1. ON THE DESIGN OF ULTRA WIDE BAND ANTENNA BASED ON FRACTAL GEOMETRY
ITU-T Kaleidoscope 2010 Beyond the Internet? - Innovations for future networks and services
ON THE DESIGN OF ULTRA WIDE BAND ANTENNA BASED ON FRACTAL GEOMETRY
Pranoti S. Bansode
University of Pune.
Dr.Rajkumar
Defense Institute of Advanced Technology(DU),Pune.
Presented by
Pranoti S.Bansode
Pune, India, 13 – 15 December 2010

2. Ultra wideband(UWB)
Definition: Ultra-wideband is a radio technology that can be used at very low energy levels for short-range high-bandwidth communications by using a large portion of the radio spectrum.
UWB radio transmissions can legally operate in the range from 3.1 GHz up to 10.6 GHz, at a limited transmit power of -41dBm/MHz.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

3. High energy efficiency
Unique features
Ultra short pulses
High data rate
Low duty cycle operation
High energy efficiency
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

4. Abstract
Ultra wide band circular fractal antenna which is fed with coplanar waveguide This fractal antenna has been designed and fabricated on FR4 substrate εr=4.3 and thickness h=1.53mm with initial diameter of solid circular disc of 15mm.
Substrate dimensions have been 44mm*40mm.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

5. Coplanar waveguide(CPW)
Coplanar waveguide consist of a center strip with two ground planes located parallel to and in the plane of the strip.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

6. It has lower dispersion characteristics at higher frequencies.
The 50 Ohm impedance is matched by adjusting the gap between stripline and ground plane
Advantages:
It has lower dispersion characteristics at higher frequencies.
Broader impedance bandwidth.
It have best ability to taper into a pin.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

7. This indicates the size reduction of an antenna.
The experimental result of circular fractal antenna exhibits the ultra wide band characteristics from 3.295GHz to GHz correspondence to % impedance bandwidth.
The resonant frequency of simple circular disc monopole antenna is 4.31GHz which is shifted to 3.71GHz in circular fractal antenna.
This indicates the size reduction of an antenna.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

8. This antenna exhibits the properties, -Miniature size. -Low resonance.
-wide band phenomenon.
-Omni directional radiation pattern.
Advantages:
Light weight, Low profile, low cost & ease of fabrication, easy to integrate with RF devices and MIC/MMIC.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

9. Fractal Antenna
A fractal is a rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole."
Features:-
1) It has a fine structure at arbitrarily small scale.
2)It is self-similar.
3) It has a simple and recursive definition.
4)Fractal antennas are multi-resonant and smaller in size.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

10. Properties of fractal Antenna
1.Self similarity:
It helps to achieve multiband characteristics.
2.Infinite Perimeter:
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

11. 3.Fractal in Telecommunication systems:
Here, Five different antennas for
five different Frequencies
In Fractal, Five different
frequencies in only One antenna..
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

12. Descartes Circle Theorem:
Antenna Design
Descartes Circle Theorem:
If four mutually tangent circles have curvatures Ki (i=1,2,..4)Descartes theorem says,
To find the radius of the fourth circle tangent to the three given touching circles then the equation is written as,
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

13. The fractal antenna has been constructed based on Descartes circle theorem the dimension of each iteration can be calculated with the help of following table.
Initiator
0th
Iteration
1st Iteration
2nd Iteration
3rd Iteration
4th Iteration
No. of circles generate-d 1 2 4
Radii
1/2
1/3
1/6
1/11
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

14. Iterationwise Geometry:
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

15. Resonant frequency of the simple microstrip antenna can be calculated by,
Where Vo is the velocity of light.
The effective radius reff can be calculated by the following expression,
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

16. The impedance matching have been achieved by adjusting the width 3
The impedance matching have been achieved by adjusting the width 3.2mm of the inner conducting and optimizing the gap between the ground plane and feed width to g=0.7mm i.e. 70Ω for wide bandwidth.
0.5mm
0.7mm
40mm
3.2mm
44mm
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

