MEE08:29 DESIGN AND FABRICATION OF A MICRO-STRIP ANTENNA FOR WI-MAX APPLICATIONS Tulha Moaiz Yazdani Munawar Islam This thesis is presented as part of Degree of Master of Science in Electrical Engineering Blekinge Institute of Technology October 2008 Blekinge Institute of Technology School of Engineering Department: Signal Processing Supervisor: Dr. Mats Pettersson Examiner: Dr. Mats Pettersson - ii - UAbstract Worldwide Interoperability for Microwave Access (Wi-Max) is a broadband technology enabling the delivery of last mile (final leg of delivering connectivity from a communication provider to customer) wireless broadband access (alternative to cable and DSL). It should be easy to deploy and cheaper to user compared to other technologies. Wi-Max could potentially erase the suburban and rural blackout areas with no broadband Internet access by using an antenna with high gain and reasonable bandwidth Microstrip patch antennas are very popular among Local Area Network (LAN), Metropolitan Area Network (MAN), Wide Area Network (WAN) technologies due to their advantages such as light weight, low volume, low cost, compatibility with integrated circuits and easy to install on rigid surface. The aim is to design and fabricate a Microstrip antenna operating at 3.5GHz to achieve maximum bandwidth for Wi-Max applications. The transmission line model is used for analysis. S-parameters (S11 and S21) are measured for the fabricated Microstrip antenna using network analyzer in a lab environment. The fabricated single patch antenna brings out greater bandwidth than conventional high frequency patch antenna. The developed antenna also is found to have reasonable gain. - iii - - iv - UAcknowledgement It is a great pleasure to express our deep and sincere gratitude to our supervisor Dr. Mats Pettersson, Ph.D, Senior Lecturer of Blekinge Institute of Technology. Whose extreme patience made this dissertation possible His wide knowledge and his logical way of thinking have been great value for us. He provided us always energetic and devoted supervision and guidance throughout the thesis work. He always very much cooperative and helped us whenever we needed, in spite of his busy schedule. We would also like to thanks our colleagues for whom we have regard, and wish to extend our warmest thanks to all those who have helped us with our work. And finally special dedication to our families whom help and support for us in these years. We simply could not done it without them and hope that someday we can make it up to them. - v - UContents Chapter 1 Wireless communication Technology 1.1 Introduction 1.2 History 1.3 Basic Communication System 1.4 Different Mobiles Generation 1.5 WLAN(Wireless Local Area Network) 1.6 Bluetooth 1.7 Wi-Max 1.8 Importance of Antenna in Wireless System 1.9 Future of Wireless Technology Chapter 2 Antenna Essentials 2.1 Antenna Definition 2.2 Antenna Radiation 2.3 Friis Transmission Equation 2.4 Radiation Field Region around Antenna 2.5 Antenna Parameters 2.6 Far Field Radiation from Hertzian dipole Chapter 3 Microstrip Patch Antenna 3.1 Introduction 3.2 Feeding Methods 3.3 Comparison of Different Feed Methods 3.4 Methods of Analysis 3.5 Bandwidth & Quality Factor of Microstrip Antenna 3.6 Advantages & Disadvantages Chapter 4 Result and Measurement 4.1 Design Procedure 4.2 Measurement and Result 4.3 Conclusion - vi - UAcronyms CDMA Code Division Multiple Access EDGE Enhanced Data for GSM Evolution FCC Federal Communication Commission FR-4 Flame Resistance-4 GSM Global Systems for Mobile iDEN integrated Digital Enhanced Network IEEE Institute of Electrical and Electronic Engineering ISM Industrial, Scientific and Medical LAN Local Area Network MAN Metropolitan Area Network MBWA Mobile Broadband Wireless Access MMIC Monolithic Microwave Integrated Circuit NLOS Non Line of Sight OFDM Orthogonal Frequency Division Multiplexing PAN Personal Area Network PCMCIA Personal Computer Memory Card International Association PDA Personal Digital Assistance R.L Return Loss SCDMA Synchronous CDMA SMA Sub Miniature version A TACS Total Access Communication System UMTS Universal Mobile Telecommunication System VoIP Voice over Internet Protocol WAN Wide Area Network WCDMA Wideband CDMA WiDEN Wideband iDEN WLAN Wireless Local Area Network WMAN Wireless Metropolitan Area Network - vii - Chapter 1 Wireless Communication Chapter 1 Wireless Communication 1.1 Introduction Telecommunication is assisted transmission of signals over a distance for the purpose of communication. In early time this may involve the use of smoke signals, drums, semaphore (an apparatus for conveying information by means of visual signals, as a light whose position may be changed), flags or heliograph (a device for signaling by means of a movable mirror that reflects beam of light, esp. sunlight, to a distance). In modern times, telecommunication typically involves the use of electronic transmitters such as the telephone, television, radio or computer [1]. Radio or wireless communication means to transfer information over long or short distance without using any wires. Million of people exchange information every day using pager, cellular, telephones, laptops, various types of personal digital assistants (PDAS) and other wireless communication product [2]. The thesis aims to design an antenna model using IEEE given frequency band and to determine its various parameters, that how we can improve it using the frequency of 3.5GHz. This thesis investigates the use and design of a rectangular patch antenna having a thin metallic strip placed a fraction of wavelength above the ground surface with coaxial feed system. This antenna is found to be suitable for IEEE 802.16d Wi- Max application. 