X.-W. Shi

An Enhanced Binary Anti-Collision Algorithm of Backtracking in RFID System

AN ENHANCED BINARY ANTI-COLLISIONALGORITHM OF BACKTRACKING IN RFID SYSTEMX.-L. Shi, X.-W. Shi, Q.-L. Huang, and F. WeiNational Key Laboratory of Antennas and Microwave TechnologyXidian UniversityXi’an 710071, P. R. ChinaAbstract—On the base of the binary search algorithm of backtrack-ing, an enhanced binary anti-collision search algorithm for radio fre-quency identification (RFID) system is presented in this paper. Withthe method of transferring the collision bit in place of the ID of thetag, the proposed algorithm can improve identification efficiency sig-nificantly. Mathematical simulation result shows that compared withthe binary search algorithm, dynamic binary search algorithm and thebinary search algorithm of backtracking, the proposed algorithm out-performs the three algorithms previous when handling multiple RFIDtags simultaneously.1. INTRODUCTIONRadio frequency identification (RFID) system is a contact-lessautomatic identification system. Now it has received much attention inmany industries like manufacturing companies, material flow systems,etc. Compared with the barcode, a RFID system has many merits asfollows [1]:A. The information stored in a tag is much larger than that in abarcode.B. The information stored in tags can be reprogrammed and tags canbe used repeatedly.C. A tag has a much longer life than a barcode especially when theworking condition is extremely bad.D. When there is a barrier in front of a barcode, the barcode can notbe read by a reader, but a tag can be read due to the differentworking styles.

Novel Wideband Bandpass Filter Integrating HMSIW with DGS

In this paper, a novel method is proposed to design wideband bandpass filters with compact size. Combining half mode substrate integrated waveguide (HMSIW) and periodic dumbbell-shaped defected ground structure (DGS), two compact wideband bandpass filters with different HMSIW-microstrip transitions are fabricated and measured. The filters are found to possess wide passband bandwidth and compact size. Good agreement between the measured and simulated results demonstrates the validity of this technique.

A Tunable Bandpass Filter with Switchable Bandwidth

A novel bandpass filter with tunable center frequency and switchable bandwidth is presented in this paper. This work is devoted to demonstrate a new approach to tune bandwidth of filters by changing the size of perturbation patch of dual-mode resonator. The proposed filter mainly consists of a dual-mode ring resonator, four varactor diodes and a pin diode. The center frequency could be conveniently tuned from 1.25 GHz to 1.45 GHz, and the fractional bandwidth can be tuned in two discrete states 8% and 12%, respectively. Comparison of the measured and simulated results shows good agreement about center frequency and bandwidth.

Compact UWB Bandpass Filter with Narrow Notch-Band and Wide Stop-Band

This paper presents a compact ultra-wideband (UWB) band-pass filter (BPF) with a sharply rejected notch-band and wide stop-band. The proposed UWB BPF is realized by cascading two interdigital hairpin resonator units, a spiral slot, a semicircle defected ground structure (S-DGS) and a semicircle stepped-impedance shunt stub (S-SISS). The spiral slot is studied and adopted to introduce a notched band. An S-DGS and an S-SISS are cascaded in order to suppress the spurious in stopband. Good insertion/return losses and high out-of-band rejections are achieved as demonstrated in both simulation and experiment.

Design of Compact UWB Power Divider with One Narrow Notch-Band

This paper presents a compact ultra-wideband (UWB) power divider (PD) with a sharply rejected notch-band. The proposed UWB power divider is realized by cascading one conventional Wilkinson power divider and two folded shunt quarter-wavelength short-circuited stubs, one spiral slot in two symmetrical output ports. The spiral slot is studied and employed to generate the desired notched band. Good insertion/return losses and high notch-band rejection are achieved as demonstrated in both simulation and experiment.

Design of a Compact UWB Bandpass Filter with Defected Ground Structure

A compact ultra-wideband (UWB) band-pass filter (BPF) with improved upper-stopband is proposed in this paper. The proposed UWB BPF is composed of two cascaded interdigital hairpin resonator units and two same semicircle defected ground structures (S-DGS). Interdigital hairpin resonator unit with different coupling and S-DGS with different dimensions are theoretically analyzed. The working frequency of the proposed UWB BPF is 3.1–10.6 GHz and upper-stopband with 15 dB attenuation is up to 18 GHz. Finally, measured results are presented, which are in good agreement with the simulation results.

A Tunable Bandpass Filter with Constant Absolute Bandwidth

A novel tunable bandpass filter with constant absolute bandwidth is presented in this paper. Introducing a mixed electric and magnetic coupling structure and a new external coupling scheme, nearly constant absolute bandwidth is maintained across the tuning range. Theoretical analysis and design approach are demonstrated. The proposed filter is designed with a frequency coverage of 0.78–1.08 GHz and constant 3-dB bandwidth of 50 MHz over the tuning range. The experimental results show good performance of the filter and validate the design concept.

A Dual Passband Filter using Hybrid Microstrip Open Loop Resonators and Coplanar Waveguide Slotline Resonators

A novel dual passband filter using hybrid microstrip open loop resonators and coplanar waveguide (CPW) slotline resonators is proposed. With the CPW feeding structure, the center frequencies and 3-dB fractional bandwidth (FBW) can be achieved relatively independently. The external quality factor and coupling coefficient of the resonators are obtained. The proposed dual passband filter has center frequencies of 2.44 GHz and 3.5 GHz, which could be appropriately used for wireless local area networks (WLAN) and WiMax. Good agreement between simulated and measured results is demonstrated.

A Novel Planar 180° Out-of-Phase Power Divider for UWB Application

A novel planar out-of-phase (180°) power divider with ultra wideband behavior is presented. The proposed power divider employs a T-junction in output ports combined with a slotline and a microstrip line accompanied by wideband microstrip to slotline transitions in order to achieve an out-of-phase signal division over a large frequency range. With the help of the metal pin connected to the system ground plane, the impedance bandwidth improved from 85% to about 133%. The simulated and measured results show that the proposed power divider has equal power division with high stability of phase, a low insertion loss and good return loss at the three ports across the band 3.1 GHz to more than 10.6 GHz.

A Novel CSRRs DGS as Lowpass Filter

A novel complementary split-ring resonators (CSRRs) DGS has been investigated theoretically and experimentally. The proposed DGS provides excellent performance in terms of double resonant property, ripple in the pass band, sharp selectivity at the cut-off frequency and spurious free wide stop band. A LPF using the proposed DGS unit is fabricated and three cascaded DGSs are employed in another LPF to obtain very wide reject band. The measured results illustrated the excellent performance.