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1. Traveling Wave Antenna
Antenna Theory
Prepared by
Abdelaziz Said
Electrical Engineering
Department
New Cairo Academy

2. - Traveling wave antenna is non-resonant
type antenna or aperiodic antenna
Definitions
- The antenna in which the standing wave
does not exist along the length of the
antenna is called traveling wave antenna

3. Q1
What is the difference between standing
wave and traveling wave ?
Q2
What is the difference between resonant
and non-resonant antenna ?

5. 1- Long Wire Antenna
An antenna is usually classified as a long wire
antenna if it is a very straight conductor with a
length from one to many wavelengths
Antenna Height (h)

6. Total field radiated by the wire
 It is found by multiplying the field radiated by the wire in free space
by the array factor of a two-element array
 the wave travels along the wire from the source toward the load, it
continuously leaks energy (attenuation coefficient)
Field radiated in free space
Radiated by long wire to free space

7. Current distribution along structure
 If = aˆz Iz (z΄) e− γ(z΄)z΄ = az I0 e−[α(z΄)+jkz(z΄)]z΄
 By approx. : If = aˆz Iz (z΄) e− jKz Z΄ = az I0 e− jKz Z΄
 K =
𝐾𝑧
𝐾
=
λ
λ𝑔

8. it is evident that the power distribution of a wire antenna of length l is a multi lobe
pattern whose number of lobes depends upon its length.
To calculate Peaks of lopes

9. For angles the peaks occur
To find nulls
Angles where the nulls occurs

10. Total radiated power
Radiation resistance
Directivity

12. Design long wires
Amplitude pattern , maxima and nulls

13. Input Impedance

14.  Provides strong Minor Lobes
Disadvantages
 Easy to Construct
 More Cheap than V antenna
 More simple
 Larger Bandwidth
 Input impedance is High

15. Applications
 Commercial applications
 Mellatry applications
 For RF communications
 Microwave communications
 Long Closed places likes tunnels

16. 2- V Antenna
The V antenna is made up of two wire antenna which are
arranged in the form of the horizontal V and it is fed at the
apex by the transmission feed line.
For some applications a single long-wire antenna is not very
practical because
(1) its directivity may be low.
(2) its side lobes may be high.
These and other drawbacks of single long-wire antennas can be
overcome by utilizing an array of wires, One very practical array of
long wires is the V

17.  There are two Types:
 Resonant V antenna
 Non-Resonant V antenna

20. Most V antennas are symmetrical (θ1 =θ2 =θ0 and l1 =l2 =l).
Also V antennas can be designed to have unidirectional or
bidirectional radiation patterns, as shown in Figures

23.  Easy to Construct
 Cheap
 Provides strong Minor Lobes
 On Light Aircraft
 Military appliances
 Commercial appliances

24. 3- Rhombic Antenna
Two V antennas can be connected at their open ends to form a
diamond or rhombic antenna, The antenna is usually terminated
at one end in a resistor, usually about 600–800 ohms, in order to
reduce if not eliminate reflections

26. - Radiation Pattern
 Unidirectional Pattern
 Lobes = 2 to 8 long
 Directivity : 20 to 90
 Power Gain : 50 to 60
 β value = 17 to 24 degree 

27. Assignment

- Design of Rhombic antenna

28.  The tilt angle ()
 The leg length (L)
 The height above the ground (h)
 Two designs
(a) Alignment design
(b) Maximum output design
- Design of Rhombic antenna

30. (a) Alignment design
h is chosen that max of the main lobe coincides with the desired angle of elevation 


sin4
h


2
sin
37.0
L   90

31. (b) Maximum field intensity design
h is chosen that max filed intensity is obtained at the desired elevation angle 
mh


sin4

mL


2
sin2
   90

32.  Highly directional
 Simple & cheap
 Needs larger space for installation
 Efficiency is Low
 HF transmission & reception

33. Thank you…