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A SMALL CPW-FED ULTRA WIDEBAND ANTENNA WITH DUAL BAND-NOTCHED CHARACTERISTICS

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A SMALL CPW-FED ULTRA WIDEBAND ANTENNA WITH DUAL BAND-NOTCHED CHARACTERISTICS
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   ACKNOWLEDGMENTS This work is supported by the Science Fund of China (60801033),the State Key Laboratory of Millimeter Waves (K201112) and theFundamental Research Funds for the Central Universities(2011IM0025). REFERENCES 1. S.F.R. Chang, W.L. Chen, S.C. Chang, C.K. Tu, C.L. Wei, C.H.Chien, C.H. Tsai, J. Chen, and A. Chen, A dual-band RF transceiver for multi-standard WLAN applications, IEEE Trans MicrowaveTheory Tech 53 (2005), 1048–1055.2. L.C. Tsai and C.W. Hsue, Dual-band bandpass filters using equal-length coupled-serial-shunted lines and Z-transform technique, IEEETrans Microwave Theory Tech 52 (2004), 1111–1117.3. C.Y. Chen and C.Y. Hsu, A simple and effective method for micro-strip dual-band filters design, IEEE Microwave Wireless ComponLett 16 (2006), 246–248.4. Q.X. Chu and F.C. Chen, A compact dual-band bandpass filter usingmeandering stepped impedance resonators, IEEE Microwave Wire-less Compon Lett 18 (2008), 320–322.5. J.T. Kuo, T.H. Yeh, and C.C. Yeh, Design of microstrip bandpassfilters with a dual-passband response, IEEE Trans MicrowaveTheory Tech 53 (2005), 1331–1337.6. X.Y. Zhang, and Q. Xue, Novel centrally loaded resonators andtheir applications to bandpass filters, IEEE Trans Microwave TheoryTech 56 (2008), 913–921.7. M.Q. Zhou, X.H. Tang, and F. Xiao, Compact dual bandbandpass filter using novel E-type resonators with controllable band-widths, IEEE Microwave Wireless Compon Lett 18 (2008),779–781.8. X.Y. Zhang, C.H. Chan, Q. Xue, and B.J. Hu, Dual-bandbandpass filter with controllable bandwidths using twocoupling paths, IEEE Microwave Wireless Compon Lett 20 (2010),616–618.9. F.C. Chen and Q.X. Chu, Novel multistub loaded resonator and itsapplication to high-order dual-band filters, IEEE Trans MicrowaveTheory Tech 58 (2010), 1551–1556.10. C.K. Liao, P.L. Chi, and C.Y. Chang, Microstrip realization of gen-eralized Chebyshev filters with box-like coupling schemes, IEEETrans Microwave Theory Tech 55 (2007), 147–153.11. J.S. Hong and M.J. Lancaster, Microstrip filter for RF/microwaveapplications, Wiley, New York, 2001. V C 2012 Wiley Periodicals, Inc.  A SMALL CPW-FED ULTRA WIDEBAND ANTENNA WITH DUAL BAND-NOTCHEDCHARACTERISTICS M. Moosazadeh 1 and Z. Esmati 2 1 Department of Electrical Engineering, Science and ResearchBranch, Islamic Azad University, Tehran, Iran; Correspondingauthor: mahdimoosazadeh59@yahoo.com 2 Department of Electrical Engineering, Islamic Azad University,Urmia Branch, Urmia, Iran  Received 28 August 2011 ABSTRACT:  A coplanar waveguide fed (CPW-fed) ultra wideband (UWB) antenna with dual band- notched characteristics is proposed. Inthis antenna, an E-shaped patch and a ground plane truncated with twomirror notches are designed for UWB applications. Two notched  frequency bands are achieved by adjusting the E-shaped form lengths inthe radiation patch. The proposed antenna operates in the 3.1–10.6 GHz for a voltage standing-wave ratio (VSWR) less than 2, except two frequency notched bands of 3.3–4.23 and 5.05–5.87 GHz, and has smalloverall dimensions of 18    15    1.6 mm3. Experimental and simulated antenna results show that the proposed antenna has a desirable VSWRlevel and radiation pattern characteristics for the UWB frequency band range. V C 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett54:1528–1532, 2012; View this article online at wileyonlinelibrary.com.DOI 10.1002/mop.26847 Key words:  ultra wideband antenna; microstrip line-fed; monopoleantenna; frequency band-notch function; truncated ground plane 1. INTRODUCTION Quick development of wireless communication in the field of ultra wideband (UWB) technology and its applications hasincreased demand in commerce and industry. There has beengreat progress