study and performance analysis of uwb antenna for uwb ccommunication systems

ISSN: 2395-0560 International Research Journal of Innovative Engineering

www.irjie.com Volume1, Issue 3 of March 2015

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Study and Performance Analysis of UWB Antenna for UWB

Ccommunication Systems Hridesh Kumar Verma1, Dr. Praveen Kumar Maduri2, Deepanshu Bhargava3, Gaurav Yadav4,

Himanshu Pandey5

1, 2,3,4,5 Department of Electronics and Instrumentation Galgotias College of Engineering and Technology, Greater Noida-201306

Abstract In this article, recent papers on UWB antennas are studied; different geometries, design parameters and their experimental results are discussed. Several types of UWB antennas in recent papers are described together while comparing their measured dimension, gain and radiation patterns. The circuits have taken into consideration uses various substrate materials with different dielectric constants. The performance of the various circuits has been observed by comparing various parameters. INTRODUCTION

In this paper we have compared and analyzed four different UWB antenna circuits presented in different journals. The first circuit we took into consideration was presented by Rezaul Azim and Mohammad Tariqul Islam. They discussed about a compact micro strip line-fed ultra wideband (UWB) tapered-shape slot antenna in their paper named Compact Tapered-Shape Slot Antenna for UWB Applications in 2011[1]. Further in the second circuit considered, Jian Yang and Ahmed Kishk novel compact low-profile directional UWB antenna. The paper was published in march 2012, named as A novel compact low-profile directional UWB antennathe self-grounded Bow-Tie antenna[2].The third circuit that we studied was presented by Anil Kr Gautam, Swati Yadav and Binod Kr Kanaujia in 2013 .This paper was published under the name A CPW-Fed Compact UWB Micro strip Antenna[3]. In this paper, the authors have proposed a novel coplanar waveguide (CPW)-fed compact ultra wideband (UWB) micro strip antenna for ultra wideband applications. Finally the fourth paper we discussed was published by Thomas Peter, Tharek Abd Rahman, S. W. Cheung, Rajagopal Nilavalan, Hattan F. Abutarboush and Antonio Vilches named A Novel Transparent UWB Antenna for Photovoltaic Solar Panel Integration and RF Energy Harvesting [4]. The paper was published in the year 2014. In this paper a transparent cone top tapered slot antenna covering the frequency range from 2.2 to 12.1 GHz has been designed.

The admiral benefits of a wireless lifestyle have resulted in a huge demand for advanced wireless communications. The quick tempered growth of the wireless coomunication market is expected to continue in the future since the claim of all wireless services is increasing.

Transparent antennas for communications have been researched on by only a dedicated few for the last two decades .An antenna is a transducer that transforms guided electromagnetic energy in a transmission line to radiated electromagnetic energy in free space. Antennas may also be viewed as an impedance transformer, coupling between an input or line impedance, and the impedance of free space. [5] In 2002, the Federal Communications Commission (FCC) allocated the spectrum from 3.1 to 10.6 GHz [Fig.1] for unlicensed ultra wideband (UWB) measurements and communication applications with EIRP less than 41.3 dB/MHz. Since then, UWB has been considered as one of the most promising wireless technologies to revolutionize high data transmission.

. Figure. 1 Bandwidth allocation




At present, attractive characteristics of ultra wideband (UWB) technology like low cost, low complexity, low spectral power density, high data resolution, very low interference, and extremely high data transmission rates have made it a potential candidate in various wireless communications. For different wireless communication applications, a UWB antenna must be electronically small and inexpensive without degrading the performance. Stable omnidirectional radiation patterns, gain flatness, and linear phase variation are also required to fulfill the requirements for UWB applications. [1] Thus, the UWB antenna has become the most promising solution for future short-range, high-data, wireless communication applications, UWB for short-range (10 m), peer-to-peer ultra-fast communications, and many more application. The imminent widespread commercial deployment of ultra-wideband (UWB) systems has sparked renewed interest in the subject of ultra-wideband antennas. UWB antennas have been in active commercial use for decades. In a sense, even the venerable AM broadcast band antenna is UWB since it covers a band from 535- 1705 kHz for a fractional bandwidth in excess of 100%. Because a high quality broadcast AM antenna is really a tuned antenna designed to pick up an individual narrowband (10 kHz) channel, the effective fractional bandwidth is really only 0.6-1.9% and only one channel can be received at a time. UWB antenna is usually preferred as UWB technology transmit and receive pulse based waveform compressed in time. Because of compressed time pulse data rate is very high and as the power of pulse is spread over the large frequency band so noise interference is very less.

