Design, Realization And Measurements of Microstrip Patch Antenna Using Three Direct Feeding Modes For 2.45ghz Applications

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1 International Journal of Computer Engineering and Information Tecnology VOL. 9, NO. 8, August 2017, Available online at: E-ISSN (Online) Design, Realization And Measurements of Microstrip Patc Antenna Using Tree Direct Feeding Modes For 2.45gz Applications Ouadiaa BARROU 1, Abdelkebir EL AMRI 2 and Abdelati REHA 3 1, 2 RITM Laboratory, CED Engineering Sciences, ESTC, Hassan II University, Casablanca, Morocco 3 Electronic Department, Telecommunication Laboratory, ISGA, Marrakec, Morocco 1 ouadiaa.barrou@gmail.com, 2 elamri_abdelkebir@yaoo.fr, 3 abdelati.rea@isga.ma ABSTRACT A microstrip patc antenna is a metal patc placed on a substrate. Different feeding modes are used suc as: coaxial probe feed, microstrip line feed, proximity-coupled feed, coplanar wave guide feed (CPW) and oters. Tese feeding modes are divided in two kinds, direct or indirect. Te patc can take different sapes; te most known forms are rectangular, square, circular, exagonal... Te microstrip patc antenna is low-profile, conformable to planar and non-planar surfaces, simple and ceap to manufacture using modern printed-circuit tecnology. In tis paper, a microstrip patc antenna for 2.45GHz applications is designed based on te transmission line metod. Te design is optimized wit te Metod of te Moments (frequency domain metod) because it s one of te accurate metods for wire and planar antennas. Te tree direct feeding modes are studied, manufactured and measured. Simulations were performed wit CADFEKO and measurements were performed wit Vector Network Analyzer (VNA) Anritsu MS2026C. Keywords: Antenna Design, Feeding Modes, Microstrip Patc Antenna. 1. INTRODUCTION Wit te development of wireless applications and teir integration in restrict environment like smartpones, laptops and oter embedded systems, te microstrip patc antennas are widely used because of teir planer structure, low profile, ligt weigt good efficiency, ease of manufacturing and integration wit active devices. Tere are many configurations tat can be used to feed microstrip antennas. Te most popular are te coaxial probe, microstrip line, proximity coupling, coplanar wave guide and oters. Eac feeding mode ave some advantages and disadvantages and it was be used in depending on te requirements[1] [7]. In tis paper, first, a design metodology is presented. Next, te tree direct feeding modes are simulated, manufactured and measured. After tat, a comparison of te results is presented. 2. THE PATCH ANTENNA DESIGN METHODOLOGY 2.1 Te Design of Miscrostrip Patc Antenna Te microstrip patc antennas can be analyzed in various metods, te most popular are: Transmission-line metod (TLM) Cavity metod (CM) Full-wave metods: Are based on solving Maxwell s equations in differential or integral forms. Te most popular are te Metod of te Moments (MoM), te Finite element metod (FEM), Finite-Difference Time Domain (FDTD)[2], [8] [10]. Altoug te transmission line model as te least accuracy, it is te easiest metod to implement and gives good pysical insigt. According to Balanis[1], te transmission-line model represents te microstrip antenna by two slots wit a widt of W and separated by a transmission line of lengt L (Fig. 1). For te microstrip line sown in Fig. 2 (a), te field lines are inside te substrate and some of tem are extended to outer space (Fig. 2 (b)). For tis, an effective dielectric constant ( reff ) is introduced to account for fringing and te wave propagation in te line (Fig. 2 (c)).

2 151 reff can be calculated from [1] by te formula (1) 1-2 r 1 1 r reff W (1) Were, W/ >1 reff : Effective dielectric constant r : Dielectric constant of te substrate W: Widt of te radiating patc : Heigt of te substrate Fig.2. Microstrip line and its electric field lines, and effective dielectric constant geometry [1] Fig.1. Microstrip antenna [1] As sown in Fig. 3, fringing effects looks greater tan te microstrip patc dimensions. For te principal E-plane (xy-plane), te dimensions of te patc along its lengt ave been extended on eac end by a distance L, wic is a function of reff and W/ given from [1] by te formula (2). W ( 0.3) ( 0.264) L reff (2) W ( reff ) ( 0.8) Te effective lengt of te patc is given by te equation (3). L 2. L (3) L eff It is also given by te equation (4). L eff (4) 2 reff Fig.3. Pysical and effective lengts of rectangular microstrip patc [1] Te widt of te patc is given from [1] by te equation (5) 2 W 2 1 r Were, is te wavelengt given by te equation (6) c (6) f To design a microstrip patc antenna operating in te frequency of 2.45GHz wit te parameters: = 1.6mm and r = 4.4 we follow te previous steps. Te results are: W = 37.26mm, L = 28.83mm (5)