in the design of UWB antennas and devices inrecent years. In 2002, the U.S. Federal Communication Commis-sion approved the frequency range from 3.1 to 10.6 GHz for usein UWB communication systems [1]. One of the major challengesin the design of UWB antennas is how to achieve small sizeantennas with low cost, low weight, and desired radiation patterncharacteristics and electrical properties in the band of interest. Inthe design of a UWB planar monopole antenna, the shape of theantenna patch, the ground plane, and the geometry of the ground Figure 1  Configuration of the proposed antenna with E-shaped formon the patch. (a) Dimensions and parameters of the proposed antenna(unit: mm). (b) Photograph of the printed monopole antenna (front).[Color figure can be viewed in the online issue, which is available atwileyonlinelibrary.com] 1528  MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 54, No. 6, June 2012 DOI 10.1002/mop  plane slots are of great importance [2, 3]. Different methods suchas the truncated slot on the antenna patch have been proposed for increasing impedance bandwidth [4–6]. However, there are sev-eral existing bands operating in the same UWB frequency bandsuch as the IEEE802.11a WLAN system operating in 5.15–5.825GHz, the IEEE802.16 WiMAX system operating in 3.3–3.6GHzand C-band satellite communication system in 3.7–4.2 GHz.Recently, several antennas with band-stop characteristics havebeen reported. In most reported antennas, up to now, the slots onthe radiation patch or ground plane have been used for achievingband-notched characteristics [7–13].In this article, a CPW-fed UWB antenna with dual band-notch characteristics with increased bandwidth is presented. Toimprove the bandwidth, two notches are located on the groundplane. Two notched frequency bands are obtained by using E-shaped form in the radiation patch. In the present antennadesign, wider impedance bandwidth can be achieved with twonotches in the ground plane. The antenna has a compact size of 18 mm    15 mm    1.6 mm. Details of the antenna design arepresented, and comparison between simulated and measuredresults of voltage standing-wave ratio (VSWR), and radiationpatterns and antenna gain are given. 2. MONOPOLE ANTENNA DESIGN Figure 1 shows the geometry of the proposed antenna with  W  sub   L sub  dimensions. The antenna is constructed with a substratemade of FR4, with the thickness of 1.6 mm and the relativedielectric constant 4.4. The CPW feed is designed with fixed 3mm feed line widths and 0.3-mm ground gap for 50- X  charac-teristic impedance. The constructed antenna consists of a semi-rectangular patch and rectangular ground plane. A rectangular patch with E-shaped form is connected to the CPW groundplane to act as a filter structure. By adjusting the length andwidth of the E-shaped form the band-notched characteristics for WiMAX, the C-band satellite communication systems, andWLAN can be obtained. For the impedance matching, the dis-tance between the patch and the ground plane is indicated witha gap. In addition, for increasing the upper frequency band andimproving impedance matching, a pair of rectangular notches islocated on the CPW ground plane. A truncated ground planeplays a major role in broad band characteristics of this antenna, Figure 2  (a) Antenna without notch with ground plane. (b) Antenna with two rectangular notches in the ground plane Figure 3  Simulated VSWR for antenna shown in Figure 2 Figure 4  Simulated current distribution of the dual band-notched monop-ole antenna. (a) First notch frequency and (b) Second notch frequency DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 54, No. 6, June 2012  1529  which helps to proper matching the patch and the ground plane.The optimal parameters of the constructed antenna are as fol-lows:  W  sub  ¼  18,  L Sub  ¼  15,  W  E1  ¼  7,  W  E2  ¼  8.75,  L E1  ¼  0.5,  L E2  ¼  2.5,  g c  ¼  0.3,  W  c  ¼  3,  X  E  ¼  4,  W  E  ¼  7.75, and gap  ¼  1mm. 3. SIMULATION AND MEASUREMENT RESULT In this section, after introducing