17. Result by Optimizing the gap between patch and ground.
To achieve the ultra wide band characteristic the gap between patch and ground has been optimized to h=0.5mm.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

18. Result by Optimizing the ground length.
The length of ground plane GL=14.17mm and width of the ground plane GW=19.7mm.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

19. Result by taking Iterations in the design.
As we increases the no. of iterations in a design the first resonant frequency is shifts to the lower side and higher frequencies gets added in it.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

20. The first resonant frequency of conventional simple circular disc monopole antenna is at
4.31 GHz.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

21. Result of disc monopole antenna:
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

22. The first resonant frequency of circular disc fractal antenna is at 3
The first resonant frequency of circular disc fractal antenna is at 3.75 GHz
So, it shows that as no. of iterations increases frequency shifts to the lower side and higher frequencies gets add. This indicates the size reduction of an antenna.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

23. Result of circular fractal antenna:
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

24. Current distribution
Current distribution of the proposed antenna is mainly along the circumference of the circular disc.
The current density is low in the middle area of the solid circular disc monopole antenna
Therefore, the current will not be affected if the middle area metallization of the solid circular disc monopole antenna is removed by circular or other geometrical pattern.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

25. Removing some portion of metallization from solid circular disc increases the effective path of the surface current.
In this antenna, the effective length of current path is increased by inscribing circle patterns inside solid circular disc using Descartes circle theorem.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

26. Radiation pattern
It is the mathematical function or a graphical representation of the radiation properties of the antenna as a function of space co-ordinates.
The radiation in azimuth as well as elevation plane has been measured at selective frequencies.
The H plane pattern is nearly Omni directional and monopole like radiation pattern in E plane and it is stable throughout the band.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

27. H-Plane radiation pattern
The H plane pattern is nearly Omni directional.
The radiation patterns in H-plane have been measured at frequencies 4.2 GHz 7.0 GHz,8.775 GHz and 10.1 GHz.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

28. E-Plane radiation pattern :
Monopole like radiation pattern in E plane.
The radiation patterns in E-plane have also been measured at frequencies 6.6 GHz, GHz and GHz as shown in Figure.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

29. Conclusion
It is observed as iterations increases, first resonant frequency shifts to the lower frequency side, thus yielding size reduction of the antenna.
The measurement results exhibits the excellent UWB characteristics in the wide range from GHz to GHz corresponds % impedance bandwidth and good radiation pattern.
The Ultra wide band characteristics achieved by using CPW fed and Fractal concept.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

30. UWB Applications: Wireless communication systems: -LAN & PAN
-Roadside info-station
-Short range radios
-Military communication
Radar and sensing:
-Vehicular radar
-Medical imaging
-Surveillance
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

31. References :
[1]L. Yang and G. B. Giamalkis, “Ultra wide band Communications,” “IEEE signal processing magazine, Nov. pp , [2] C. P. Baliarda, J. Romeu, R. Pous, and A. Cardama,”On the behavior of the Sierpinski multiband fractal antenna,” IEEE Trans Antennas Propagat. Vol. 46, pp , (1998). [3] R.V. Haraprasad, Y. Purushottam, V.C. Misra, and N.Ashok,,” Microstrip fractal patch antenna for multiband communication,” Electron Lett. Vol. 36, pp , [4] N. P. Agrawall, G. Kumar, K. P. Ray,” Wide-Band Planar Monopole Antennas,” IEEE Transactions on Antennas and Propagation, Vol. 46, no. 2, pp.294-5, February [5] M. Hammoud, P. Poey, F. Colombel,” Matching the Input Impedance of a Broadband Disc Monopole,” Electronics Letters, Vol. 29, no. 4, pp , 18th February 1993.
Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services

32. Thank you!!! Pune, India, 13 – 15 Dec 2010:
ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services