A COMPACT MODIFIED DISC MONOPOLE ANTENNA FOR SUPER-WIDEBAND APPLICATIONS WITH ENHANCED GAIN

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1 Proceeding of NCRIET-215 & Indian J.Sci.Res. 12(1):37-311, 215 ISSN: (Print) ISSN: (Online) A COMPACT MODIFIED DISC MONOPOLE ANTENNA FOR SUPER-WIDEBAND APPLICATIONS WITH ENHANCED GAIN BOYA SATYANARAYANA a1, S.N. MULGI b AND P.V. HUNAGUND c abc Department of P.G. Studies and Research in Applied Electronics, Gulbarga University, Kalaburagi, India ABSTRACT A compact planar printed monopole antenna for super-wideband (SWB) application is presented. Simple technique has been used by modifying the circular disc to arch shape and by embedding the rectangular slots into a partially truncated ground plane the super-wideband is achieved. The proposed antenna has a compact size in its structure compared to conventional antenna designed for the same frequency. The proposed antenna uses an area of mm 2 fed by microstrip line and gives an impedance bandwidth of 189% ( GHz) with bandwidth ratio is more than 34.5:1 for S 11 < -1 db and exhibits an omni directional radiation characteristics over the entire frequency band and with an enhanced gain. The design of proposed antenna and its various parameters are studied by using the An soft High Frequency Structural Simulation (HFSS) software. This antenna may cover mobile communication services such as Bluetooth (2.8 GHz) WIMAX (3.4 GHz), WLAN (2.4/5 GHz), UMTS and Ultra-wideband (UWB)( GHz) applications. KEYWORDS: Monopole Antenna, Super-Wideband, Enhanced Gain, Ultra-Wideband (UWB), WiMAX, WLAN Nowadays, the planar structure monopole antennas are most widely used and extensively studied for Ultra-wideband (UWB) communication system applications because of their useful features, such as low profile, less weight, easily fabricated, integration with other MMIC devices and omni-directional radiation characteristics. In the year 22, the Federal Communications Commission (FCC) of United States was assigned frequency band from 3.1 to 1.6 GHz for the ultra-wideband (UWB) technology (Commission 22). Since then the UWB communication technology has receiving many advantages such as short range high secured data transmission, low power consumption, easily accessible system structure and avoiding of interference signals of other wireless frequency bands. Hence, the UWB communication technology has becoming a worldwide wireless technology for handheld high-tech gadgets. In recent years, the various types UWB monopole antenna configurations such as rectangular, square, elliptical, circular disc, head shaped with omni-directional radiation patterns for present and future UWB applications within the 3.1 to 1.6 GHz frequency range have been designed and studied and their characteristics has been installed in many wireless handheld devices(jung, Choi, and Choi 25)(Azenui and Yang 27)(Choi, 24)(J. Liang, 24)(J. Liang, 25). Some monopole antenna designs such as rectangular shape, Semielliptical, circular, egg-shaped and elliptical monopole antennas with impedance bandwidth ratio more than 1:1is achieved and such an antennas are commonly known as super-wideband (SWB) antennas and these are reported in (C. Deng, 29)(X. R. Yan, 27)(Hsia, 25)(K. R. Chen, 211)(Z. N. Chen, 27). In this paper, a compact printed modified disc SWB monopole antenna (also covering UWB frequency band) fed by a microstripline is presented. By modifying the circular radiating patch and embedding the wide rectangular slots into the asymmetrical truncated ground plane, the antenna is capable to work from.68 to GHz with bandwidth ratio of 34.5:1 for below -1 db. The performance of the antenna and optimized antenna design is analyzed using Ansoft HFSS tool (Ansoft Corporation, 28)and the obtained results are discussed. ANTENNA DESIGN The optimized design of the proposed SWB monopole antenna is as shown in Fig. 1. This antenna is printed on a 1.6 mm thick modified glass epoxy dielectric substrate of permittivity (ε r ) 4.2 and loss tangent (δ).2 with size of 34 mm 36 mm. The antenna is formed from the conventional circular radiating patch and is fed by simple 5Ω microstripline and this feedline is connected to 5Ω- SMA connector for excitation. For the performance of 1 Corresponding author