Many planar antennas have been anticipated for UWB applications. Among planar UWB antennas, the printed slot antenna type is one of the most suitable candidates for UWB applications. A conventional narrow slot antenna has limited bandwidth, whereas wide-slot antennas exhibit wider band-width. Recently, different printed wide-slot antennas fed by a micro strip line or coplanar waveguide (CPW) have been reported. The monopole-like slot antennas have also been reported to have wide bandwidth characteristics in. By using different tuning techniques or employing different slot shapes, different slot antennas with wideband or ultra-wide band performance can also be achieved. In addition, a UWB antenna is preferentially non- dispersive, having a fixed phase center. If waveform dispersion occurs in a predictable fashion it may be possible to compensate for it, but in general it is desirable to radiate similar waveforms in all directions. A log- periodic antenna is an example of a dispersive antenna. Larger scale components radiate low frequency components while smaller scale components radiate high frequency components. The result is a chirp-like, dispersive waveform. Worse, the waveform will vary at different azimuthal angles around the antenna. Again, a multi-band or OFDM approach may be more tolerant of dispersive antennas. [6]

HISTORY of UWB ANTENNA

Ultra-wideband has its origins in the original spark-gap transmitters that initiated radio technology. [7] UWB systems have been historically based on impulse radio since it has transmitted very high data rates by sending pulses of energy instead of using a narrowband frequency carrier. The concept of impulse radio dates back to the pulse based spark gap radio developed by Guglielmo Macroni in the late 1800s. It was used for several decades to transmit Morse code through the airwaves. Ironically, the very patent which initiated the concept of narrowband frequency domain radio also revealed some of the first ultra-wideband antennas. In 1898, Oliver Lodge presented the idea that a transmitter and a receiver should be tuned to the same frequency so as to maximize the received signal. Lodge disclosed spherical dipoles, square plate dipoles, biconical dipoles, and triangular or bow-tie dipoles. He also introduced the concept of a monopole antenna using the earth as a ground.

Figure 2: Lodge preferred antennas

As frequencies increased and waves became shorter, the economic advantages of a thin-wire quarter wave antenna superseded any performance advantages of Lodges original designs. With the advent of research into television however, interest in antennas that could handle the much wider bandwidths associated with video signals increased.




Figure 3: Lodges biconical antennas (1898).

This renewed interest in wideband antennas led to the discovery of different type of antenna by researchers which improves the Lodges original designs and also led to high performances. Figure 4a and 4b shows the improved version of Lodges Antennas.

Figure 4a (left): Carters biconical antenna (1939)

Figure 4b (right): Carters conical monopole (1939).

The most notable UWB antenna of that period was Lindenblads coaxial horn element shown in Figure 5. Lindenblad improved on the idea of a sleeve dipole element, adding a gradual impedance transformation to make it broader banded. For several years during the 1930s, a turnstile array of Lindenblads coaxial horn elements graced the top of the Empire State Building in New York City where RCA located its experimental television transmitter.

Figure 5a (left): Lindenblads element in cross- section Figure 5b (right): A turnstile array o f L i n d e n b a l d elements for television transmission (1941).

In the late 1960s, significant research was conducted by antenna designers. As a result of these antenna advances, the development of short pulse radar and communication systems has begun. For the nearly 40 year period of 1960-1999, over 200 papers were published in accredited IEEE journals and more than 100 papers were filed on topics related to ultra wide band technology.[8]




Although standing designs presented excellent performance, other consideration began to become important. As broadband receivers came into common use, emphasis on inexpensive, easily manufactural designs increased.On February 14, 2002, FCC permitted the commercial operation of UWB technology. After this official permission, research interest has exponentially grown with several researchers exploring RF, circuit, system and antenna designs related to UWB technology.

DESIGN AND ANALYSIS OF VARIOUS CIRCUITS:

I. Compact Tapered-Shape Slot Antenna for UWB Applications

Rezaul Azim and Mohammad Tariqul Islam discussed about a compact micro strip line-fed ultra wideband (UWB) tapered-shape slot antenna. The proposed antenna comprises a tapered-shape slot and rectangular tuning stub. The antenna is fabricated onto an inexpensive FR4 substrate with an overall dimension of 22 X 24 mm.

Figure 6: Schematic diagram of the proposed antenna. (a) Top view. (b) Back view.

Influence of the parameters on antenna performance:

Effect of Tuning Stub-In order to optimize the coupling between the micro strip line and the tapered slot, the rectangular stub was taken which shows a good coupling with the tapered-shape slot, providing a wider impedance matching for UWB applications. Effect of Slot Shape- Introduction of the tapered slot instead of the rectangular slot changes the electric eld distribution by reducing the longest current path and reducing the slot size. It is also observed that high-frequency performance can also be improved by employing tapered slot structure. Effect of Feeding Gap- The gap between the slot and the ground plane determines the matching between the feed line and slot antenna. It is observed that a feed gap of 0.75 mm can give the widest operating band.

