Advantages and Applications of Fractial Antennas

Advantages of fractal Antennas

• Minituratization
• Better input impedance matching
• Wideband/multiband (use one antenna instead of many)
• Frequency independent (consistent performance over huge freq range)
• Reduced mutual coupling in fractal array antennas

Disadvantages of fractal Antennas

• Gain loss
• Complexity
• Numerical limitations
• The benefits begins to diminish after first few iterations

Commercial Applications

There are many applications that can benefit from fractal antennas. The sudden grow in the wireless communication area has sprung a need for compact integrated antennas. The space saving abilities of fractals to efficiently fill a limited amount of space create distinct advantage of using integrated fractal antennas over Euclidean geometry. Examples of these types of application include personal hand-held wireless devices such as cell phones and other wireless mobile devices such as laptops on wireless LANs and networkable PDAs and RFID. Fractal antennas can also enrich applications that include multiband transmissions. This area has many possibilities ranging from dual-mode phones to devices integrating communication and location services such as GPS, the global positioning satellites. Fractal antennas also decrease the area of a resonant antenna, which could lower the radar cross-section (RCS). This benefit can be exploited in military applications where rcs of antenna is a crucial parameter.

a) In Building Communication: Fractal antenna provides universal wideband antenna technology that is ideal for in building communication applications. Operating over 150MHz to 6GHz, fractal antennas deliver excellent Omni directional coverage in a compact form factor.

b) Wireless Networks: Fractal Antenna Systems provide excellent advanced antenna technology that enables merging wireless protocols, such as ZigBee, WiMAX and MIMO, to deliver their maximum potential.

c) Universal Tactic Communication: Future communications systems will use cognitive radios that require vast bandwidths, with one antenna.

d) Mobile Devices: From PDAs to cellular phones to mobile computing, today’s wireless devices require compact, high performance multiband antennas. At the same time, packaging constraints demand that each component, especially the antenna, be inherently versatile.

e) Telematics: Today’s automobile can have dozens of antennas that provide everything from emergency notification and navigational services to satellites radio and TV. Multiple antennas create performance and form factor challenges, as well as aesthetic design issues.

f) RFID (Radio frequency identification): Fractal antenna system provides a compact, low cost solution for multitude of RFID applications. Because fractal antennas are small and versatile, they are ideal for more compact RFID equipment.

Military Applications

Modern military uses of antennas have presented new challenges to the antenna designer. Only a decade ago, specific band antennas, or tall whips, met the needs of most communications, electronic warfare (EW) and surveillance applications. But with new needs and transceiver technologies, antennas have new challenges: wideband; small; and agile platforms, for software-defined radio (SDR) and modern EW, among others.

The outstanding problem with military oriented antennas is that they are too big, too narrow-band, and too many are needed. With fractal antennas, a new era has arisen where the important attribute surfaces that form no longer follows function. Previously, the performance and even application of an antenna was easily discerned from its form factor and appearance. While at the extremes, this is still true, combining fractal antenna attributes of self-scaling and fractal loading produces extremely wideband antennas with multiple functions and small sizes.

EW. In electronic warfare, disrupting communications is a daunting task because of the plethora of frequency ranges available to a hostile foe. Most other antennas are not wideband but multiple band compromises that prevent allowance for future capability when the environment changes. In this application, the wideband capability of fractal antennas allows smaller antennas that have from 10:1 to 200:1 bandwidths that can handle moderate to high power. This allows fewer antennas to meet extant and future threats. As form no longer follows function, it also thwarts the ability for the foe to understand the capability of the system, in addition to adding a huge versatility to how the system may be deployed. Vehicular use is vastly aided by these advantages.

Sigint. Surveillance and information gathering is always limited by the covertness of the antenna. In general, small antennas mean limited reach and limited frequency range. Fractal antennas have been produced that have wide bandwidths, but also fit covertly in packages where no antenna is expected. Indeed, transparent antennas, when combined with fractal wideband capabilities, make proven examples of such. Figure 7 shows one such example, with a 100:1 bandwidth. Where is it? Follow the coaxial cable to see the connection point to the window-mounted antenna.

Universal tactical communications. Future communications systems will use cognitive radios that require vast bandwidths, with one antenna. For the soldier, this spells the need for a single antenna, or simple antenna system, that can be body-worn, and not physically interfering with other needs. Since 1997, fractal antennas have been used to make body worn antennas that have the fewest compromises and work best for most terrestrial and SatCom applications.

Conclusion

The main goal of this paper is to design and develop sierpinski microstrip fractal antenna for wireless applications. The basics of microstrip fractal antenna are studied in detail and also all the design considerations of this antenna is been examined. Thus here size reduction along with the large bandwidth and high gain are the major considerations for designing the antenna. For designing a microstrip fractal antenna various designing steps corresponding to the antenna parameters have been examined. According to the designing parameters the relevant feeding techniques are selected. The antenna is designed and simulated using HFSS.

The sierpinski carpet antenna is designed in an operating frequency 2.45 GHz and simulated. The three iteration stages of sierpinski carpet antenna are studied and obtained the simulation results. The various design parameters such as return loss, VSWR, radiation pattern, gain plot etc are obtained using simulation. It is observed that with increase in the number of iterations the bandwidth of the antenna increases & on second iterations the antenna starts showing the multiband behavior. As the no. of iterations increases the effective area of the antenna structure is reduced. Increase in multiple iterations also led to improvement in various performance parameters like VSWR, directivity, gain & return losses. The simulated results shows good band width enhancement.

Future Work

In this thesis different types of compact fractal antennas are studied for wideband operation. Based on this, future work may be carried out such as:

• The effect of material properties on Fractal antenna performance such as gain, efficiency, radiation patterns, etc. can be studied.
• Study of new tech to reduce the size and enhance the bandwidth of fractal wideband antennas for use in mobile and portable devices.
• Fabrication of the proposed Fractal antennas and comparison of simulated results with the measured results.