of the frequency difference (upper minus lower) over the center frequency of the bandwidth. For example, a 5% bandwidth indicates that the frequency difference of acceptable operation is 5% of the center frequency of the bandwidth.
FDP-EC6602-AWP-Unit I-Antenna Parameters

45. Antenna Temperature
Antenna Temperature is a property of an antenna and the environment it operates in. It is a measure of the noise received by the antenna due to thermal (or temperature) effects.
Every object with a physical temperature above absolute zero
(K = −273◦C) radiates energy.
The amount of energy radiated is usually represented by an equivalent temperature TB, better known as brightness temperature, and it is defined as,
FDP-EC6602-AWP-Unit I-Antenna Parameters

46. Baluns
FDP-EC6602-AWP-Unit I-Antenna Parameters

47. Baluns A balun is a type of transformer Used at RF
Impedance-transformer baluns having a 1:4 ratio are used between systems with impedances of 50 or 75 ohms (unbalanced) and 200 or 300 ohms (balanced). Most television and FM broadcast receivers are designed for 300-ohm balanced systems, while coaxial cables have characteristic impedances of 50 or 75 ohms. Impedance-transformer baluns with larger ratios are used to match high-impedance balanced antennas to low- impedance unbalanced wireless receivers, transmitters, or transceivers.
Usually band-limited
Improve matching and prevent unwanted currents on coaxial cable shields
As in differential signaling, the rejection of common mode current is the most important metric for an antenna feed balun, although performance also requires proper impedance ratios and matching to the antenna.
FDP-EC6602-AWP-Unit I-Antenna Parameters

48. Baluns Balun for connecting a center-fed dipole to a coaxial cable
Transition from a 50 Ω coaxial cable to a 300 Ω half-wave folded dipole through a four-to- one impedance transformation balun
FDP-EC6602-AWP-Unit I-Antenna Parameters

49. some basic sources of radiation. Single Wire Two-Wires
RADIATION MECHANISM
“how is radiation accomplished?” (or) how are the electromagnetic fields generated by the source, contained and guided within the transmission line and antenna, and finally “detached” from the antenna to form a free-space wave?
some basic sources of radiation.
Single Wire
Two-Wires
Radiation from oscillating dipole, Half wave dipole. Folded dipole, Yagi array.
FDP-EC6602-AWP-Unit I-Antenna Parameters

50. RADIATION MECHANISM - Single Wire
Conducting wires are material whose prominent characteristic is the motion of electric charges and the creation of current flow.
Charge uniformly distributed in a circular cross section cylinder wire.
to create radiation, there must be a time-varying current or an acceleration (or deceleration) of charge.
FDP-EC6602-AWP-Unit I-Antenna Parameters

51. RADIATION MECHANISM - Single Wire
To create charge acceleration (or deceleration) the wire must be curved, bent, discontinuous, or terminated.
1. If a charge is not moving, current is not created and there is no radiation.
2. If charge is moving with a uniform velocity:
a. There is no radiation if the wire is straight, and infinite in extent.
b. There is radiation if the wire is curved, bent, discontinuous, terminated, or truncated.
3. If charge is oscillating in a time-motion, it radiates even if the wire is straight.
FDP-EC6602-AWP-Unit I-Antenna Parameters

52. RADIATION MECHANISM - Single Wire
Wire configurations for radiation
FDP-EC6602-AWP-Unit I-Antenna Parameters

53. RADIATION MECHANISM - Two-Wires
Source, transmission line, antenna, and detachment of electric field lines.
FDP-EC6602-AWP-Unit I-Antenna Parameters

54. Current Distribution
Current distribution on a lossless two-wire transmission line, flared transmission line, and linear dipole.
FDP-EC6602-AWP-Unit I-Antenna Parameters

55. (Short )Dipole Antenna
simplest of all antennas. It is simply an open-circuited wire, fed at its center.
The dipole antenna is similar to the short dipole except it is not required to be small compared to the wavelength
"short" or "small" - "relative to a wavelength". So size of dipole antenna does not matter, only the size of wire relative to wavelength of the frequency of operation. Typically, a dipole is short if its length is less than a tenth of a wavelength.
Formation and detachment of electric field lines for short dipole.
FDP-EC6602-AWP-Unit I-Antenna Parameters

56. Half-Wave Dipole Antenna
half-wave dipole antenna is a special case of the dipole antenna.
length of this dipole antenna is equal to a half-wavelength at the frequency of operation.
input impedance of the half-wavelength dipole antenna is given by Zin = j42.5 Ohms.
directivity of a half-wave dipole antenna is 1.64 (2.15 dB). The HPBW is 78 degrees.
reducing the length slightly the antenna can become resonant. If the dipole's length is reduced to 0.48 wavelength, the input impedance of the antenna becomes Zin = 70 Ohms, with no reactive component. This is a desirable property, and hence is often done in practice.
FDP-EC6602-AWP-Unit I-Antenna Parameters

57. Yagi-Uda Antenna
Yagi antenna was invented in Japan, with results first published in 1926.
most brilliant antenna designs. It is simple to construct and has a high gain, typically greater than 10 dB.
Yagi-Uda antennas typically operate in the HF to UHF bands (about 3 MHz to 3 GHz), although their bandwidth is typically small, on the order of a few percent of the center frequency.
FDP-EC6602-AWP-Unit I-Antenna Parameters

58. Geometry of Yagi Antenna
consists of a single 'feed' or 'driven' element, typically a dipole or a folded dipole antenna.
feed antenna is often altered in size to make it resonant in the presence of the parasitic elements (typically, wavelengths long for a dipole antenna).
adding more reflectors improves performance very slightly. This element is important in determining the front-to-back ratio of the antenna.
reflector slightly longer than resonant & impedance of the reflector will be inductive.
directional antenna.
FDP-EC6602-AWP-Unit I-Antenna Parameters

59. CONCLUSIONS
To describe the performance of an antenna, definitions of various parameters are necessary.
Some of the parameters are interrelated and not all of them need be specified for complete description of the antenna performance.
Many of those in quotation marks are from the IEEE Standard Definitions of Terms for Antennas (IEEE Std ). (Revision of the IEEE Std ).
FDP-EC6602-AWP-Unit I-Antenna Parameters

60. REFERENCES
Constantine.A.Balanis “Antenna Theory Analysis and Design”, Wiley Student Edition, 2006.
John D Kraus,” Antennas for all Applications”, 3rd Edition, Mc Graw Hill, 2005.
R.E.Collin,”Antennas and Radiowave Propagation”, Mc Graw Hill
H.Sizun “Radio Wave Propagation for Telecommunication Applications”, First Indian Reprint, Springer Publications, 2007.
FDP-EC6602-AWP-Unit I-Antenna Parameters

61. THANK YOU
FDP-EC6602-AWP-Unit I-Antenna Parameters