ANALYSIS AND RESULT:

The impedance characteristics of the proposed antenna were calculated using the full-wave electromagnetic simulator IE3D. Figure 2 represents measured phase of input impedance.

Figure 7: Measured phase of the input impedance.

Radiation pattern- It can be observed that at the low frequency of 3.4 GHz, the radiation pattern in the XY-plane is omnidirectional with low cross-polarization values.

Figure 8: radiation pattern at 3.4GHz frequency.




The stable radiation pattern with a maximum gain of 5.4 dBi makes the proposed antenna suitable for being used in UWB communication applications.

II. Self-Grounded Bow-Tie Antenna

Jian Yang and Ahmed Kishk discussed novel compact low-profile directional UWB antennathe self-grounded Bow-Tie antenna. The antenna has a simple geometry, ultra-wideband performance with about 10-dB reflection coefficient and stable radiation beams for the frequency range of 215 GHz, and good time-domain impulse response.

Figure 9: Different dimensions used

Figure 9 is showing all the different dimensions used. In this paper the width of the antenna is fixed as 140 mm, and the extended angle has been chosen as 60, 90, and 120, and therefore, the length of the antenna is changed correspondingly. The substrate used is Rogers RO403 board. The radiation pattern is stable having a reflection coefficient of -10db. ANALYSIS AND RESULT:

Figure 10: Simulated reflection coefficients of the three self-grounded Bow-Tie antennas of different extended angles.

The infinite Bow-Tie dipole is a planar scaled structure and therefore is a frequency-independent antenna. In order to have a directional radiation (radiating mainly in one direction), a seagull-over-sea configuration of infinite Bow-Tie antenna is a natural choice, see Figure 10, which is also a scaled structure with the frequency-independent characteristics.

Figure 11: Seagull-over-sea configuration of Bow-Tie.




The new UWB antenna has many unique characteristics: compact size, low profile and at the same time directive radiation function, low reflection coefficient, and good time domain impulse response. It can be foreseen that the self-grounded Bow-Tie antenna will find many applications in UWB communication systems, UWB radar and tracking systems, UWB indoor geolocation systems, UWB sensing and microwave tomography, and more. Further development on this UWB antenna and its applications will be reported in the near future.

III. A CPW-Fed Compact UWB Microstrip Antenna

Anil Kr Gautam, Swati Yadav and Binod Kr Kanaujia proposed a novel coplanar waveguide (CPW)-fed compact ultra wideband (UWB) micro strip antenna for ultra wideband applications. The proposed antenna holds a method to curtail the monopole antenna by loading of inverted L-strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. The prototype with overall size of 25 X 25 X 1.6 mm achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6-13.04 GHz (10.44GHz). This UWB antenna was fabricated and printed on a 1.6-mm-thick FR-4 substrate with permittivity of 4.4 and a loss tangent of 0.024.

Figure 12: Schematic configuration of the proposed compact UWB microstrip antenna.

The inclusion of the two inverted L-shaped strips in the proposed design will significantly improve the impedance-matching conditions for the entire UWB and shows three resonant bands at 3.03, 6.11, and 11.78 GHz. ANALYSIS AND RESULT: The simulated group delay of the proposed antenna is shown in Figure 13. As it can be seen, the variation of the group delay for the proposed antenna is almost constant (remains nearly 1 ns) for the entire UWB band. This confirms that the proposed UWB antenna is suitable for UWB communication.

Figure 13: Group delay for the proposed UWB

Figure 14 shows the measured and simulated 2-D far-field radiation patterns in the H-planes and E-planes at sampling frequencies of 3.03, 6.11, and 11.78 GHz resonance frequencies, respectively. It is found that the antenna has nearly good omnidirectional radiation patterns at all frequencies in the E-plane and the H-plane. This pattern is suitable for application in most wireless communication equipment.




Figure 14: Radiation pattern for various resonance frequencies For the proposed compact UWB microstrip antenna

The good impedance-matching characteristic, constant gain and omnidirectional radiation patterns over the entire operating bandwidth of 2.613.04 GHz (10.44 GHz) make this antenna a good candidate for UWB applications and systems.

IV. A Novel Transparent UWB Antenna for Photovoltaic Solar Panel Integration and RF Energy Harvesting Thomas Peter, Tharek Abd Rahman,S. W. Cheung,Rajagopal Nilavalan,Hattan F. Abutarboush and Antonio Vilches designed a transparent cone top tapered slot antenna covering the frequency range from 2.2 to 12.1 GHz and fabricated to provide UWB communications whilst integrated onto solar panels as well as harvest electromagnetic waves from free space and convert them into electrical energy. The antenna when sandwiched between a-Si solar panel and glass is able to demonstrate a quasi-Omni-directional pattern that is characteristic of a UWB.

Figure 15: (a) Geometry of CTSA and (b) prototype of CTSA




Table 1 DIMENSION (MM) OF THE ANTENNA GEOMETRY IN FIG.

