RFID Reader Antenna And Extended Microstrip Antenna Design Placed On The Roadside Parking Space

Radio frequency identification(RFID) is a technology which completes the non-contact target automatic recognition by a space of electromagnetic waves coupled and ultimately gets useful information of the target object. RFID technology has many advantages, such as identifying the target quickly, multi-target recognizable simultaneously and strong anti-interference ability etc, so RFID systems are widely used in many areas such as transportation, logistics and agriculture. In recent years, as the internet of things becomes an important part of a new generation of information technology and RFID technology is one of the three key technologies of the internet of things. RFID technology attracts more and more people's attention and is considered one of the most promising technologies in twenty-first century. At present, the domestic applications and researches of RFID technology in the low and high frequency are mature while there is a great development potential in the 2.45 GHz microwave band. Antenna, which acts as a device for receiving and transmitting information in a wireless communication system, plays a very important role in an RFID system and its performance will directly affect the subsequent processing of the signal. Therefore, it has practical significance to conduct in-depth research for antenna designing.Firstly, this paper makes a brief introduction of the history of RFID development and the state of the art and abroad, and then introduces the basic theories of RFID technology and microstrip antenna to illustrate the composition, working principle and classification of RFID system as well as basic structure, analytical method, and performance parameters of microstrip antenna.Secondly, a general design method of a monopole RFID reader antenna at 2.45 GHz is given based on the theory of microstrip antenna, which used in vehicle inspection device. The antenna operates in microwave band. By simulating and optimizing of structural parameters of HFSS, the effective bandwidth of final design reaches 280 MHz(2.27 GHz-2.55 GHz), the gain close to 2 dBi, and it covers WiFi / WLAN / IEEE 802.11 2.4 GHz(2.412 GHz- 2.484 GHz) and Bluetooth band. Therefore, the antenna can be well used in WLAN.Finally, based on the microstrip antenna research, a WLAN/Wi MAX dual-band microstrip antenna which resonates at 2.45 GHz and 3.5 GHz is given. By simulation and optimization of structural parameters of HFSS, the effective bandwidth of antenna is 130 MHz(2.35 GHz-2.49 GHz) at 2.45 GHz and 300 MHz(3.36 GHz-3.66 GHz) at 3.5 GHz. This dual-band antenna has good impedance matching and radiation pattern in the two center frequencies.