1.2 History Guglielmo Marconi invented the wireless Technology in 1896 (The actual invention of radio communications more properly should be attributed to Nikola Tesla, who gave a public demonstration in 1893. Marconi’s patents were overturned in favor of Tesla in 1943 [ENGE00]) [3]. In 1901 Guglielmo Marconi sent telegraphic signals across the Atlantic Ocean from Cornwall to St.Johan’s Newfoundland, it covers a distance of 1800 miles. His invention allowed two parties to communicate by sending each other alphanumeric characters encoded in an analog signal [3]. Over the last century, wireless technologies have led towards the radio, television, Paging system, Cordless phone, Mobile telephone, Satellite and wireless networks. This advancement in wireless communication is widely deployed and used through out the world in last four decades [4]. The first practical standard of cellular communication named first Generation (1G) was deployed and used in 1980. 1G uses the analog signal for communication of voice calls only. In the beginning of nineteen’s century this standard changed to digital second Generation (2G) and to the end of nineteen’s century it was still digital but better bandwidth and good quality of signal in third Generation (3G), Now a days industries are working on fourth Generation (4G) [5]. In 1994, Ericsson Telecomm Company introduces a portable device named Bluetooth. The aim of this device was to unite the computer and telecommunication industry [6]. After this invention, Ericsson realized that product had huge potential worldwide, and from the Bluetooth special Interest group, which now a days includes over thousand of companies from around the world [6]. Chapter 1 Wireless Communication 1.3 Basic Communication System The block diagram of communication system is shown below, Fig: 1.1 Block diagram of digital communication system [7] I. The input data which can be any shape like voice, video, images. II. The input data is applied to the channel encoder, this portion changing the data into very suitable manners like A-D converter and then transmit the data. III. Channel is actually a medium (wired or wireless) between transmitter and receiver. In channel part there are two inputs one is coming from transmitter and other is channel noise (unwanted signal or information is called noise). Thus the resultant data at the output of channel is altered. IV. The altered data at the output of channel is received by the receiver. The received data is decoded to reconstruct an original data transmitted by transmitter. V. Finally the reconstructed data is forward to the destination. 1.3.1 Concept of Cellular System A cellular telephone system provides a wireless connection to the Public Switch Telephone Network (PSTN) for any user location within the radio range of the system [8].The limited capacity of the first mobile radio-telephone services was related to the spectrum used, not much sharing and a lot of bandwidth dedicated to a single call [9]. It provided the good coverage but impossible to reuse the same frequency due to interference. The cellular concept addressed many of the shortcomings of first mobile telephones like frequency reuse and wasted spectrum allocated to a single user. Fig: 1.2 Cellular Network Architecture [9] Chapter 1 Wireless Communication In 1968 Bell Labs proposed the cellular telephone concept to the Federal Communications Commission (FCC). Then it was approved, it used the spectrum frequency of 845MHz to 870-890MHz band [9]. In 1960 to 1970’s Bell working on mobile system give the concept of dividing the coverage area into small cells, each of reused portions of spectrum. This leads to greater system infrastructure. It is the hexagon [4] geometry cell shape. Fig: 1.3 Frequency Reuse in cellular Networks [4] In above Fig 1.3 shows cellular frequency reuse concept. Cells with the same letter use the same set of frequencies. A cell cluster is outlined in bold and replicated over the coverage area. In the example, cluster size, N, is equal to seven, and the frequency reuse factor is 1/7 since each cell contains one-seventh of the total number of available channels [4]. FCC finally allocated the 40MHz spectrum in the 800MHz band, where a signal channels occupies 30 KHz bandwidth for Advance Mobile Phone System (AMPS) [10]. Cellular system is widely popular across the world due to its portability, flexibility, quality, bandwidth, and specially user friendly.