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Fully printable polarization independent frequency domain chipless radiofrequency identification tag using the harmonic separation capability of Stepped Impedance Resonator is proposed. The data are encoded either using the magnitude or group delay of the backscattered signal. The data encoding capacity of the tag is enhanced using Frequency Shift Coding technique. Radiofrequency identification (RFID) is a wireless data capturing technique which uses RF waves for extracting the encoded data from remotely placed objects whose applications include pallet identification, road toll system, item tracking, fare collection system, and so forth. Chipless tags which require neither integrated circuit nor remote/self-empowerment are the current trend in the field of RFID. These printable chipless tags can also be used as a good alternative to the existing barcode technology [1]. Many fully passive printable frequency domain chipless RFID tags based on multiple scatterers are discussed in [2][3][4][5][6][7][8][9]. These scatterers act like radar targets and they will generate a unique spectral ID to encode data. Data encoding capacity, polarization, reradiation pattern, higher harmonic frequency separation/suppression, and readable range are the characteristics for the selection of the scatterers. The first RFID tag using multiple scatterrers was reported by Jalaly and Robertson [6] based on RF barcodes which are constructed with arrays of metallic microstrip dipoles on a dielectric substrate with ground plane. But many narrow bands were straddled with increase in bit encoding capacity. Polarization insensitive tag using nested circular rings is reported in [7] but the usable bandwidth is limited due to higher harmonic frequency. Independent control over fundamental and first harmonic frequency of k/4 (where k is the guided wave length) and k/2 stepped impedance resonator (SIR) structure is exploited to achieve high data encoding capacity with multiple bits per resonator [8]. But the tag is sensitive to the polarization of incident wave. A compact printable dual polarized chipless RFID system is presented in [9]. Here, two sets of slot resonators are placed with orthogonal polarizations to double the bit encoding capacity within the same frequency band. The readable range of the tag reported is only 5 cm and it suggests a less reliable technique of symmetric excitation for harmonic suppression. Two types of SIR-based tags are proposed in this article. Tag-I is polarization insensitive to the incoming waves and Tag-II is with enhanced data encoding capacity. Independent control over harmonic frequencies of SIRs enables wide band utilization to encode more data. Structural information in the tag can be decoded using magnitude or group delay of the backscattered signal. With Frequency Shift Coding (FSC), the surface coding density of Tag-I is 0.61 bits/cm 2 and of Tag-II is 1.22 bits/cm 2 . The proposed design provides a readable range of 40 cm without any additional detection algorithm. TAG DESIGN USING SIRSIRs ar...

A novel coplanar waveguide fed compact dual-band antenna for 2.5/5.7 GHz applications is presented in this paper. The above characteristics are obtained by carefully optimizing the slotted ground planes and meander short placed between the signal strip and one of the lateral ground planes. The proposed antenna has been designed on a substrate with dielectric constant 4.4, thickness 1.6 mm, and it occupies a small area of 18.2 × 20 mm 2. The experimental analysis shows 2 : 1 VSWR bandwidth up to 150 MHz and 370 MHz for 2.5 GHz and 5.7 GHz, respectively. Antenna radiation characteristics, including return loss, radiation pattern, radiation efficiency and gain are also validated with numerical simulation and experimental measurements.