the proposed antenna, we inves-tigate the various values of   W  E ,  W  E2 ,  L E2 , and  X  E  parameters.The simulated results are obtained using the Ansoft simulationsoftware high-frequency structure simulator (HFSS 10) [14].Figure 2 shows the different between the antenna structure andthe ground planes. In the proposed antenna without notch on theground plane, the impedance matching is poor at the frequencyband over 5.5 GHZ. As shown in Figure 3, by using a pair of mirror rectangular notches on the ground plane, a proper imped-ance matching on the upper frequency band can be achieved.Figure 4 shows the current distribution at the first and secondnotch frequency. As shown in Figures 4(a) and 4(b), in thesestructures at the notch frequency, the current flows are moredominant around the filter .pb4 structures. The first notched Figure 5  Simulated band-rejection characteristics of the proposedantenna with notched bands for various values  X  E Figure 6  Simulated band-rejection characteristics of the proposedantenna with notched bands for various values  W  E Figure 7  Simulated band-rejection characteristics of the proposedantenna with notched bands for various values  W  E2  and  L E2 Figure 8  Comparison between measured and simulated VSWR for the proposed antenna Figure 9  Measured antenna gain of the proposed antenna 1530  MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 54, No. 6, June 2012 DOI 10.1002/mop  band corresponds to the length of the  X  E . Figure 5 shows thesimulated VSWR of the proposed antenna with various values  X  E . It can be observed that by increasing  X  E  from 0 to 6 mm,the notched band moves to a lower frequency. Also, it can beobserved that by changing the length of the  X  E , suitable band-notch characteristic can be achieved. Therefore, doing severalexperiments,  X  E  in 4 mm is fixed. Figure 6 shows the effects of  W  E  variation on the band-notched characteristics. As shown inFigure 6, the central frequency of band notch at 5.5 GHzdecreased by increasing the value of   W  E . Figure 7 shows thesimulated VSWR curves with various values for   W  E2  and  L E2 . Itcan be observed that by increasing the width of the  W  E2  andlength of the  L E2 , suitable dual band-notched and their notchedbandwidths can be controlled. All of the results certify that theantenna is a promising candidate for UWB system to avoidinterference with WiMAX (3.3–3.6), C-band (3.7–4.2), andWLAN (5.15–5.825) bands. The impedance bandwidth withdual band-notched characteristics was tested by using an Agilent8722ES Vector Network Analyzer, as indicated in Figure 8. TheFigure clearly shows that the impedance bandwidth of proposedantenna very well covers the intended VSWR  <  2 and has dualband-notched characteristics (VSWR  >  2) in 3.3–4.23 GHz and5.05–5.87 GHz. As shown in Figure 8, the good agreementbetween the simulated and measured results is observed. Also, Figure 10  Measured radiation pattern of the proposed antenna. (a) 4.5 (b) 8, and (c) 11 GHz DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 54, No. 6, June 2012  1531  by using this filter structures, the lowest frequency is signifi-cantly decreased from 3.65 to 2.8 GHz. Figure 9 shows themeasured antenna gain from 3 to 11 GHz for the proposedantenna with the filter structure. The Figure indicates that therealized dual band-notched antenna has good gain flatnessexcept in the two notched bands. As shown in Figure 9, gaindecreases drastically at the frequency bands of 3.5 and 5.5 GHz.Figure 10 shows the measured radiation pattern in frequencies4.5, 8, and 11 GHz of the UWB band in  H  -plane (  xz  plane) and  E -plane (  yz  plane). From an overall view of these radiation pat-terns, the designed antenna behaves quite similarly to the typicalprinted monopoles in the lower and middle frequency bands.The Figure is approximately indicative of omnidirectional radia-tion pattern in  x  –  z  plane. 