纸基RFID包装箱标签天线设计,包装箱环境对RFID 标签天线的影响,图1 贴附RFD标签的包装箱示意图,图2 RFD标签的包装箱剖面图,介电常数r = 2. 5 纸质介质基板厚度为1mm,图3 天线的尺寸图,而RFID标签天线阻抗受包装箱内物品介电常数的影响, 阻抗值波动十分剧烈。因此, 为了与常见的RFID 标签芯片相匹配,图4r对天线电阻R天线的影响,图5 r对天线电抗X天线的影响,图6 RFID标签(1)结构侧面图,从图7和图8中可以看出, 采用新标签时, 当h= 2 mm 时, 新标签天线的电阻和电抗曲线较平缓, 对物品介电常数不敏感。波动范围在50 100之间。但RFID 标签IC的电阻较小( 20左右), 而标签天线电阻的波动范围( 50 100)仍然太大, 与RF ID标签芯片匹配存 在困难。,对标签天线( % )电抗X天线%的影响,对标签天线( # )电阻R天线# 的影响,图7,图8,为了进一步改善RFID 标签天线对物品介电 常数的适应性, 本文提出了把空气层和金属层面积扩大一倍,当h=2 mm 时, 新标签天线阻抗的电阻和电抗变化曲线平缓, 波动范围不超过5%。由此可见, 标签天线( % )的阻抗只与天线的结构和空气层厚度有关, 包装箱内的物品种类对其影响不大。,对标签天线( )电阻R天线%的影响,图10,图11,对标签天线( )电抗X天线 %的影响,由表1和表2可以看出, 在不同介电常数的物 品影响下, RFID标签天线(#)和标签天线(%的阻抗测量值均保持不变。其中, RFID 标签(%)天线电阻和电抗始终保持在20 和800 左右, 基本接近常用的RFID 标签芯片阻抗目标, 具有很高的应用价值。,表1 RFID标签天线( # )阻抗测量值,表2 RFID标签天线( % )阻抗测量值,Chipless RFID Tag Using Hybrid Coding Technique,In the proposed design of this paper, we emphasize a way to increase the coding efficiency in order to reach a high number of combinations with few resonators.,Fig. 1. Scatterers having various shape without ground plane: (a) “C”-likestructure, (b) rectangular SRR, (c) shorted dipole, (d) circular SRR. The stripwidth is 1 mm for all the resonators.,Table I presents the key parameters for each ECP,such as the 3 dB bandwidth and the RCS (Radar Cross Section)magnitude. Simulation results are obtained by using CST Microwave.Studio with plane wave excitation,TABLE I Q FACTOR AND LEVEL RESPONSE FOR VARIOUS ECP AT 3 GHz,Fig. 2. View of chipless tags (a) tag 1, (b) tag 2, (c) tag 3, (d) tag 5, (e) tag 6,(f) tag 7. Dimensions are given in Table II.,TABLE II TAG DIMENSIONS IN mm, AND ASSOCIATED TARGETED CODES,Fig. 3. Basic resonating element based on a metallic strip like-“C” structure,it was found in simulation that this angle has to be lower than .,Fig. 4. Simulated and modeled RCS amplitude of a “C” ECP for different gap values.,Fig. 5. Simulated and modeled RCS phase of a “C” ECP for different gapvalues.,its bandwidth is equal to the difference between both the peak and the dip frequencies,Fig. 10.(a)Absence/presencecoding technique introduced by Jalaly 8. (b)Frequency shift coding technique 13.,Fig.11.Constellationdiagram(a)forabsence/presence coding technique 7,(b) for frequency shift coding technique 11.,Fig. 12. Coding principle using both phase and frequency shift encoding.,Fig. 13. 2D Constellation diagram for hybrid technique combining phase deviation to frequency shift encoding.,Fig. 14. Measurement set-up using a VNA HP8720D in bi-static configuration.Antennas and tag are put inside an anechoic chamber.,Fig. 15. RCSmagnitude measurements for tag 1, 4 and 5.,Fig. 16. RCS phase measurements for tag 1, 4 and 5.,Fig. 17. RCS magnitude measurements for tag 1, 6 and 7.,Fig. 18. RCS phase measurements for tag 1, 6 and 7.,TABLE III HALF DEVIATION PHASE BANDWIDTH IN MHz AS A FUNCTION OF TAG CONFIGURATION,TABLE IV FREQUENCY OF THE RESONANCE PEAK IN MHz AS A FUNCTION OF TAG CONFIGURATION,3. Novel Chipless RFID Tagfor Conveyor Belt Tracking using Multi-Resonan Dipole Antenna,a linearly polarized UWB circular monopole antenna coupled to an orthogonally polarized novel dual multi-resonant dipole antenna.,gain of over 5 dB,a frequency signature,in the orthogonal polarization of the interrogation signal,Cross polar RCS corresponds with the return loss of the multi-resonant loop antenna,tag cost and as such, there are limitations that govern its use. Many low cost RFID applications will place the tagged items on a conveyer belt type system where the reader antenna is fixed and the transponder moves past the reader in a predictable way, or where the tagged item is stationary and the reader is in some sort of handheld device that can be positioned by the user,The interrogation signal is linearly polarized and the received signal is orthogonally polarized so that they are easily identifiable.,The reader generates a signal at frequency f1 and records the return signal in the orthogonal polarization and repeats the process at the next frequency f2 until the entire band of interest has been scanned.,a wide bandwidth, linear polarization, and consistent radiation pattern throughout the frequency band,reader and transponder antennas are aligned,an Omnidirectional pattern in the H-Plane and a doughnut shaped pattern in the E-Plane.,Fig 3 - Measured vs Simulated E and H Plane Radiation Pattern forcircularMonopole from Fig. 1 with R = 7mm,Since the endsection of the loop is small in length(/10)the loops act as folded dipole antennas which creates a strong linear polarization.,Fig 4 - MRDA Layout with Dimensions (mm),indicated in yellow in all figures, red indicates the top conductive layer,Fig 5 - Simulated vs Measured Return Loss for MRDA from Fig. 4 with Length=30mm,Width=5.8mm,FeedLength=14mm,Loopwidths=0.2mm,Loop gaps = 0.2 mm and Gap = 0.8 mm.,frequencies. However we wish to interrogate the transponder from the bore sight direction normal to the ground plane.,Fig 8 - E and H-Plane 2-D Radiation Pattern for dual MRDA fromFig. 8with Wm = 20 mm, LT = 10 mm, WT = 4.5 mm.,