Pune, India, 13 – 15 December 2010

ITU-T Kaleidoscope 2010Beyond the Internet? - Innovations for

future networks and services

Pranoti S. BansodeUniversity of Pune.

Dr.RajkumarDefense Institute of Advanced Technology(DU),Pune.

Presented byPranoti S.Bansode

pranoti2009@yahoo.com

ON THE DESIGN OF ULTRA WIDE BAND ANTENNA BASED ON FRACTAL

GEOMETRY

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

Ultra short pulses High data rate

Unique features

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

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

The experimental result of circular fractal antenna exhibits the ultra wide band characteristics from 3.295GHz to 13.365GHz correspondence to 120.88% 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

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 2 4 4

Radii 1 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 3.2mm 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.44mm

40mm

3.2mm

0.7mm0

.5m

m

Pune, India, 13 – 15 Dec 2010: ITU-T Kaleidoscope 2010 – Beyond the Internet? Innovations for future networks and services 17

To achieve the ultra wide band characteristic the gap between patch and ground has been optimized to h=0.5mm.

Result by Optimizing the gap between patch and ground.

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 3.75 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 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.

Current distribution

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 radiation patterns in H-plane have been measured at frequencies 4.2 GHz 7.0 GHz,8.775 GHz and 10.1 GHz.

The H plane pattern is nearly Omni directional.

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, 8.325 GHz and 9.525 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 3.295 GHz to 13.365 GHz corresponds 120.88 % 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. 26-28, 2004.

 [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. 517-524, (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. 1179-1180, 2000.

 [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 1998.

 [5] M. Hammoud, P. Poey, F. Colombel,” Matching the Input Impedance of a

Broadband Disc Monopole,” Electronics Letters, Vol. 29, no. 4, pp. 406-7, 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!!!