2.45GHz Yagi Antenna

Transcription

1 2.45GHz Yagi Antenna Pramod D. Waikar 1, Omkar S. Teli 2, Saurabh A. Shinde 3, Pankaj P. Mali 4, Brijesh R. Yadav 5 1 Assistant Professor, 2 UG Student, 3 UG Student, 4 UG Student, 5 UG Student, Department of Electronics and Telecommunication Engineering, Rajendra Mane College of Engg. & Tech., Ambav (Devrukh) , India. Abstract Yagi Uda antenna is very directive, gives very high gain and cheap. Antenna which works frequency above 2000MHz called microwave antennas. Generally above 2000MHz use of other antennas rather than Yagi antenna. 2.45GHz is WiFi operating frequency. 2.45GHz Yagi antenna useful for WiFi application as receiver for laptop, it can extend laptop WiFi signal in one direction. In this paper design of yagi antenna of 1 Reflector, 1 Simple Dipole Driven element and 9 Directors presented. Design done by first therotical calculations and then using YagiCAD6 6.1 simulation software. YagiCAD gave Gain, Zin, VSWR and then fabricated antenna tested by Vector Network Anlyazer. I. INTRODUCTION Yai Uda antenna is generally use for frequency greater than 15MHz. It is widely used in applications where requirement of high gain and directivity. In this paper, we studied 2.45GHz yagi antenna, which can be used for WiFi. Various design parameters of the Yagi antenna are S11, Impedance, VSWR, are considered in this work. The geometry of the Yagi antenna is shown in Fig. 1, A basic Yagi consists of two or three straight elements, each measuring approximately ½ electrical wavelengths. It consists of single DRIVEN element and a number of parasitic element; made up of REFLECTOR and DIRECTORS.[1] The REFLECTOR is placed behind the DRIVEN element for maximum gain and directivity, while the DIRECTORS are placed in front of the DRIVEN element for maximum gain and directivity. The dimensions of the elements are: Yagi element spacing: ( , , , , , , , , , ). Yagi element lengths: (0.0578, , , , , , , , , , ). Yagi element radii: ( , , , , , , , , , , ). Figure 1 Fabricated Yagi Antenna A load impedance of 50 ohms and gain of dbi were obtained. II. THEROTICAL FORMULATION 11 Element Yagi Antenna Formation Reflector length = 500/f(MHz) feet Driver element length = 475/f(MHz) feet Director1 length = 455/f(MHz) feet Further 8 Directors lengths get reduces than previous director by 5% but here we use same director lengths. Spacing between driven and parasitic elements are usually used in practice are of the order of λ/10 i.e.0.1λ to 0.15λ[2]. III. SIMULATION RESULTS Therotical designed antenna simulate in YagiCAD6 6.1 then it optimize by option available Auto optimize in YagiCAD for Gain, VSWR. Proper optimization gave required Gain, Input impedance, VSWR, Radiation Pattern. Simulation Gave following reults; Gain = dbi F/B = db Zin = j13.75 VSWR =

2 A. Basic International Journal of Emerging Technology and Advanced Engineering Figure 2 Basic Parameters 527

3 B. Pattern International Journal of Emerging Technology and Advanced Engineering C. Effective Gain and VSWR Figure 3 Radiation Pattern Figure 4 Gain & VSWR for Frequencies 528

4 IV. FABRICATION AND TESTING Antenna element is of aluminium of 37mm diameter and straight wooden plank used to mount the element. Driven element is cut at center and solder the braid and copper wire of LMR200 (50Ω) coaxial cable to 2 parts of simple dipole. Complete fabricated antenna is tested by Vector Network Analyzer (VNA). VNA shows S11, Input impedance, VSWR. VNA results are as follows: A. S11 Figure 5 S11 Parameter for Frequencies 529

5 B. Smith Chart C. VSWR Figure 6 Input Impedance for Frequencies Figure 7 VSWR for Frequencies 530

6 V. COMPARISON TABLE Ⅰ YAGICAD6 6.1 SIMULATION & VNA TESTED RESULTS Antenna Parameter Simulated Tested Zin j j3.73 VSWR Bandwidth 147 MHz 151 MHz( MHz) VI. CONCLUSION 88MHz( MHz) 2.45GHz Yagi antenna is designed for 11.92dBi, VSWR 1.328, Zin=55.75-j13.75 but after fabrication and testing, got good results for GHz. This happens because of limitations of YagiCAD as there we had not consider atmospheric impedances, Cableconnector loss, impedance of VNA and faults in fabrication process. REFERENCES [1] O. Shoewu, L. A Akinyemi, N. T. Makanjuola, Design, Development and Simulation of a 2.4 GHz Yagi Uda Antenna, Volume 2 Issue 5 ǁ May ǁ PP [2] Antenna Wave Propagation by K.D. Prasad (Chapter 9, Practical antennas part II) 531