FRACTAL ANTENNAS
Karthikeya . G . S USN:1BM06EC042 Dept. of Electronics and communication B.M.S College of engineering, Bangalore-560019 Email id: [email protected]
OVERVIEW
Introduction
Fundamentals of radiation
Mathematics of fractals
Crux of the story( fractal antennas)
Design of these antennas with examples
Radiation pattern and other parameters
Applications,summary
References
WHY FRACTAL ANTENNAS?
Inspired by nature
Frequency decides the type, size of antenna
Increased expenditure
Heavy congestion in data traffic
Space problems to install larger antennas
Standard frequencies decide the design procedure
Gain optimization not possible
HOW DOES AN ANTENNA RADIATE?
THE TWO FLAVOURS IN ANTENNAS
ELECTRIC DIPOLE MAGNETIC DIPOLE
WHAT DO FRACTALS MEAN??
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,
Fine structures at arbitrarily small scales
Euclidean geometry’s jargon fails to describe it
It has a self similar structure with a fractional dimension
It has a simple recursive definition
Examples: Mandelbrot set, Koch snowflake, Sierpinski triangle, Lyapunov fractal etc….
SOME IMAGES
MATHEMATICS OF FRACTALS
HOW ARE THEY GENERATED?
Using simple quadratic transformation like Q(z) = z^2+C
Using iterated function system(IFS)……chaos game
Affine transformations(linear+ translation……………Ax+B)
Starting symbol production rules Iterations
PROPERTIES OF FRACTALS
Continuous everywhere
Differentiable nowhere
Dimension greater than 1
Self similar
Parameterizations are difficult to implement
FRACTAL ANTENNAS
A fractal antenna is an antenna that uses a fractal, self-similar design to maximize the length, or increase the perimeter (on inside sections or the outer structure), of material that can receive or transmit electromagnetic radiation within a given total surface area or volume.
HOW DID THEY BECOME MULTIBAND ANTENNAS
EXAMPLES
all these patterns do not qualify to be a radiating structure it depends strongly on the ease of implementation
These examples are very crucial as the design criteria, radiation parameters are all based on them
1.The Koch monopole
Some Performance parameters of Koch antenna
RADIATION PATTERN OF KOCH MONOPOLE ANTENNA
2.Sierpenski gasket dipole
3. Sierpinski fractal antenna 4.Hilbert curve fractal monopole antenna
5. Multi ring fractal antenna 5. Peano fractal antenna
DESIGN AND RETURN LOSS GRAPHS OF A HILBERT FRACTAL ANTENNA WITH VARIOUS ITERATIONS
CONTINUED……………..
RADIATION PATTERNS
ANTENNA TESTING
Dedicated indoor range
Outdoor range
Specialized testing
Feature Advantage Benefit
Wideband Speedy spectrum access
Use of one antenna instead of many
Compact More design and use versatility
Lowers cost
Fractal ground plane Smaller/multiband Greater versatility and new packaging options
Frequency independent
Consistent performance over huge frequency range
Solutions open to unknown options
Low mutual coupling Close packing of antenna
Small arrays with great steerability
Proven products Designed for harsh conditions
In use by military and commercial users
DISADVANTAGES
Heavy computing power need to model these antennas
Higher iteration fractals are difficult to fabricate
Power matching techniques at miniature scale is of paramount difficulty
Expensive for prototyping the design since it is mainly a trial and error process
Various polarization schemes are difficult to implement
SPECIFIC APPLICATIONS OF FRACTAL ANTENNAS
RFID applications
Band pass filter
metacloak
Bluetooth, GSM
Automated meter reading
Satellite radio, navigation systems
Electronic warfare
Fractal antenna system for improved wireless telecommunication
SUMMARY
•Geometry of fractals was investigated•The algorithm to generate fractals was learnt•The fundamentals of radiation was learnt (A classical physics approach)•Combination of both the fields lead to fractal antennas•The benefits ,challenges and disadvantages of these antennas were considered•The manufacturability of fractal antennas was considered•Applications of fractal antennas were considered
REFERENCES
•http://library.thinkquest.org/3493/frames/fractal.html•http://www.ccs.neu.edu/home/fell/COM1201/PROGRAMS/RecursiveFractals.html•http://en.wikipedia.org/wiki/Fractal•http://www.math.lsa.umich.edu/mmss/coursesONLINE/chaos/chaos7/index.html•www.fractus.com•www.fractenna.com•Best, S, (2003). "A Comparison of the Resonant Properties of Small Space-Filling Fractal Antennas". IEEE Antennas and Wireless Propagation Letters 2 (1): 197-200. http://www.physics.princeton.edu/~mcdonald/examples/EM/best_ieeeawpl_2_197_03.pdf.•FRACTAL ANTENNAS Mircea V. Rusu, Physics Faculty, Bucharest University, Roman Baican, Adam Opel AG. Russelheim, Germany, Ioana ENE, University "Politehnica" Bucharest, Romania 9. Generalized Sierpinski Fractal Multiband Antenna Jordi Romeu and Jordi Soler IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 49, NO. 8, AUGUST 2001 10. Performance characteristics of Minkowski curve fractal antennas M.Ahmed and others journal of engineering and sciences, 2006 11. Fractal antennas literature study by Philip Felber