International Journal of Electronics Engineering Research. ISSN 0975-6450 Volume 9, Number 4 (2017) pp. 517-525 Research India Publications http://www.ripublication.com Reconfigurable Patch Antenna For Software Defined Radio Application Sharanagouda N Patil Research Scholar Dept. of P.G Studies and Research in Applied Electronics, Gulbarga University, Kalaburgi 585102, Karnataka, India. Prof. P.V.Hunagund Professor Dept. Of P.G Studies and Research in Applied Electronics Gulbarga University, Kalaburagi-585102, Karnataka, India. Prof. R.M.Vani Reader & Head Dept. of University Science and Instrumentation Centre (USIC) Gulbarga University, Kalaburgi 585102, Karnataka, India. Ravi M Hatti Assistant Professor Dept. OF E&CE, BLDEA College of Engineering Vijaypur, 586103, Karnataka, India. Abstract We present in this paper, an innovative miniaturized Reconfigurable micro strip patch antenna (RMPA) with frequency agility. This antenna can be controlled by varying the switching state of two PIN diodes from the ON state to OFF state to switch it over two different mobile communication technologies. This antenna can be used as a RF front end in Software Defined Radio (SDR) applications. This antenna has been designed on a low cost FR4
518 Sharanagouda N Patil, Prof. P.V.Hunagund, Prof. R.M.Vani & Ravi M Hatti substrate with the size of 45*38*1.6mm 3 The prototype of this antenna has been simulated and tested. The simulated results validate the simulation predictions in terms of frequency agility performances. Keywords: Software Defined Radio,Reconfigurable,PIN Diode,Frequency agility. I. INTRODUCTION The integration of many functions in a single mobile device has made the reconfigurable antennas a necessity in modern wireless terminals. Due to support for more than one standard and to utilize the spectrum holes efficiently frequency agile antennas are playing an important role in Software Defined radios [1]. Frequency Reconfigurable antennas play a vital role in modern telecommunication systems [2].The Software Defined radio consists of a reconfigurable RF front end and base band system configured using a software layer[3]. In this paper, we propose an innovative design of a Frequency Reconfigurable Circular Patch Antenna (FRCPA) with switchable slot using two RF- PIN diode switches. This FRCPA can resonate flexibly at two operating frequencies depending on the operating state of these two RF PIN switches. The desired antenna radiation performance is obtained by wide ranging parametric study using HFSS OPTIMETRICS and in built optimization tool to get the desired dimensional values for FRCPA. The proposed antenna can resonate at 3 rd Generation and 4 th Generation (3G/4G) frequencies to support a single transceiver at RF front end. The frequency agility has been studied widely in many papers and novel techniques have been proposed for implementation of the RF switch circuits. Many articles have considered the use of the RF-PIN diodes and RF-MEMS, and J- FET for implementing the switching function [4].The PIN diode can be modeled as a RF switch at very high frequencies by suitable DC bias current applied at its two terminals The ON state can be ideally modeled as a conducting patch and a OFF state can be modeled as a very high resistance using the boundary conditions of HFSS [5]. RF MEMS switches can also be considered similarly for modeling using a transmission line model with conducting and a non conducting patch for modeling ON and OFF states. The practical considerations like parasitic resistance and capacitance have been considered using the Ansoft High Frequency Structure Simulator (HFSS) RLC boundary conditions [6]. The design of FRCPA has been discussed in section II, followed by presentation of simulation results section III. Finally, Results and future work are discussed in section IV.
Reconfigurable Patch Antenna for Software Defined Radio Application 519 II. DESIGN OF FRCPA A. Geometry of FRCPA The geometry of the proposed FRCPA antenna is shown in figure 1 and 2 below. Figure 1. Geometry of the FRCPA- Top view Figure 2. Geometry of the FRCPA Bottom view
520 Sharanagouda N Patil, Prof. P.V.Hunagund, Prof. R.M.Vani & Ravi M Hatti Table I: Dimensions of the frequency reconfigurable circular patch antenna Radius,R 8.00 mm Width,Wf 3.10 mm Length, Lsub 45.00mm Width, Wsub 40.00 mm Feed Length, Lf 26.00 mm Table II: Dimensions of the switchable slot L1 L2 L5 L3 L4 1.0 mm 2.5 mm 0.6mm 13.00 mm 13.00 mm The FRCPA consists of a substrate material of FR-4(Fire Retardant -4) grade. The foot print of the antenna is 45*40*1.6mm 3. The length of the ground plane is are 10.6 mm 2 and the radius of slotted circular patch is 8mm micro strip antenna is fed by a micro strip line with an impedance of 50 Ω with the dimension of 3mm width and 26.00 mm feed length calculated using TX-Line calculator of NI AWR tool. The slot is etched on a circular patch with two switches at the edges of the radiating edge as shown in figure1.the switches alter the radiating circumference of the FRCPA by changing the bias current through the RF PIN diode.
