Ferran Paredes

Multiband Printed Monopole Antennas Loaded With OCSRRs for PANs and WLANs

Multiband printed monopole antennas loaded with open complementary split-ring resonators (OCSRRs) are presented. The OCSRRs, modeled as parallel LC resonant tanks, act as high-impedance elements at their resonance frequencies, and different effective λ/4 sections can be achieved in the monopole by placing them at proper locations. Thus, the first working frequency is related to the length of the monopole, while the additional bands are controlled by the resonance frequencies of the OCSRRs. Moreover, the proposed antennas present monopolar radiation characteristics at all the operation bands. Two prototypes are designed, manufactured and measured: 1) a single-loaded OCSRR dual-band printed monopole antenna covering the Bluetooth and IEEE 802.11a/b/g/n bands (2.40-2.48 and 5.15-5.80 GHz, respectively); and 2) a triband prototype based on the same design, but with an additional OCSRR designed to also cover the IEEE 802.11y frequency band (3.65-3.70 GHz). Both antennas are printed on a single-layer of a low-cost substrate, resulting in very compact designs.

Dual-Band Impedance-Matching Networks Based on Split-Ring Resonators for Applications in RF Identification (RFID)

This paper is focused on the design of dual-band impedance-matching networks of interest in RF identification (RFID) systems. By cascading an impedance-matching network between the chip and antenna, the performance of the RFID tags can be improved. The main aim of this study is to demonstrate the possibility of designing such networks by means of split-ring resonators coupled to microstrip transmission lines. These resonators are especially useful in this design since their equivalent circuit substantially simplifies the parameter calculation of the matching network. Dual-band conjugate matching at two different frequencies, f1 = 867 MHz and f2 = 915 MHz, corresponding to the assigned bands for UHF RFID in Europe and the U.S., respectively, is demonstrated. The main difficulty for the synthesis of these dual-band matching networks relies on the proximity of f1 and f2. Although the chip impedance cannot be considered a design parameter, the network design can be alleviated by allowing certain flexibility in the antenna stage. The fabricated prototype, a dual-band impedance-matching network based on split-ring resonators and loaded with a slot antenna, was characterized by measuring its reflection coefficient. The results reveal that conjugate matching at the above-cited frequencies for the chip impedance under consideration is achieved.

Dual-Band UHF-RFID Tags Based on Meander-Line Antennas Loaded With Spiral Resonators

The purpose of this letter is to implement dual-band tags for ultrahigh-frequency (UHF) radio frequency identification (RFID) applications operative in Europe and the US. Since the regulated bands of UHF-RFID in Europe (867 MHz) and the US (915 MHz) are close, broadband tags might be also considered. However, it is demonstrated in this letter that the performance of dual-band tags designed to operate at the frequency bands of interest is superior to that of broadband (monoband) tags. A meander-line antenna (MLA) has been considered for tag implementation. The dual-band functionality is achieved through a perturbation method consisting of coupling an electrically small resonator [a two-turn spiral resonator (2-SR)] to the antenna. The analysis, design, and fabrication of a dual-band UHF-RFID tag has been carried out. The measured performance of the fabricated prototype is in good agreement with theory. Measured read ranges of 6 and 8 m at the European and US frequency bands, respectively, have been obtained.

Printed Magnetoinductive-Wave (MIW) Delay Lines for Chipless RFID Applications

A novel fully passive and electromagnetic chipless radiofrequency identification (RFID) system is proposed. The system is based on printed tags implemented with magnetoinductive-wave (MIW) delay lines. Such lines are composed of a periodic array of coupled square split ring resonators (SSRRs) and propagate slow waves. The tag is codified by introducing reflectors (which provide the identification signature) between the elements of the array. When the tags are interrogated with a pulse in time domain, they produce replicas at the positions where the reflectors are placed. Thanks to the slow group velocity of the MIW delay line, the replicas of the original pulse are not overlapped in time domain and can be demodulated, thus providing the identification code of the tag. The design considerations to implement these chipless tags are studied in the present work. Moreover, a complete set of codified MIW lines for a two-bit system is designed, manufactured and measured. The reported experimental results validate the proposed approach.

