International Journal of Modern Trends in Engineering and Research www.ijmter.com e-issn No.:2349-9745, Date: 28-30 April, 2016 Printed Circular Patch Antenna Priyanka T. Chaudhari Department of E&TC Engineering, SVIT Chincholi, Nashik, priyatc19@gmail.com Abstract- Designing the UWB antenna can be one of the most challenging of these issues. UWB antennas must cover an extremely wide band, 3.1 GHz to 10.6 GHz for the indoor and handheld UWB applications, have electrically small size, and hold a reasonable impedance match over the band for high efficiency. One of the printed antennas which has large attention recently is Printed monopole antenna. They offer large band width and are more attractive for wireless communication applications. The large ground plane used for the conventional Printed monopole is the main limitation. However, the move towards the truncated ground plane has made the antenna low profile and suitable for integration into circuit board as terminal antennas. This paper focuses on Printed Circular Monopole antenna design and analysis. Studies have been undertaken covering the microstrip antenna theory. All the types of antenna were simulated and analyzed by using IE3D software. The performance of those antenna are further compared on the basis of parameters like return loss, VSWR, gain etc. From experimental demonstration it is clear that, one can improve the bandwidth of Printed Monopole antenna by inserting the transitions in micro-strip feed line and design can be used as UWB antenna. Keywords:Micro-strip Antenna, Printed Monopole Antenna, UWB, Transition feed line, IE3D. I. INTRODUCTION A band of 3.1GHz to 10.6 GHz is covered by the Ultra Wide Bane which is allotted by Federal Communication Commission (FCC). Demand of UWB antennas is increasing since there is rapid growth in the Ultra Wide Band communication. Ultra wide band systems have some fundamental differences from conventional narrow band systems as it has larger bandwidth which offers specific advantages with respect to signal robustness, information content and/or implementation simplicity. [1] An antenna is a very essential element in UWB system because it acts as a band pass filters to reshape the pulse spectra. So antennas should be carefully designed to avoid unnecessary distortions. Designing of an antenna is one of the most important challenges for the designers. Printed antenna has features like low profile, small size, low weight and hence exploited for the compact applications such as mobile phones, other personal communication devices which becoming smaller and low weight day by day. Printed Monopole antenna offers large bandwidth & hence they have large attention among the all type of Printed Antennas recently. Microstrip antenna consists of radiating patch printed on grounded low loss substrate. The printed antenna can be of various shapes but rectangular and circular shapes are mostly used. There is great demand for UWB antennas that offer miniaturized planar structure, so the vertical disc monopole is still not suitable for integration with a PCB. This drawback limits its practical application. For this reason, a printed structure of the UWB disc monopole is well desired, which consist on printed radiator disc on substrate. Printed CDM antennas can be fed simple microstrip line, coplanar waveguide (CPW), or slotted structures. [8] In this paper design of circular monopole antenna is implemented for UWB applications, which consists of ground plane @IJMTER-2014, All rights Reserved
which is etched one & simple rectangular microstrip feed line is used. All the simulations & results are obtained by using IE3D software. II. GEOMETRY OF PRINTED CIRCULAR PATCH ANTENNA A circular disc monopole antenna is a planner structure. It consists of a circular patch having radius r and rectangular microstrip feed line both are printed on dielectric substrate. In Fig.1, L & W denotes the length and width of substrate. W f is width of the microstrip feed line. L f is length of microstrip feed line. Lg & Wg are the length and width of the partial conducting ground plane respectively. g is the gap between circular disk and ground plane. Ԑr is the dielectric constant for the substrate. h the height or thickness of the substrate. Figure 1. Geometry of circular monopole antenna III. DESIGNS OF CIRCULAR MONOPOLE ANTENNA FOR UWB APPLICATIONS By introducing simple microstrip transitions between the 50Ω feed line and the printed circular discs, the impedance BW of the planar monopole can be extended beyond 30GHz. Design C is basic circular monopole antenna having 50Ω microstrip feed line. Design A & Design B are formed by just introducing dual & single microstrip line transitions respectively [1]. Figure 2. Different 3 designs of circular monopole antennas [1] IV. SIMULATION AND RESULTS @IJMTER-2016, All rights Reserved 696
