TAILIEUCHUNG - Development and Implementation of RFID Technology Part 3

Tham khảo tài liệu 'development and implementation of rfid technology part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Design Fundamentals and Advanced Techniques of RFID Antennas 51 With the increasing frequency the electric and magnetic fields are no more independent from each other but become incorporated described by the Maxwell equations where the time-varying electric field leads to the space-varying magnetic field and vice versa. And they move in the air carrying the power. 3. Conjugate impedance matching The impedance matching condition has been addressed very essential regarding the quality of the RFID system with the power received by the tag and reader. In Figure 2 a simplified transmission line models the linkage of the reader antenna and the tag with the chip. The transmission line circuit is connected to the input impedance of the reader antenna and the tag and it is ideal for the overall circuit to be matched to both the source and load. However in practice the impedance matching for the reader and the tag is split. And for the reader alone the impedance matching is made to remove the reflection to the antenna from the feeding circuit. Simultaneously as just for the tag the impedance of the antenna should be matched with that of the chip. Though the matching problems of the reader and the tag are treated separately the schemes are the same. Hence throughout this section we talk about the impedance matching techniques Shunt stub matching Inductive loop matching and Nested slot matching for only the tag. Shunt stub T- matching The chip has the capacitive impedance which has the negative imaginary term. In order to have the best tag antenna efficiency the input impedance of the antenna should have the inductive reactance which cancels the capacitance reactance of the chip when they are connected. Fig. 6. Inductive stub matching of the antenna against the capacitive chip 52 Development and Implementation of RFID Technology As an example the chip has the negative reactance -j100 in Figure 7. For the total input impedance of the tag to have only the real term 70Q the .

TÀI LIỆU LIÊN QUAN
69    272    11
TỪ KHÓA LIÊN QUAN
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.