Fundamental-Mode Leaky-Wave Antenna (LWA) Using Slotline and Split-Ring-Resonator (SRR)-Based Metamaterials

A new composite right/left-handed (CRLH) slotline leaky-wave antenna (LWA) is proposed. The antenna, implemented by loading a slotline with split-ring resonators (SRRs), is designed to exhibit a balanced dispersion relation, with a continuous transition between the left-handed and the right-handed bands at 2.5 GHz. Since the periodicity of the structure is much less than a wavelength, the proposed LWA belongs to the family of quasi-uniform LWAs, and it radiates from the fundamental mode (contrary to periodic LWAs). Measured and simulated radiation patterns, gain, and scanning angle are reported for a 17-cell LWA. The experimental results demonstrate the potential of the LWA to continuously radiate from backward (- 50°) to forward (+60°) scanning angles, with maximum gains of 7.1 and 11.3 dB in the left- and right-handed bands, respectively, and specular radiation patterns.

Design and Synthesis Methodology for UHF-RFID Tags Based on the T-Match Network

A new systematic methodology for the design of T-match based UHF-RFID tags is proposed. The great majority of commercial UHF-RFID tags are based on dipole antennas using a modification of a T-match network. The literature contains examples of models that describe the T-match, but they are not sufficiently accurate to synthesize the tag geometry. Using the proposed methodology, a global band UHF-RFID tag based on a folded dipole antenna and matched to the RFID integrated circuit by means of a T-match network is designed and fabricated. Very good agreement between the measured and simulated read range is achieved within the entire UHF-RFID band, which reveals that the proposed method is amenable for accurate analysis and synthesis of T-match based UHF-RFID tags.

Analysis of the Split Ring Resonator (SRR) Antenna Applied to Passive UHF-RFID Tag Design

An electrically small planar passive UHF-RFID tag based on an edge-coupled split ring resonator (EC-SRR) antenna is presented in this work. In order to explore the potentiality and limitations of the SRR antenna and to aid the tag design, an analytical study of the SRR radiation properties at its fundamental resonance is presented for the first time. Radiation resistance, efficiency, polarization, bandwidth, and impedance matching with the radio-frequency identification (RFID) application-specific integrated circuit (ASIC) are treated in the study. Based on such analysis, the tag design process is presented, and a tag prototype of size 30 mm × 30 mm (λ0/11 × λ0/11) is designed to operate in the North-American UHF-RFID band (902-928 MHz) and manufactured. The measured read range is in good agreement with the simulation and reaches 9.3 m at 911 MHz. The tag also features a mitigation of the blind spots, providing a minimum measured read range of 4.2 m.

On the Radiation Properties of Split-Ring Resonators (SRRs) at the Second Resonance

The radiation properties of split-ring resonators (SRRs) at their second resonance frequency are studied for the first time in this work. In particular, the electric and magnetic dipole moments of the edge-coupled SRR are calculated analytically under the assumption of strong coupling between the internal and external rings. Based on these results, the radiation resistance and the radiation efficiency are obtained theoretically. Electromagnetic simulations of the structure reveal that there is very good agreement with the theoretical predictions, pointing out the validity of the proposed analysis. As a proof of concept, an SRR antenna prototype is designed and fabricated. Experimental data are in good agreement with the theoretical and simulated results, and demonstrate the validity of the SRR working at its second resonance frequency as a radiating element.

Multistate Multiresonator Spectral Signature Barcodes Implemented by Means of S-Shaped Split Ring Resonators (S-SRRs)

Spectral signature barcodes functional at the

An impedance matching method for optical disc-based UHF-RFID tags

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