Design and Performance Analysis of a Novel Elliptical Microstrip Patch Antenna Targeting Applications in ISM Band
Abstract. The growth of portable wireless communication devices has pushed researchers pay great attention to design miniature compact antennas. The most prized among miniature antenna choices is the microstrip patch antenna. These antennas have significant advantages such as conformability to host surface, light weight, low profile and easy installation. In this paper a novel design of a compact elliptical microstrip patch antenna is proposed for Industrial, Scientific and Medical (ISM) band (2.45GHz) applications e.g. Radio Frequency Identification (RFID) Applications. The proposed antenna consists of elliptical patch on FR 4 (PCB) substrate followed by partial ground at the back of the substrate. The overall size of the proposed antenna is 45x38 mm^sup 2^ It also compares the performance of the designed antenna for four different dielectric materials such as Dacron fabric (e^sub r^ 3) Dupont 951(e^sub r^ 7.8) Teflon (e^sub r^ 2.1) and Taconic RF 35P (e^sub r^ 3.5) material to investigate their characteristics and performance. After analysis on the different materials, Dacron showed the best performance among all.Keywords: ISM Band, Elliptical Patch Antenna, Substrate, Low Profile, Narrow band, Return Loss.(ProQuest: denotes formulae omitted.)1 INTRODUCTIONRFID stands for Radio Frequency Identification and is a term that descr ibes a system of identification (Bohn 2008).It is based on storing and remotely retrieving information or data as it consists of RFID tag, RFID reader and back end Database (Schwieren et al. 2009) It is given to the wireless, radio wave technology that allows for a small RFID chip to be embedded in any physical object and uniquely identified by an RFID reader. RFID systems span a wide spectrum of application areas which has become high demand in the recent years in many fields specially in smart dust, defense, clothes, navigation systems for the visually impaired, edible RFID tags, retail, travel, agriculture, etc. RFID is continuing to become popular because it increases efficiency and provides better service to stakeholders (Bohn 2008).The range of the RFID tags depends on their frequency. This frequency determines the resistance to interference and other performance attributes (Zeisel et al. 2006) The use/selection of RFID tag depends on the application; different frequencies are used on different RFID tags (Chen et al. 2011) Generally, there are four common bands for RFID systems. They are the Low frequency (LF) band of 125 kHz to 134 kHz, high frequency (HF) band for 13.56 MHz, Ultra high frequency (UHF) for 860MHz to 960 MHz and microwave (MW) band for 2.45 GHz or 5.8 GHz (Mokhtar et al. 2013) The microwave bands are popular than other RFID bands in many areas because of its high readable range, fast reading speed, large information storage capability and low cost.There is no perfect antenna for all the applications of RFID. It is the application that defines the antenna specifications(Tiang et al.2011) (Naji et al. 2013) (Lu et al. 2009) However, the demand for low cost and low profile antenna for RFID applications can be met by microstrip patch antennas. Elliptical microstrip patch antennas are the ones under consideration as their geometry presents greater potentials for a variety of electrically small low profile antenna applications. The elliptical shape has several advantages like providing larger flexibility in the design, more degrees of freedom compared to the circular geometry (Agrawal et al. 2011).In this paper an Elliptical microstrip patch antenna is proposed at 2.45 GHz (i.e. ISM band) on FR 4 (PCB) substrate. The outline of the paper is structured as the following. Section 2 describes the antenna geometry. Substrate materials selected are mentioned in section 3. Designed antennas with different permittivity are shown in section 4. The antenna performances are evaluated and compared in section 5 6. A conclusion is given in section 7.