3 Feeding Modes Tere are many configurations tat can be used to feed microstrip antennas. Tese feeding modes are divided in two kinds, direct or indirect. Te tree direct modes are: microstrip line, coaxial probe, coplanar wave guide. (Fig. 4) feeding probe is placed at te point F, placed at te y f position from te center of te patc (y f = 4mm). Fig. 5. Geometry of te patc antenna wit coaxial probe fed Fig. 6 sows te S 11 parameters. Te simulated resonance frequency is 2.33GHz, 130MHz lower tan te resonance frequency given by TLM. Te design is optimized to ave 2.45GHz as te resonance frequency wit MoM. Te new dimensions of te patc are: W p = 35.66mm and L p = 27.56mm. fig. 7 sows te S 11 for te optimized antennas. To ave a good impedance matcing, te feeding point must be placed at a specific position. For tat a parametric study is done. Fig. 8 sows te beavior of S 11 versus y f. We observe tat we ave a good impedance matcing for y f = 6mm. Te 3D gain pattern is sown in Fig. 9, te maximum gain is 4.6dB. Fig. 4. Te tree direct feeding tecniques [1], [5] In te next section, simulation, realization and measurement of te rectangular patc antenna will be done wen we feed it wit te tree direct feeding tecniques. 3. SIMULATION, REALIZATION AND EASUREMENTS FOR DIFFERENT FEEDING MODES To validate te previous design, te microstrip patc antenna was simulated wit CADFEKO witc based on te Metod of te Moments (MoM), one of te more accurate metods for wire and planar antennas[8] [12]. Tree direct feeding modes are studied: coaxial probe, microstrip line, and CPW. Fig. 6. S 11 parameter for te patc antenna wit coaxial probe fed 3.1 Coaxial probe Feeding Fig. 5 illustrates te geometry of te patc antenna fed by a coaxial prob. Te antenna is printed on a substrate EPOXY FR4 wit relative permittivity ε r = 4.4 and a tickness of 1.6mm. Te oter parameters are: W p = 37.26mm, L p = 28.83mm, W s = 2W p, L s = 2L p. Te Fig. 7. S 11 parameter for te optimized patc antenna wit coaxial probe fed

4 153 Fig. 8. Parametric study of S 11 versus y f Fig. 11. Simulated and measured S 11 parameter for te rectangular patc antenna wit probe feeding 3.2 Microstrip Line Feed Te same patc antenna is fed by a microstrip line smaller in widt as compared to te patc and aving a caracteristic impedance of 50Ω. Te widt of tis line is 2.95mm based on te equation (7). Fig. 9. 3D gain pattern for te resonance frequency (fr = 2.45GHz) After realization and measurements (fig.10) of te rectangular patc antenna wit probe feeding and wit y f =6mm, a good agreement is observed between simulation and measurement in term of S 11 parameter (fig.11). 120 Z0 Wf Wf r ln 1.44 (7) Wit Z 0 : te caracteristic impedance of te microstrip line. W f : te widt of te microstrip line. : te ig of te substrate. (a) Rear side (b) Front side Two configurations are studied, te first one witout te inset feed point (fig. 12(a)), te second one wit te inset feed point (fig. 12 (b)). Te S 11 parameter and te 3D gain pattern for te two configurations are given by Fig.13. We observe tat wen we set up te inset feed point; we obtain a good impedance matcing and a better efficiency. Also a parametric study is done to know te effect of te lengt of te inset point (y 0 ). Fig. 14 sows te variation of S 11 versus y 0. A better impedance matcing is obtained wen y 0 = 7.5mm. (c) Measurement wit VNA Anritsu MS2026C Fig. 10. Fabricated patc antenna wit probe feeding (a-b) and measurement wit ANRITSU VNA (c) (a ) (b) Fig. 12. Geometry of te patc antenna wit Microstrip Line Feed

5 154 Fig D gain pattern and S 11 parameter for te two configurations Fig. 16. Simulated and measured S 11 parameter for te rectangular patc antenna wit probe feeding 3.3 CPW-feeding mode Tis kind of feeding tecnique is also called CoPlanar Wave guide feeding (CPW-feeding). Te ground plane is placed on te same plane as te patc as sown in fig. 17. Tis antenna is easy to manufacture compared to te tree first antennas using te Printed Circuit Board tecnique (PCB), in general it's used to obtain a large bandwidt, several studies used tis tecnique to design antennas for Ultra Wide Band (UWB) and Broadband antennas. Fig. 14. Parametric study of S 11 versus y 0 After realization and measurements (fig.15) of te rectangular patc antenna wit microstrip line feeding and wit y 0 =7.5mm, a good agreement is observed between simulation and measurement in term of S 11 parameter (fig.16). Fig. 17. Geometry of te patc antenna wit CPW-feeding Te S 11 parameter of te antenna is given by fig. 18. We observe tat te resonance frequency is 2.6GHz wit a large -10dB bandwidt (420MHz: GHz). Te 3D gain pattern is given by fig. 18, we observe tat te maximum gain is 1.3dB, also te antenna is omnidirectional. Fig. 15. Fabricated patc antenna wit microstrip line feeding and measurement wit ANRITSU VNA