The antenna is first studied laminated on a 2-mm-thick glass, and later sandwiched between the 2-mm-thick glass and an a-Si solar panel. Measurement of solar energy- The measurements are done in the ambient light of fluorescence lighting as well as outdoor in the sun. The solar panel has a conversion rate of more than 15% and is able to deliver a voltage of 5.5 V and a current of 70 mA as per the manufacturers specification in free space.

Measurement of RF energy- A single-tone RF signal is generated using a signal generator and fed to a horn antenna. The rectenna placed at a certain distance is used to collect the RF signal transmitted from the horn and convert it to dc power. The amount of dc converted is used to measure the performance of the rectenna.

ANALYSIS AND RESULT:

The simulated and measured return losses of the CTSA in free space, laminated on the a-Si solar panel and sandwiched between the solar panel and 2-mm glass superstrate are all shown in Figure 16 for comparison.

Figure 16. Simulated and measured return loss of CTSA in free space, on solar panel only, and sandwiched between solar panel and glass The measured radiation patterns in the X-Y direction at two frequencies are depicted in figure 17 .The measured radiation patterns for the sandwich configuration are seen to be quasi-omni directional for different frequencies tested at 3 and 5 GHz.

Figure 17: Radiation pattern at 3 GHz and 5 GHz




In this paper, a novel transparent UWB CTSA that can maintain its Omni- directionality when integrated onto solar panels as well as harvest RF energy, besides being able also to provide wireless communication has been presented. CONCLUSION

In conclusion, the various circuits involving UWB antenna have been observed and their results have been analyzed. The analysis is done by comparison between measured and simulated result of the circuits and by comparing various parameters such as bandwidth, shape, dimension, substrate, radiation pattern etc. In conclusion, the various circuits involving UWB antenna have been observed and their results have been analyzed. The analysis is done by comparison between measured and simulated result of the circuits and by comparing various parameters such as bandwidth, shape, dimension, substrate, radiation pattern etc. On observing various parameters, Self-Grounded Bow-Tie antenna has maximum bandwidth (2-15 GHz). The shape of this antenna is compact and simple and the radiation pattern is also stable (-10db reflection coefficient).This antenna is used in UWB Indoor geolocation system Radar and Tracking system. Hence, the Self Grounded Bow- Tie antenna is most suitable.

REFRENCES

[1] Azim, Rezaul, Mohammad Tariqul Islam, and Norbahiah Misran. "Compact tapered-shape slot antenna for UWB

applications." Antennas and Wireless Propagation Letters, IEEE 10 (2011): 1190-1193. [2] Yang, Jian, and Ahmed Kishk. "A novel low-profile compact directional ultra-wideband antenna: the self-grounded Bow-Tie

antenna." Antennas and Propagation, IEEE Transactions on 60.3 (2012): 1214-1220. [3] Gautam, Anil Kr, Swati Yadav, and Binod Kr Kanaujia. "A CPW-fed compact UWB microstrip antenna." IEEE antennas and

wireless propagation letters 12 (2013): 151-154. [4] Peter, Thomas, et al. "A novel transparent UWB antenna for photovoltaic solar panel integration and RF energy

harvesting." Antennas and Propagation, IEEE Transactions on 62.4 (2014): 1844-1853. [5] Schantz, Hans Gregory. "Introduction to ultra-wideband antennas." IEEE conference on ultra wideband systems and

technologies. Vol. 2993. 2003. [6] Balanis, Constantine A. Antenna theory: analysis and design. John Wiley & Sons, 2012. [7] Schantz, Hans Gregory. "A brief history of UWB antennas." IEEE Aerospace and Electronic Systems Magazine 19.4 (2004):

22-26. [8] Barrett, Terence W. "Technical features, history of ultra wideband communications and radar: part I, UWB

communications." Microw J 44.1 (2001): 22-56.

PARAMETERS Compact Tapered Shape Slot Antenna

Self-Grounded Bow Tie Antenna

CPW fed Compact UWB Antenna

Novel transparent UWB Antenna (for solar panel)

BANDWIDTH 3-11.2 GHz 2-15 GHz 2.6 -13.04 GHz

2.2-12.1 GHz

SHAPE Tapered shape slot Rectangular stub

Novel low profile , Compact and simple geometry

Noval coplanar -

DIMENSION 22*24 mm2 Thickness-1.6mm

L= 58mm (=60 0) L=100mm (=900) L=166mm (=1200mm)

25*25*16mm3

Thickness=2mm Overall size 17*33.5mm2

SUBSTRATE FR4 r = 4.50 tan=0.0180

Rogers RO403 board r =3.38 Tan=0.027

FR-4 r = 4.4 Tan=0.02

AgHT-4

study and performance analysis of uwb antenna for uwb ccommunication systems

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