2 impedance matching that results in impedance bandwidth enhancement, the simple technique has been adopted and a rectangular notch is created at the feeding position on bottom. An asymmetric partial ground plane of 2 mm 15 mm is used. To permit the SWB antenna to operate in much lower frequency of less than 1 GHz, wide rectangular slots are embedded at the middle of the ground plane and the gap (g) between radiating patch and the ground plane is maintained at.7 mm. The microstripline feed width (W f ) is fixed at 3.17 mm to achieve 5Ω characteristic impedance. The optimized design parameters of the prosed SWB antenna are as follow: W = 34 mm, L= 36 mm, S 1 & S 2 = 1 mm, W f = 3.17 mm, L f = 15.4 mm, L g = 15 mm, R= 7.9 mm and g =.7 mm, W 1 &W 2 = 4 mm, L 1 & L 2 = 8.25 mm, L = 2.4 mm and W = 3.2 mm. Telecommunication System (UMTS), Wireless Local area Network (WLAN) and ultra-wideband UWB system applications m R e tu r n L o s s [d B ] Frequency XY Versus Plot 3 Return Loss m Figure 2: Return loss versus frequency plot of the proposed SWB antenna db(s(lumpport1,lumpport1)) VSWR XY Plot Plot VSWR(LumpPort1) V S W R (L u m p P o rt1 ) Freq [GHz] Figure 3: The VSWR plot of the proposed SWB antenna XY Plot 5 im(z(lumpport1,lumpport1)) re(z(lumpport1,lumpport1)) 5... Figure 1: Geometry of the proposed SWB antenna RESULTS AND DISCUSSION Y The proposed SWB antenna is simulated with 3D full-wave electromagnetic Ansoft HFSS software. The simulated return loss versus frequency and VSWR plots for the optimized design parameters are as shown in Figure 2 and 3 respectively. From these figures, the antenna meet the expectations of the magnitude of the return loss is less than -1dB ( S 11 < -1 db) and the simulated VSWR 2which gives a impedance bandwidth of 189% covers the frequency range from.68 to GHZ with good ratio impedance bandwidth of 34.5:1 is calculated. Therefore, the proposed SWB antenna can cover the Bluetooth, Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile Figure 4: The simulated input impedance Z in versus frequency plot for the proposed SWB antenna Figure 4 shows the simulated input impedance Z in of the proposed SWB antenna. From this figure it is clear that, the imaginary and real parts of the input impedance are maintained as 5 Ω and Ω respectively throughout the entire operating frequency band. It is also clear from the imaginary component of the input impedance Z in that major part

3 of the operating frequency band showing good impedance matching. Figure 5(a)-(d) shows the simulated surface current and distributions for the minimum return loss ( S 11 ) of the proposed antenna at frequencies 1.41, 8.89, and 2.22 GHz respectively. From these figures, it can observe that, the density of current is mainly distributed near along the edges of the ground plane, while on the top surface the currents are primarily concentrated on microstripline feed and lower outer edges of the disc. (d) Figure 5: Simulated current distributions (in A/m) at (a) 1.41, (b) 8.89, (c) and (d) 2.22 GHz Radiation Pattern Freq='3.1125GHz' Phi='deg' Freq='3.1125GHz' Phi='9deg' (a) (b) (a) Radiation Pattern Freq='5.5225GHz' Phi='deg' Freq='5.5225GHz' Phi='9deg' (c)

