Corner truncated inverted u   slot triple band tunable rectangular microstrip antenna for wlan applications
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Corner truncated inverted u slot triple band tunable rectangular microstrip antenna for wlan applications

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    Corner truncated inverted u   slot triple band tunable rectangular microstrip antenna for wlan applications Corner truncated inverted u slot triple band tunable rectangular microstrip antenna for wlan applications Document Transcript

    • INTERNATIONAL JOURNAL OF ELECTRONICS ANDInternational Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)ISSN 0976 – 6464(Print)ISSN 0976 – 6472(Online)Volume 3, Issue 1, January- June (2012), pp. 01-09 IJECET© IAEME: www.iaeme.com/ijecet.htmlJournal Impact Factor (2011)- 0.8500 (Calculated by GISI) ©IAEMEwww.jifactor.com CORNER TRUNCATED INVERTED U - SLOT TRIPLE BANDTUNABLE RECTANGULAR MICROSTRIP ANTENNA FOR WLAN APPLICATIONS Nagraj Kulkarni1 and S. N. Mulgi2 Department of PG Studies and Research in Applied Electronics, Gulbarga University, Gulbarga-585106, Karnataka, India Email: 1nag_kulb@rediffmail.com 2 s.mulgi@rediffmail.comABSTRACTThis paper presents the design and development of simple corner truncated rectangularmicrostrip antenna comprising inverted U-slot on the radiating patch for triple band andtunable operation. The proposed antenna is excited through microstripline. The low costglass epoxy substrate material is used to fabricate the antenna. The antenna operatesbetween 4.74 to 9.59 GHz for three frequency bands and gives broadside radiationcharacteristics. The tuning of secondary bands can be achieved by varying the width ofinverted U-slot. The experimental and simulated results are in good agreement with eachother. The proposed antenna may find applications in WLAN.Key words: Corner truncated, microstrip antenna, triple band, tuning.1. INTRODUCTIONMicrostrip antennas are becoming increasingly popular because of their small size,lightweight, low cost, easy to fabricate and compatible to microwave integrated circuits[1-2]. However, the modern communication systems such as wireless local area networks(WLAN) often require antennas possessing two or more discrete frequency bands, whichcan avoid the use of multiple antennas. The multiband microstrip antennas are designedby cutting slots of different geometries like bow-tie, rectangular, square ring, annular ringetc. on the radiating patch [3-6]. The tuning of the bands is achieved by incorporatingshorting pins, open and closed stubs, shorting posts and use of active devices withvariable biasing voltages [7-12] etc. But the multiband operation and tuning of the 1
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEMEoperating bands using planar corner truncated inverted U-slot rectangular microstripantenna is found to be rare in the literature.2. DESIGNING OF ANTENNAThe conventional rectangular microstrip antenna (CRMSA) and corner truncated invertedU-slot rectangular microstrip antenna (CTIUSRMSA) are fabricated on low cost glassepoxy substrate material of thickness h = 1.6 mm and dielectric constant εr = 4.2. Theartwork of CRMSA and CTIUSRMSA is developed using computer software AUTOCAD to achieve better accuracy. The antennas are etched by photolithography process.The bottom surface of the substrate consists of a tight ground plane copper shielding.Figure 1 shows the top view geometry of CRMSA. This antenna is designed for theresonant frequency of 3.5 GHz using the equations available in the literature for thedesign of rectangular microstrip antenna on the substrate area A x B [13]. This antennaconsists of a radiating patch of length L and width W. A quarter wave transformer oflength Lt and width Wt is incorporated to match the impedances between CP andmicrostripline feed of length Lf and width Wf. A 50 semi miniature-A (SMA)connector is used at the tip of the microstripline to feed the microwave power.Figure 2 shows the top view geometry CTIUSRMSA which is constructed from CRMSA.Two diagonally opposite corners of CRMSA are truncated as Xd and Yd. The novelinverted U slot is placed at the center of the rectangular radiating patch. Lh and Lv arethe lengths of horizontal and vertical arms