A Universal Printed Antenna for UHF RFID Applications

In this paper, a printed rectangular monopole anten na is designed for RFID (Radio Frequency Identification) reader applications. The antenna is designed to operate at a frequency of 860 MHz to 960 MHz allocated for UHF RFID universal (worldwide) band. The antenna simulation is analyzed using 3D EM simulator, FEKO Software. The result of parameters such as radiation pattern, reflection coefficient and gain are also discussed. The propos ed antenna is simple in design and fair in size. Keyword: printed rectangular monopole antenna, RFID, UHF, radiation pattern, return loss


INTRODUCTION
Radio Frequency Identification (RFID) is a form of wireless communication that uses radio waves to identify or track objects. These transmissions are of unique serial numbers or codes. This is known as a contactless technology whereby the tag not need to be manually touched or wired. Now RFID finds many applications in various areas such as electronic toll collection, asset identification, retail item management, access control, animal tracking and vehicle security.
The common frequency used by RFID are low frequency (125-134 kHz) , high frequency(13.56 MHz), ultra high frequency , and microwave frequency .Radio waves behave differently at each of these frequencies with advantages and disadvantage associated with using each frequency band. RFID system consists of radio frequency transponders (tags), radio frequency transceivers (reader), and a host computer. The antennas for RFID systems also play a crucial role in the continuous development of this technology; it is @ IJTSRD | Available Online @ www.ijtsrd.com | Volume -2 | Issue -5 | Jul-Aug 2018 In this paper, a printed rectangular monopole antenna Frequency Identification) reader applications. The antenna is designed to operate at a frequency of 860 MHz to 960 MHz allocated for UHF RFID universal (worldwide) band. The antenna simulation is analyzed using 3D EM simulator, FEKO Software. The result of the antenna parameters such as radiation pattern, reflection coefficient and gain are also discussed. The proposed antenna is simple in design and fair in size.
printed rectangular monopole antenna, RFID, UHF, radiation pattern, return loss Radio Frequency Identification (RFID) is a form of wireless communication that uses radio waves to identify or track objects. These transmissions are of unique serial numbers or codes. This is known as a contactless technology whereby the tag or item does not need to be manually touched or wired. Now RFID finds many applications in various areas such as electronic toll collection, asset identification, retail item management, access control, animal tracking and The common frequency used by RFID are low 134 kHz) , high frequency(13.56 960 MHz), and 5.8 GHz).Radio waves behave differently at each of these frequencies with age associated with using each frequency band. RFID system consists of radio frequency transponders (tags), radio frequency transceivers (reader), and a host computer. The antennas for RFID systems also play a crucial role in this technology; it is the most important components in the optimization of the signal data to spread out into the air.
Printed monopole antenna is one of the most suitable antennas for achieving large bandwidth and omnidirectional radiation pattern. Pr antennas are new version of which the ground plane below the patch is etched out. It gives wider bandwidth. Several printed monopole antenna configurations have been proposed and such antennas have been designed for v using different simulation software.
In this paper, a single band rectangular shaped printed monopole antenna for RFID reader application is designed to resonate on Ultra High Frequency (UHF) universal band of 860-960 MHz. The theoret simulations are performed using FEKO Software.  (1)

II. ANTENNA DESIGN
Effective length, L eff= Length extension, Where; h = substrate thickness Actual patch length, Ground plane extension Lg ≠ Wg Lg = 6h + L (6) Wg = 6h + W Where; h = substrate thickness The feed line for the printed rectangular monopole antenna determines to be fed for 50 ohm for line impedance (Zo). The length and width for the feed line can be calculated using equations (5), (8) and (9).
Feed width, Where; h = substrate thickness Zo = line impedance Table I shows the results calculation of printed rectangular monopole antenna operated at UHF band.

Figure3.SimulatedAntenna Design (a) Front View (b) Back View
The simulated reflection coefficient of the proposed antenna is shown in Figure4. In order to get a better performance of an antenna, the reflection coefficient should be less than -10 dB. The simulated reflection coefficient is -10 dB on 850-970 MHZ at over the frequency range of RFID Universal UHF band (860-960 MHz).The obtained bandwidth is 100 MHz.

Figure4. The Reflection Coefficient of the Antenna
The simulation result of the proposed antenna gain is shown in Figure5 Another useful measurement describing the performance of antenna is the radiation pattern. antenna radiation pattern is defined as a mathematical function or graphical representation of the radiation properties of the antenna as a function of space coordinates.Figure6shows the radiation pattern at Phi=0 degree and the Figure7 shows pattern at Phi=90 degree for the designed antenna at 960 MHz.

IV. CONCLUSION
The printed rectangular monopole antenna becomes a rapidly growing area of research. A printed rectangular monopole antenna was designed and simulated in this paper. The printed rectangular monopole antenna has -10 dB at 850 moderate gain of over 1.3 dBi and omnidirectional radiation pattern. Thus this printed rectangular monopole antenna can be used for UHF RFID reader at worldwide frequency band of 860-960 MHz.