4 (b) Radiation Pattern Freq='9.9325GHz' Phi='deg' Freq='9.9325GHz' Phi='9deg' (d) Figure 6: 2D and 3D E-plane (X-Y plane) and H- plane (X-Z) radiation patterns measured at (a) 3 GHz, (b) 5.2 GHz and (c) 9.9 GHz and GHz XY Plot 8 db(peakgain) Phi='deg' Theta='deg' d B ( P e a k G a in ) Figure 7: Simulated peak gain of the proposed SWB antenna (c) Radiation Pattern Freq='15.445GHz' Phi='deg' Freq='15.445GHz' Phi='9deg' Figure 6 shows the both 2D and 3D E-plane and H-plane radiation patterns of the proposed SWB antenna measured at 3, 5.2, 9.9 and GHz respectively. From these figures, it is clear that the nearly omnidirectional radiation patterns is achieved in the H-plane (Y-Z plane) and bidirectional radiation patterns in E-plane (X-Y plane) and even at the higher frequencies. Figure 7 gives the simulated peak gain variation of the proposed monopole antenna. As seen from Figure 7 the raising peak gain from 1-13 db at 5.4 GHz and maintained constant around 7 8 db over the entire SWB band CONCLUSIONS A new compact arch-shaped SWB monopole antenna with loading wide rectangular slots into its bottom ground plane is successfully implemented. By loading the optimized dimensions of wide rectangular slots into bottom ground plane the super-wideband (SWB) is produced and covers the frequency band of GHz. This antenna gives a -1dB

5 impedance bandwidth of 189% with 34.5:1 ratio impedance bandwidth. From the obtained results, the antenna has a good omnidirectional radiation patterns even at higher frequencies and enhanced peak gain of 13 db is observed at 5.4 GHz and at the entire UWB band the 7-8 db gain is also observed. The proposed antenna has a compact in size, simple in its configurations and low cost which is most useful for SWB communications systems. ACKNOWLEDGEMENT This research work is supported financially by the Jawaharlal Nehru Memorial Fund (JNMF), New Delhi, India for providing JN Scholarship for Doctoral Studies to the corresponding author. REFERENCES Ansoft HFSS, 3D EM-field simulation for high performance electronic design. ver. 11, Ansoft Corp., Pittsburgh, PA, 28 antenna for UWB systems,ieee Transactions on Antennas Propagation 53(11): Jung, Jihak, Wooyoung Choi, and Jaehoon Choi. 25. A Small Wideband Microstrip-Fed Monopole Antenna. IEEE Microwave and Wireless Components Letters 15(1): K. R. Chen, C.Y. D.Sim and J. S. Row A compact monopole antenna for super wideband applications, IEEE Antennas Wireless PropagagationLetters 1: X. R. Yan, S. S. Zhong, and X. L. Liang. 27. Compact printed semi-elliptical monopole antenna for super-wideband applications, Microwave Optical Technological Letters 49(9): Z. N. Chen, T. S. P. See, and X. Qing. 27. Small printed ultrawideband antenna with reduced ground plane effect, IEEE Transactions on Antennas Propagation 55(2): Azenui, N.C., and H.Y.D. Yang. 27. A Printed Crescent Patch Antenna for Ultrawideband Applications. Antennas and Wireless Propagation Letters 6(11): C. Deng, Y. J. Xie, and P. Li. 29.CPW-fed planar printed monopole antenna with impedance bandwidth enhanced, IEEE Antennas Wireless Propagation letters, 8: C. Y. Huang and W. C. Hsia.25. Planar elliptical antenna for ultra-wideband communications, Electronics Letters 41(6): Choi, S. H., J. K. Park, S. K. Kim, and J. Y. Park.24. A new ultra wideband antenna for UWB applications, Microwave and Optical Technology Letters 4(5): Commission, Federal Communication. 22. Revision of Part 15 of the Commission s Rules Regarding Ultra-Wideband Transmission Systems. First Report and Order in ET (FCC2-48): J. Liang, C. C. Chiau, X. Chen, and C. G. Parini. 24. Printed circular disc monopole antenna for ultra-wideband applications, Electronic Letters 4(2): J. Liang, C. C. Chiau, X. Chen, and C. G. Parini. 25 Study of a printed circular disc monopole