of inverted U slot respectively. Thedimensions Lh and Lv are taken in terms of λ0, where λ0 is a free space wave length in cmcorresponding to the designed frequency of 3.5 GHz. Uw is the width of the horizontaland vertical arms of inverted U slot. The inverted U-slot is placed at a distance of 0.305cm from radiating (W) and 0.415 cm from non-radiating (L) edges of the rectangularpatch respectively. The various parameters of the proposed antennas are listed as in Table1. Figure 3 (a) and (b) show the 3D view of CRMSA and CTIUSRMSA respectively.3. EXPERIMENTAL RESULTSThe German make (Rohde and Schwarz, ZVK model 1127.8651) Vector NetworkAnalyzer is used to measure the experimental return loss of CRMSA and CTIUSRMSA.The simulation of the CRMSA and CTIUSRMSA is carried out using High FrequencyStructure Simulator (HFSS) software.Figure 4 shows the variation of return loss versus frequency of CRMSA. From this figureit is clear that, the CRMSA resonates at 3.39 GHz of frequency which is close to thedesigned frequency of 3.5 GHz. The experimental impedance bandwidth over return lossless than -10dB is calculated using the formula,  (f − f )  Impedance Bandwidth (%) =  2 1  ×100 %  fc  2
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEMEwhere, f2 and f1 are the upper and lower cut off frequencies of the resonating band whenits return loss reaches -10 dB and fc is a centre frequency between f1 and f2. Theimpedance bandwidth of CRMSA is found to be 3.27 %. The simulated result of CRMSAis also shown in Fig. 4.Figure 5 shows the variation of return loss versus frequency of CTIUSRMSA. It is clearfrom this figure that, the antenna operates for three bands BW1 (4.67-4.82 GHz), BW2(5.74-6.01 GHz) and BW3 (8.79-9.74 GHz) for the resonating modes of f1, f2 and f3respectively, when Uw = 0.2 cm. The three bands BW1, BW2 and BW3 are due to theindependent resonance of patch, corner truncated slots and inverted U-slot ofCTIUSRMSA. The BW1 is considered as primary band because its resonating mode f1remains close to fr of CRMSA. The BW2 and BW3 are considered as secondary bands. Itis observed from Fig. 5 that, the construction of CTIUSRMSA does not affect much theresonant mode of primary band i.e. f1, but two additional resonating modes appear at f2and f3. The simulated result of CTIUSRMSA is also shown in Fig. 5 which is in goodagreement with the experimental results. The magnitude of impedance bandwidth ofBW1, BW2 and BW3 are found to be 3.16%, 4.5% and 10.2% respectively. Thefrequency ratio f2/f1 of CTIUSRMSA is found to be 1.242.Figure 6 shows the variation of return loss versus frequency of CTIUSRMSA. It is seenfrom this figure that, the antenna operates for three bands BW4 (4.73-4.91 GHz), BW5(7.48-7.92 GHz) and BW6 (8.93-10.24 GHz) for the resonating modes of f4, f5 and f6respectively, when Uw is increased from 0.2 to 0.3 cm. It is clear from this figure that,the resonating modes f5 and f6 are shifted towards higher frequency side when comparedto f2 and f3 respectively, without much shift in the primary resonant mode i.e. f1. Thischange in the resonating modes of antenna is due to the increase of Uw from 0.2 to 0.3cm. The simulated result of CTIUSRMSA is also shown in Fig. 6 which is in goodagreement with the experimental results. The magnitude of impedance bandwidth ofBW4, BW5 and BW6 are found to be 3.73%, 5.71% and 13.55% respectively. Thefrequency ratio f5/f4 of CTIUSRMSA is found to be 1.59 indicates shifting of secondaryresonant mode f5 with respect to primary resonant mode f4 . The gain of the proposed antennas is measured by absolute gain method. Thepower transmitted ‘Pt’ by pyramidal horn antenna and power received ‘Pr’ by antennaunder test (AUT) are measured independently. With the help of these experimental data,the gain (G) dB of AUT is calculated by using the equation, P   λ  (G) dB=10 log  r  - (G t ) dB - 20log  0  dB  Pt   4πR where, Gt is the gain of the pyramidal horn antenna and R is the distance between thetransmitting antenna and the AUT. The maximum gain CTIUSRMSA measured in BW1and BW4 are found to be 1.21dB, 1.64 dB respectively.Figure 7-9 show the co-polar and cross-polar radiation pattern of CRMSA andCTIUSRMSA measured in their operating bands. From these figures it is clear that, thepatterns are broadsided and linearly polarized. 3