Figure 3. Implemented Designs A, B, C Simulation is done by using IE3D software. The different three designs are simulated. These designs are design A, design B and Design C as shown in Fig.3 The design C is a simple Printed Circular Monopole antenna with a simple microstrip feed line. Design B is obtained by modifying the microstrip feed line with a single transition, while Design A consists of two transitions in microstrip feed line of Design C. 4.1. VSWR Characteristics VSWR stands for voltage standing wave ratio. VSWR is always real & positive number for an antenna. It s ideal value is 1. Practical value of VSWR is 2. From the VSWR characteristics shown in Fig.4, Fig.5, Fig.6. It is clear that Designs have VSWR greater than 1 & less than 2. Figure 4. VSWR of designs A Figure 5. VSWR of designs B 4.2. S-Parameter It is considered that antenna having S (1,1) below 10dB can be used for the different applications. If S(1,1) is above 10dB, then there is no use of such antenna. The comparison s-parameter graphs for Design C, Design B & Design C are shown in Fig.7 The simulation of Design A, Design B, Design C gives the graphs for reflection coefficients with S (1,1) below 10dB. @IJMTER-2016, All rights Reserved 697
Figure 6. VSWR of designs C Figure 7. Comparison of S-Parameters 4.3. Radiation Pattern Figure 8. E plane radiation pattern comparison Figure 9. H plane radiation pattern comparison For linearly polarized antenna performance is described in terms of principal E-plane & H- plane patterns. E-plane is the plane containing the electric field vector & the direction of maximum radiation. While, H-plane is the plane containing the magnetic field. The radiation patterns of these three designs in E-plane & H-plane are shown in Fig.8, Fig.9 respectively. Radiation pattern are taken at frequency of 8.63GHz gives bidirectional pattern in E-plane & omni directional in H-plane. V. CONCLUSION Design A have better results than that of Design B & Design C. All the design provides most part of UWB. When all the graphs are taken under consideration, though S parameter of Design B gives maximum value of reflection coefficients, Design A gives more part of UWB as compared to other two designs. From experimental demonstration it is clear that, one can improve the bandwidth of Printed Monopole antenna by inserting the transitions in microstrip feed line and design can be used as UWB antenna. @IJMTER-2016, All rights Reserved 698
Table 1. Comparison of results of design A, B, C REFERENCES [1] Sarra Mohamed Nabil Srifi, Symon K. Podilchak,Mohamed Essaaidi, Compact Disc Monopole Antennas for Current and Future Ultra wideband (UWB) Applications IEEE Transaction On Antennas and Propagation, VOL. 59, NO. 12, DECEMBER, 2011 [2] Raha Eshtiaghi, Javad Nourinia, And Changiz Ghobadi, Electro magnetically Coupled Band Notched Elliptical Monopole Antenna For UWB Applications, IEEE Transactions On Antennas And Propagation, Vol. 58, No. 4, April 2010. [3] Bharat Bhushan Agrawal, PriyadarshiSuraj, Vibha Rani Gupta, Printed Monopole Antenna for UWB Application, International Journal of Microwave AND Optical Technology,Vol.5 No.4 July 2010 [4] M. Sun, Y. P. Zhang, and Y. Lu, miniaturization of planar monopole antenna for ultrawide band radios IEEE Trans. Antennas Propag., vol.58, no. 7, pp. 2420, Jul. 2010. [5] R. Zaker and A. Abdipour, Avery compact ultrawide band printed omni directional monopole antenna IEEE Antennas Wireless Propag. Lett., vol. 9, pp. 471473, 2010. [6] J. Liang, L. Guo, C. C. Chiau, X. Chen, and C. G. Parini, Study of CPW fed circular disc monopole antenna for ultra wideband applications IEEE Proc. Microw. Antennas Propag., pp.520,dec.2005. [7] Taeyoung Yang, Seong-Youp Suh, Randall Nealy, William A. Davis, and Warren L. Stutzman, Compact Antennas For UWB Applications, wcsp:eng:usf:edu=uwb Testbed Docs [8] Mohamed Nabil Srifi, Ultra-Wideband Printed Antennas Design, Ultra Wideband Communications: Novel Trends Antennas and Propagation,www.intechopen.com [9] K. Francis Jacob, Printed Monopole Antenna For Ultra Wide Band (UWB)Applications Thesis, Cochin University, June 2008. [10] Jianxin Liang, Antenna Study and Design for Ultra Wideband Communication Applications, Thesis, University of London, United Kingdom,July 2006 [11] Girish Kumar, K. P. Ray, Broadband Microstrip Antenna, Artech House Boston, London, 2003 [12] Debatosh Guha, Yahir Antar, Microstrip and Printed Antennas, John Wiley and Sons Ltd., First Edition,2011. [13] Rodney B. Waterhouse, Microstrip Patch Antenna, John Wiley and Sons Ltd., First Edition,2011 [14] R. Garg, P. Bhartia, I. Bahl, and A. Ittipiboon, Microstrip Antenna Design Handbook,Norwood, MA: Artech House, Inc., 2001. @IJMTER-2016, All rights Reserved 699