Reconfigurable Patch Antenna for Software Defined Radio Application 521 B. Switching model The model of the RF-switch is done using two techniques. In the ideal model, switches are modeled using a perfect electrically conducting (PEC) boundary in the HFSS for ON state. The patches are removed to mimic the OFF state of the RF -PIN diode. The switches are implemented in different ways in the literature[7-9]the practical model of the switch is modeled using the data sheet of the BAR67-02V PIN diodes from Infineon[10]. Consists of a Inductor L1= 0.3nH in series with a ON state forward resistance Rs=1Ω.The OFF state electrical equivalent circuit consists of Inductor L1=0.3nH in series with a parallel combination of capacitor CT=0.23pF, and Rp=2.5KΩ. Figure 3. Electrical equivalent of HFSS model of the switch. a) ON mode b) OFF state III. RESULTS AND DISCUSSION The return loss for the switchable slot FRCPA antenna in mode-1,i.e. when both the switches are ON is given in the figure 4.The antenna resonates at frequencies 2.23 GHz and 5.38GHz.The optimized return loss is exhibited at feed length of 3.2 mm. Figure 4. Return Loss (S11)of FRCPA in mode -1(Swicthes ON)
522 Sharanagouda N Patil, Prof. P.V.Hunagund, Prof. R.M.Vani & Ravi M Hatti The return loss for the switchable slot FRCPA antenna in mode-2,i.e. when both the switches are OFF is given in the figure 5.The resonating frequency is at 2.63GHz. Figure 5. Return Loss (S11) of FRCPA in mode -2(Switches OFF) The 2D radiation pattern in mode-1 is given in the figure 6. Figure 6: 2D Radiation pattern in mode-1( at 3GHz) The 2D radiation pattern in mode-2 of the FRCPA is given in figure 7 at 3GHZ
Reconfigurable Patch Antenna for Software Defined Radio Application 523 Figure 7: 2D Radiation pattern in mode-2 (at 3GHz) The 2D radiation patterns are almost Omni-directional in both the modes with acceptable deviation in mode-2. The switches are located by using the optimization tool of the HFSS.The slot structure is etched by studying the current distribution in the basic FRCPA without slots. The figure 8 and 9 show the current distribution of the FRCPA antenna post optimization in mode -1 and mode-2 to get the desired resonant frequency. Figure 8: Current distribution of FRCPA in mode-1
524 Sharanagouda N Patil, Prof. P.V.Hunagund, Prof. R.M.Vani & Ravi M Hatti Figure 9: Current distribution in mode-2 IV. CONCLUSION A novel miniaturized frequency reconfigurable circular patch antenna with switchable slots in the radiating patch presented in this paper for frequency agility for software defined radio applications. The RF PIN diode from Infineon BAR 67-02V model was used for the design. The equivalent circuit model was considered for the design of the antenna. The return loss, 2D-radiation pattern and the current distribution of the FRCPA the antenna was also measured and plotted. The frequency agility of the antenna makes it a good choice for the SDR applications. The future work can investigate the FRCPA in multi mode and multi protocol standard designs for Cognitive Radio applications. REFERENCES [1] G. Villemaud, C. Decroze, F. Torres, T. Monediere and B. Jecko, "Multi-band antenna for mobile communication standards," 2002 9th International Symposium on Antenna Technology and Applied Electromagnetics, St. Hubert, QC, Canada, 2002, pp. 1-4. [2] W. Y. Sam and Z. Zakaria, "The investigation of the varactor diode as tuning element on reconfigurable antenna," 2016 IEEE 5th Asia-Pacific Conference on Antennas and Propagation (APCAP), Kaohsiung, 2016, pp. 13-14.
Reconfigurable Patch Antenna for Software Defined Radio Application 525 [3] J. Mitola and G. Q. Maguire, "Cognitive radio: making software radios more personal," in IEEE Personal Communications, vol. 6, no. 4, pp. 13-18, Aug 1999. [4] C.G. Christodoulou, "RF-MEMS and its applications to microwave systems, antennas and wireless communications," Proceedings of the 2003 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference - IMOC 2003. (Cat. No.03TH8678), 2003, pp. 525-531 vol.1. [5] W. M. Fathelbab, "Classes of reconfigurable band-reject filters realising constant absolute bandwidth in two distinct states," in IET Microwaves, Antennas & Propagation, vol. 9, no. 10, pp. 989-1003, 7 16 2015. [6] Y. Yang and Z. Xi, "Microwave Devices Simulation with Ansoft HFSS," 2007 8th International Conference on Electronic Measurement and Instruments, Xi'an, 2007, pp. 2-413-2-417. [7] H. A. Mohamed, H. B. El-Shaarawy, E. A. F. Abdallah and H. El-Hennawy, "Compact dual mode switchable BPF BSF using RF PIN diodes and DGS," 2013 Asia-Pacific Microwave Conference Proceedings [8] E. R. Kusumawati, Y. H. Pramono and A. Rubiyanto, "Design and fabrication of tunable microstrip antenna using photodiode as optical switching controlled by Infrared," 2013 IEEE International Conference on Communication, Networks and Satellite (COMNETSAT), Yogyakarta, 2013, pp. 55-58. [9] X. l. Yang, J. c. Lin, G. Chen and F. l. Kong, "Frequency Reconfigurable Antenna for Wireless Communications Using GaAs FET Switch," in IEEE Antennas and Wireless Propagation Letters, vol. 14, no., pp. 807-810, Dec. 2015. [10] Infineon RF PIN diode data sheet available online www.infineon.com Accessed on 06-02-2017.
526 Sharanagouda N Patil, Prof. P.V.Hunagund, Prof. R.M.Vani & Ravi M Hatti