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME4. CONCLUSION From the detailed experimental study, it is concluded that, the CRMSA can bemade to operate at three frequency bands between 4.74 to 9.59 GHz by loading invertedU-slot on the radiating patch. The secondary bands of CTIUSRMSA can be tuned tohigher side of the frequency spectrum by increasing the width of horizontal and verticalarms of inverted U-slot without affecting much the primary band. Tuning of triple bandsdoes not affect the nature of broadside radiation characteristics. The proposed antennasare simple in their geometry and are fabricated using low cost glass epoxy substratematerial. The CTIUSRMSA may find applications in wireless local areanetwork(WLAN).ACKNOWLEDGMENTS The authors would like to thank the authorities of Dept. of Science. &Technology. (DST), Govt. of India, New Delhi, for sanctioning the Vector NetworkAnalyzer under the FIST project to the Department of Applied Electronics, GulbargaUniversity, Gulbarga.REFRENCES 1. Kin-Lu Wong, Compact and Broad band microstrip Antennas, A Wiley-Inter Science Publication, John Wiley & Sons. Inc. 2. Garg Ramesh , Bhatia Prakesh, Bahl Inder and Boon Apisakittir (2001), Microstrip Antennas Design Hand Book, Artech House Inc. 3. Behera. S and Vinoy. K. J, “Microstrip square ring antenna for dual band operation,” Progress In Electromagnetics Research, PIER 93, 41–56, 2009. 4. Roy . J. S, Chattoraj, and N. Swain, “ short circuited microstrip antenna for multi-band wireless communications,” Microwave and Optical Technology Letters, Vol .48, 2372-2375, 2006. 5. Sadat, S , M. Fardis F. Geran, and G. Dadashzadeh,” A compact microstrip square-ring slot antenna for UWB applications,” Progress In Electromagnetic Research PIER 67, 173-179, 2007. 6. Shams. K. M Z , M. Ali, and H. S. Hwang, “A planar inductively coupled bow-tie slot antenna for WLAN application,” Journal of Electromagnetic Waves and Applications, Vol.20, 86-871, 2006. 7. Kuo, J. S and K. L. Wong, “A compact microstrip antenna with meandered slots in the ground plane,” Microwave and Optical Technology Letters, Vol. 29, 95-97, April 2001. 8. Sharma A. and G. Singh, “Design of single pin shorted Three – dielectric layered substrates rectangular patch microstrip antenna for communication system,” Progress In Electromagnetic Research PIER 2. 157 – 165, 2008. 9. Ang. B. K and B.K Chung,“A wideband microstrip patch antenna for 5-6 GHz Wireless communication,” Progress In Electromagnetic Research PIER 75, 397-407, 2007. 4
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME 10. Eldek .A. A, A .Z. Elsherbeni and C.E. Smith, “Characteristics of bow-tie slot antenna with tapered tuning stubs for wideband operation,” Progress In Electromagnetic Research PIER 49, 53 – 69, 2004. 11. Waterhouse R.B, “Broadband stacked shorted patch” Electronic Letters, Vol.35, 98-100, Jan. 1999. 12. Ge,Y, K. P. Esselle and T. S. Bird, “A broadband E-shaped patch antenna with a microstrip compatible feed,” Microwave and Optical Technology Letters, Vol .42, No. 2, July 2004. 13. Bahl, I. J and P. Bhartia, Microstrip Antennas, Artech house, New Delhi, 1980. Table 1 Design Parameters of CRMSA and CTIUSRMSA Antenna Dimensions Antenna Dimensions Parameters in cm Parameters in cm W 2.66 Lh λ0/85 Wf 0.32 Lv λ0/42 Wt 0.06 Xd 0.8 L 2.04 Yd 0.2 Lf 2.18 A 5 Lt 1.09 B 8 5
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME Figure 1 Top view geometry of CRMSA Figure 2 Top view geometry of CTIUSRMSA 6
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME Figure 3(a) 3d view of CRMSA Figure 3(b) 3D view of CTIUSRMSA Figure 4 Variation of return loss versus frequency of CRMSA 7
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEMEFigure 5 Variation of return loss versus frequency of CTIUSRMSA when Uw = 0.2 cm Figure 6 Variation of return loss versus frequency of CTIUSRMSA when Uw = 0.3 cm Figure 7 Radiation pattern of CRMSA measured at 3.39 GHz 8
    • International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976– 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME Figure 8 Radiation pattern of CTIUSRMSA when Uw = 0.2 cm measured at 4.74 GHz Figure 9 Radiation pattern of CTIUSRMSA when Uw = 0.3 cm measured at 4.82GHz 9