6 155 Fig. 18. S 11 parameter for te patc antenna wit CPW-feeding mode 4. COMPARISON OF DIFFERENT FEEDING MODES Fig D gain pattern for te patc antenna wit CPW Feed After realization and measurements (fig.20) of te rectangular patc antenna wit CPW feeding, a good agreement is observed between simulation and measurement in term of S 11 parameter (fig.21). Fig. 20. Fabricated patc antenna wit CPW feeding and measurement wit ANRITSU VNA Eac studied configuration as some advantages and disadvantages. Te patc antenna wit CPW feeding tecnique is simple to manufacture, omnidirectional, broadband but aving a poor gain. Te antenna wit coaxial probe feed and microstrip line feed ave te same beavior. Tere gain is important, directional but aving a low bandwidt. Table 1 summarizes simulated and measured resonance frequencies, S11 parameter and bandwidts. Table 1: simulated and measured resonance frequencies, S 11 parameter and bandwidts for te tree feeding modes Resonance frequency (GHz) S 11 (db) Bandwidt (From-To) Probe feeding Simulated MHz ( ) Measured MHz ( ) Microstrip Line feeding Simulated MHz ( ) Measured MHz ( ) CPW feeding Simulated MHz ( ) Measured MHz (2.3-3)

7 CONCLUSIONS Te microstrip patc is an adequate solution to design low profile antennas wit important performances. It s also a good solution for designing embedded systems were te weigt, cost and te ease of installation are te important requirements. Te different feeding modes allow aving some advantages: Te CPW feeding mode increases te bandwidt of te antenna and aving omnidirectional gain pattern. Te coaxial probe and microstrip line feeding modes allow aving antennas wit sort bandwidt and important gains. To design microstrip patc antenna, te adopted feeding mode will be depend on te requirements performances. As perspective of tis work, te indirect feeding modes like proximity coupled and aperture feeding sould be studied. Opt. Tecnol. Lett., vol. 51, no. 5, pp , May REFERENCES [1] C. A. Balanis, Antenna teory: analysis and design, Fourt edition. Hoboken, NJ: Wiley, [2] Y. Huang and K. Boyle, Antennas: from teory to practice. Cicester, UK: Jon Wiley & Sons Ltd, [3] W. L. Stutzman and G. A. Tiele, Antenna teory and design, 3rd ed. Hoboken, NJ: Wiley, [4] [4] J. L. Volakis, Ed., Antenna engineering andbook, 4t ed. New York: McGraw-Hill, [5] O. Barrou, A. El Amri, and A. Rea, Comparison of Feeding Modes for a Rectangular Microstrip Patc Antenna for 2.45 GHz Applications, in Advances in Ubiquitous Networking 2, vol. 397, R. El-Azouzi, D. S. Menasce, E. Sabir, F. De Pellegrini, and M. Benjillali, Eds. Singapore: Springer Singapore, 2017, pp [6] P. S. Bakariya, S. Dwari, M. Sarkar, and M. K. Mandal, Proximity-Coupled Microstrip Antenna for Bluetoot, WiMAX, and WLAN Applications, IEEE Antennas Wirel. Propag. Lett., vol. 14, pp , [7] J. Abraam, T. Matew, and C. K. Aanandan, A NOVEL PROXIMITY FED GAP COUPLED MICROSTRIP PATCH ARRAY FOR WIRELESS APPLICATIONS, Prog. Electromagn. Res. C, vol. 61, pp , [8] S. Clarke and U. Jakobus, Dielectric material modeling in te MoM-based code FEKO, IEEE Antennas Propag. Mag., vol. 47, no. 5, pp , Oct [9] A. Rea and A. O. Said, Tri-Band Fractal Antennas for RFID Applications, Wirel. Eng. Tecnol., vol. 04, no. 04, pp , [10] R. Sun, Te Computer Simulation of Radiation Pattern for Cylindrical Conformal Microstrip Antenna, Mod. Appl. Sci., vol. 3, no. 10, Sep [11] D. B. Davidson et al., Recent progress on te antenna simulation program FEKO, 1998, pp [12] X. W. Zao and C. H. Liang, Performance comparison between two commercial EM softwares using iger order and piecewise RWG basis functions, Microw.