4. CONCLUSION In this article, a novel CPW-fed antenna with dual band-notchfunction is proposed for UWB applications. Dual stop-band isachieved using an E-shaped form on the radiation patch. Thenotched band can be controlled by adjusting the filter structureson the patch, which exempt from interfaces with existingWiMAX, WLAN, and C operating bands. By inserting twonotches in the corners on the ground plane with proper dimen-sions, a wide impedance bandwidth is achieved. This antennawith two controllable notched bands is suitable for UWB sys-tems with proper dimensions and aforementioned characteristics. REFERENCES 1. H. Schantz, The art and science of UWB antennas, Artech House,Norwood, MA, 2005.2. Q. Wu, R. Jin, J. Geng, and M. Ding, Printed omni-directionalUWB monopole antenna with very compact size, IEEE TransAntennas Propag 56 (2008), 896–899.3. M. Moosazadeh, C. Ghobadi, and Z. Esmati, Monopole antennabased on wrench-shaped slot on circular disc patch for UWB appli-cation, Microwave Opt Technol Lett 53 (2011), 1927–1931.4. M. Ojaroudi, C. Gobadi, and J. Nourinia, Small square monopoleantenna with inverted T-shaped notch in the ground plane for ultra-wideband (UWB) application, IEEE Antennas Wireless Propag Lett8 (2009), 728–731.5. K.G. Thomas and M. Sreenivasan, Printed elliptical monopole withshaped ground plane for pattern stability, Electron Lett 45 (2009),445–446.6. M. Moosazadeh, C. Ghobadi, and M. Dousti, Small monopoleantenna with checkered- shaped patch for UWB application, IEEEAntennas Wireless Propag Lett 9 (2010), 1014–1017.7. R. Gayathri, T.U. Jisney, D.D. Krishna, M. Gopikrishna, andC.K. Aanandan, Band- notched inverted-cone monopole antennafor compact UWB systems, Electron Lett 44 (2008),1170–1171.8. M.A. Antoniades and G.V. Eleftheriades, A compact multibandmonopole antenna with a defected ground plane, IEEE AntennasWireless Propag Lett 7 (2008), 652–655.9. K. Bahadori and Y. Rahmat-Samii, A miniaturized elliptic-cardUWB antenna with WLAN band rejection for wireless communica-tions, IEEE Trans Antennas Propag 55 (2007), 3326–3332.10. C.-Y. Hong, C.-W. Ling, I.-Y. Tarn, and S.-J. Chung, Design of aplanar ultrawideband antenna with a new band-notched structure,IEEE Trans Antennas Propag 55 (2007), 3391–3397.11. K. Chung, S. Hong, and J. Choi, Ultrawide-band printed monopoleantenna with band-notch filters, Microwave Antennas Propag 1(2007), 518–522.12. L.-N. Zhang, S.-S. Zhong, X.-L. Liang, and C.-Z. Du, Compactomnidirectional band-notch ultra-wideband antenna, Electron Lett45 (2009), 659–660.13. M. Ojaroudi, G. Ghanbari, N. Ojaroudi, and C. Ghobadi, Smallsquare monopole antenna for UWB applications with variable fre-quency band-notch function, IEEE Antennas Wireless Propag Lett 8(2009), 1061–1064.14. Ansoft Corp., Ansoft high frequency structure simulation (HFSS).ver. 10, Ansoft Corp, Pittsburgh, PA, 2005. V C 2012 Wiley Periodicals, Inc. STUDY OF A NOVEL U-SHAPEDMONOPOLE UWB ANTENNA BY TRANSFER FUNCTION AND TIMEDOMAIN CHARACTERISTICS G. P. Gao, 1,2 M. K. Yang, 1 S. F. Niu, 1 and J. S. Zhang 1 1 School of Information Science and Engineering, LanzhouUniversity, Rom 404, Fei Yun Lou, 222 Tian Shui Road, Lanzhou,730000, People’s Republic of China; Corresponding author:gaoguoping-1983@163.com 2 State Key Laboratory of Millimeter Waves, Southeast University,Nanjing 210096, People’s Republic of China  Received 17 August 2011 ABSTRACT:  A novel U-shaped monopole antenna suitable for ultrawideband (UWB) application is presented and investigated in thisarticle. The antenna is developed from printed circular disc monopoleantenna, and the current distribution evident that the proposed antennahas a similar current. Three steps in ground plane is designed and adjusted to obtain UWB impedance matching. Experimental results show Figure 1  Geometry of the U-shaped monopole UWB antenna, (a) geometry and (b) photograph. [Color figure can be viewed in the online issue,which is available at wileyonlinelibrary.com] 1532  MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 54, No. 6, June 2012 DOI 10.1002/mop
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