 Kurdistan Journal of Applied Research (KJAR) | Print-ISSN: 2411-7684 – Electronic-ISSN: 2411-7706 | kjar.spu.edu.iq Volume 2 | Issue 3 | August 2017 | DOI: 10.24017/science.2017.3.27 Design and Simulation of Microstrip Patch Antenna for Wireless Applications Kawan F. Ahmed Communication Eng. Dept. Technical College of Engineering Sulaimani Polytechnic University Sulaimani, Iraq kawan.ahmed@spu.edu.iq Rawaz H. Abdullah Communication Eng. Dept. Technical College of Engineering Sulaimani Polytechnic University Sulaimani, Iraq rawaz.abdullah@spu.edu.iq Dana S. Abdalla Communication Eng. Dept. Technical College of Engineering Sulaimani Polytechnic University Sulaimani, Iraq Abstract: In this paper two rectangular microstrip patch antennas are designed to operate in and bands, using Computer Simulation Technology (CST) Microwave Studio. The designed antenna can be used for industrial, scientific and medical (ISM) band applications. The RO4350B hydrocarbon ceramic laminates from ROGRES corporation substrate is chosen in the design of the dielectric substrate of the antennas. The designed antenna has low profile, low cost, easy fabrication and good isolation. The parameters such as return loss, voltage standing wave ratio (VSWR), antenna gain, radiation pattern has been simulated and analyzed. Keywords: Microstrip patch antenna, dielectric substrate, Computer Simulation Technology (CST), Industrial Scientific and Medical (ISM) bands, voltage standing wave ratio (VSWR), antenna gain. 1. INTRODUCTION An antenna plays a very important role in wireless communication systems. Microstrip patch antennas are attractive for low-profile wireless applications at frequencies above because of their low weight, cheap, and portability. As shown in Figure-1, a microstrip antenna in its simplest configuration consists of three layers; a radiating patch on the top, a dielectric substrate that underlies the patch, and a ground plane at the bottom [1] [2]. Figure-1: Microstrip patch antenna The metallic patch normally made of conductors such as copper or gold. Although it can take different configurations, rectangular and circular patches are the most popular in practice, due to their attractive radiation characteristics. The dimensions of the patch are smaller compared to the substrate and ground [3] [4]. 2. LITERATURE REVIEW In this section a review of relevant works is studied. The approaching maturity of microstrip antenna technology coupled with the increasing demand and applications for such devices has resulted in a huge volume of research work in the field of microstrip antennas. An array of Rectangular Microstrip Antenna (RMSA) with comparison to a single patch RMSA is designed in [5] using IE3D simulator for wireless local area network (WLAN) applications, at . In this work the FR4 substrate is chosen in the design process. The substrate has a dielectric constant of with a thikness of . Maximum gain of is achieved by using four by two (4x2) array of eight patches as compared to for single patch. The dimensions of the designed path were , and . In [6] the substrate FR4, which has a dielectric constant of with a thikness of , is proposed to be used to design a microstrip patch antenna, with the dimensions of , and . The antenna is designed and simulated in Ansoft-HFSSV13 for WLAN and ISM applications. The designed antenna provides of bandwidth at with a gain of . A review on the design and development of microstrip patch antennas at were studied in [7]. Mostly the FR4 substrate were used in the previous works with a thickness of as in [5], [6], and [7]. In this paper the RO4350B hydrocarbon ceramic laminates from ROGRES corporation substrate is chosen in the design of two different single-microstrip patch antennas to operate in the and unlicensed instrument, scientific, and medical (ISM) bands. The proposed RO4350B substrate has the dielectric constant with a thickness of . Therefore, the thickness or height of the chosen dielectric substrate is much thinner, and is about two-times less than compared to the related works, which has the advantage of the reduction in the weight, size, and dielectric loss of the antenna. Beside this interesting point, the proposed antenna performance in mailto:kawan.ahmed@spu.edu.iq mailto:rawaz.abdullah@spu.edu.iq terms of bandwidth, gain and VSWR is almost the same or better than the previous works 3. DESIGN CONSIDERATIONS The resonant frequency is a key parameter for the design of microstrip patch antennas and must be selected properly to fit the application requirements. Dimensions (width and length) of a microstrip patch antenna depend on the resonant frequency and value of the dielectric constant of the substrate. The width and length of a rectangular patch are calculated as follows [4] [5]: √ (1) √ (2) √ (3) Where, : is the seed of light : is the effective dielectric constant : is the height of the substrate The dimension of a substrate is equal to that of the ground plane. Typically, the dimension of the ground plane is assumed to be infinite during the analysis and design of microstrip patch antennas. In an actual application only a finite size ground plane can be implemented, which makes diffraction of radiation from the edges of the ground plane, and resulting in a change in radiation pattern, radiation conductance, and resonant frequency of the antenna. Therefore, the size of the ground plane is to be greater than the patch dimensions by approximately six times the substrate thickness. The length of a ground plane ( ) and the width of a ground plane ( ) are calculated using the following equations [4]: (4) (5) There are different methods for feeding the microstrip patch antennas, such as feed line method, coaxial probe feeding method, etc. In this work the feed line method is used. 4. RESULTS In this work two single-microstrip patch antennas are designed to operate at and respectively. The initial or approximate dimensions of each antenna are determined based on the design equations given from (1) through (5). The RO4350B dielectric is used to design the substrate which has the dielectric constant with a thickness of . The design parameters of the antennas are shown in Figure-2. Lg Wg W L g d Wf Lf Figure-2: Design parameters of the proposed antenna The designed antennas were simulated using the CST microwave studio. The dimensions of the proposed antennas are changed and optimized during the simulation process to get better performance of the antenna, i.e. radiation patterns, standing wave ration, bandwidth, and antenna gain. Table-1 depicts the material specifications and design parameters of the designed antenna at . Table-1: Design parameters of the designed antenna at . Center frequency, Substrate RO4350B Substrate height, dielectric constant, Length of the patch, Width of the patch, Length of the substrate, Width of the substrate, Length of microstrip feed, Width of microstrip feed, Distance of inset feed, Gap between microstrip feed and patch, Thickness of the patch, t Figures-3 shows the simulated far-field directivity or the radiation pattern for the designed antenna at . The results show that the designed microstrip patch antenna mainly radiates in the vertical direction. This is in agreement with the theoretical radiation pattern for these structures. The antenna has a gain of . Figure-3: Far-field directivity of the antenna The simulated S-parameter versus frequency for the designed antenna at is presented in Figure-4. It can be seen that the simulated center frequency is slightly shifted from the . The antenna has a return loss of at . The bandwidth of the antenna is about , as shown in Figure-5. Figure-4: Return loss (S11) of the designed antenna Figure-5: Bandwidth of the designed antenna The voltage standing wave ratio (VSWR) of the antenna at the resonant frequency is about , as shown in Figure-6. Figure-6: VSWR for the designed antenna at Table-2 illustrates the material specifications and design parameters of the designed antenna at . Table-2: Design parameters of the designed antenna at . Center frequency, Substrate RO4350B Substrate height, dielectric constant, Length of the patch, Width of the patch, Length of the substrate, Width of the substrate, Length of microstrip feed, Width of microstrip feed, Distance of inset feed, Gap between microstrip feed and patch, Thickness of the patch, t Figures-7 shows the Far-field directivity radiation pattern for the designed antenna at . Similarly, as the previous design, the antenna mainly radiates in the vertical direction. The antenna has a gain of . Figure-7: Far-field directivity of the antenna The simulated S-parameter versus frequency for the designed antenna at is presented in Figure-8. It can be seen that the simulated center frequency is shifted from the designed target, but still very close to . The antenna has a return loss of at . The bandwidth of the antenna is about , as shown in Figure-9. Figure-8: Return loss (S11) of the designed antenna Figure-9: Bandwidth of the antenna The VSWR of the patch antenna is about at , which is practically strongly acceptable, as shown in Figure-10. Figure-10: VSWR for the designed antenna 5. DISCUSSION In this paper two different patch antennas were designed using a dialectic substrate with a thickness of which is much narrower than the related works as done in [5], [6], and [7]. The designed antenna has comparable dimensions as given in the related works. The antenna has a maximum gain of with a main lobe in the direction of theta = 0 degrees and phi = 0 degrees was obtained. The simulated gain is a much higher compared to the results reported in [6] but comparable to that given in [5]. The return loss of the antenna is slightly less than the related works, and it has better and more desired value of VSWR. The dimensions of the designed are much less than in that of the antenna. The bandwidth of the designed antenna is , while the bandwidth of the designed antenna is . These obtained values of bandwidth are less than compared the results reported in [5], [6], and [7]. Therefore, it can be depicted that the proposed designs can be much useful in the design of wireless systems that require narrow bandwidth such as sensor networks that lie in the ISM bands. 6. CONCLUSION In this study the RO4350B substrate is proposed in the design of two different single microstrip patch antennas to operate at 2.4 and 5.2 ISM bands. The thickness or height of the chosen dielectric substrate is much thinner which has the advantage of the reduction in the weight of the proposed antenna with a good performance in gain, return loss, and VSWR is the important futures of the proposed antennas for various wireless applications including wireless sensor networks, wireless telemedicine devices, and WLANs. 7. REFERENCES [1] J. D. Kraus and R. J. Marhefka, Antennas for all applications, 3rd ed., NewYork: McGraw-Hill, 2002. [2] C. A. Balanis, Antenna Theory: Analysis and Design, 3rd ed., New Jersey: John Wiley & Sons, 2005. [3] P. Bhartia, I. Bahl, R. Garg and A. Ittipiboon, Microstrip Antenna Design Handbook, Norwood, MA: Artech House Inc., 2001. [4] Y. Y. Woldeamanuel, "Design of a 2.4 GHz Horizontally Polarized Microstrip Patch Antenna using Rectangular and Circular Directors and Reflectors," The University of Texas at Tyler, USA, November, 2012. [5] Amitha.R.Nair, B. A. Singh and S. S. Thakur, "Design of Rectangular Microstrip 4x2 Patch Array Antenna at 2.4 GHz for WLAN Application," in IEEE Second International Conference on Advances in Computing and Communication Engineering, 2015. [6] V. Asokan, S. Thilagam and K. K. Vinoth, "Design and Analysis of Microstrip Patch Antenna for 2.4GHz ISM Band and WLAN Application," in IEEE Sponsored 2nd International Conference on Electronics And Communication System (ICECS), 2015. [7] C. R.Salian, B. Santhosh and S. Vedagarbham, "Review on Design and Development of Low Cost 5GHz Microstrip Patch Array Antenna," in International Conference on Innovative Mechanisms for Industry Applications (ICIMIA), 2017.