traveling wave antenna
TRANSCRIPT
![Page 1: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/1.jpg)
Traveling Wave Antenna
Antenna Theory
Prepared byAbdelaziz Said
Electrical Engineering Department
New Cairo Academy
![Page 2: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/2.jpg)
- 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
![Page 3: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/3.jpg)
Q1What is the difference between standing wave and traveling wave ?
Q2What is the difference between resonant and non-resonant antenna ?
![Page 4: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/4.jpg)
![Page 5: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/5.jpg)
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)
![Page 6: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/6.jpg)
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
![Page 7: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/7.jpg)
Current distribution along structure If = aˆz Iz (z΄) = z I0
By approx. : If = aˆz Iz (z΄) = z I0
K ==
![Page 8: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/8.jpg)
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
![Page 9: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/9.jpg)
For angles the peaks occur
To find nulls
Angles where the nulls occurs
![Page 10: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/10.jpg)
Total radiated power
Radiation resistance
Directivity
![Page 11: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/11.jpg)
![Page 12: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/12.jpg)
Design long wires
Amplitude pattern , maxima and nulls
![Page 13: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/13.jpg)
Input Impedance
![Page 14: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/14.jpg)
Advantages
Provides strong Minor Lobes
Disadvantages
Easy to ConstructMore Cheap than V antennaMore simpleLarger Bandwidth Input impedance is High
![Page 15: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/15.jpg)
Applications Commercial applications Mellatry applications For RF communications Microwave communications Long Closed places likes tunnels
![Page 16: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/16.jpg)
2- V AntennaThe 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
![Page 17: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/17.jpg)
There are two Types: Resonant V antenna Non-Resonant V antenna
![Page 18: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/18.jpg)
![Page 19: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/19.jpg)
![Page 20: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/20.jpg)
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
![Page 21: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/21.jpg)
![Page 22: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/22.jpg)
![Page 23: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/23.jpg)
Easy to ConstructCheap
Disadvantages
Advantages
Provides strong Minor Lobes
ApplicationsOn Light Aircraft Military appliancesCommercial appliances
![Page 24: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/24.jpg)
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
![Page 25: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/25.jpg)
![Page 26: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/26.jpg)
- Radiation Pattern
Unidirectional Pattern Lobes = 2 to 8 long Directivity : 20 to 90
Power Gain : 50 to 60 β value = 17 to 24 degree
![Page 27: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/27.jpg)
Assignment
- Design of Rhombic antenna
![Page 28: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/28.jpg)
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
![Page 29: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/29.jpg)
![Page 30: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/30.jpg)
(a) Alignment design h is chosen that max of the main lobe coincides with the desired angle of elevation
sin4
h
2sin37.0
L 90
![Page 31: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/31.jpg)
(b) Maximum field intensity designh is chosen that max filed intensity is obtained at the desired
elevation angle
mh
sin4
mL
2sin2
90
![Page 32: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/32.jpg)
Highly directional Simple & cheap
Disadvantages
Advantages
Needs larger space for installationEfficiency is Low
ApplicationsHF transmission & reception
![Page 33: Traveling Wave Antenna](https://reader033.vdocument.in/reader033/viewer/2022061617/58f221de1a28ab566e8b45af/html5/thumbnails/33.jpg)
Thank you…