Mohammed R. AlShareef

Metamaterial Particles for Electromagnetic Energy Harvesting

Antennas developed for electromagnetic field energy harvesting, typically referred to as rectennas, provide an alternative electromagnetic field energy harvesting means to photovoltaic cells if designed for operation in the visible frequency spectrum. Rectennas also provide energy harvesting ability or power transfer mechanism at microwave, millimeter and terahertz frequencies. However, the power harvesting efficiency of available rectennas is low because rectennas employ traditional antennas whose dimensions is typically proportional or close to the wavelength of operation. This invention provides a device for electromagnetic field energy harvesting that employs a plurality of electrically-small resonators such as split-ring resonators that provide significantly enhanced energy harvesting or energy collection efficiency while occupying smaller footprint. The invention is applicable to electromagnetic energy harvesting and to wireless power transfer.

Electrically small resonators for energy harvesting in the infrared regime

A novel structure based on electrically small resonators is proposed for harvesting the infrared energy and yielding more than 80% harvesting efficiency. The dispersion effect of the dielectric and conductor materials of the resonators is taken into account by applying the Drude model. A new scheme to channel the infrared waves from an array of split ring resonators is proposed, whereby a wide-bandwidth collector is utilized by employing this new channeling concept.

Electrically small particles combining even- and odd-mode currents for microwave energy harvesting

We present a structure composed of an ensemble of electrically small resonators for harvesting microwave energy. A flower-like structure composed of four electrically small split-ring resonators (SRRs) arranged in a cruciate pattern, each with a maximum dimension of less than λo/10, is shown to achieve more than 43% microwave-to-alternating current conversion efficiency at 5.67 GHz. Even- and odd-mode currents are realized in the proposed harvester to improve the efficiency and concurrently reduce the dielectric loss in the substrate. An experimental validation is conducted to prove the harvesting capability.

A Novel L-Shape Ultra Wideband Chipless Radio-Frequency Identification Tag

A novel compact dual-polarized-spectral-signature-based chipless radio-frequency identification (RFID) tag is presented. Specifically, an L-shape resonator-based structure is optimized to have different spectral signatures in both horizontal and vertical polarizations, in order to double the encoding capacity. Resonators’ slot width and the space between closely placed resonators are also optimized to enhance the mutual coupling, thereby helping in achieving high-data encoding density. The proposed RFID tag operates over 5 GHz to 10 GHz frequency band. As a proof of concept, three different 18-bit dual-polarized RFID tags are simulated, fabricated, and tested in an anechoic chamber environment. The measurement data show reasonable agreement with the simulation results, with respect to resonators’ frequency positions, null depth, and their bandwidth over the operational spectrum.

Design of UWB chipless RFID tags using 8-bit open circuit stub resonators

This article proposes the design of a chipless ultra-wideband (UWB) radiofrequency identification (RFID) tag. The proposed structure consists of two modified circular disc monopole antennas and eight-bit open circuit (OC) stub resonators. This tag can be used to encode the incident signals in the frequency range 4-8 GHz. The proposed RFID tag elements are characterized using a full wave simulation program. Complete RFID system is modeled and time domain characteristics of the pulse received at the receivers antenna is studied.

A High-Density L-Shaped Backscattering Chipless Tag for RFID Bistatic Systems

Chipless radiofrequency identification (RFID) technology is very promising for sensing, identification, and tracking for future Internet of Things (IoT) systems and applications. In this paper, we propose and demonstrate a compact 18-bit, dual polarized chipless RFID tag. The proposed tag is based on L-shaped resonators designed so as to maximize the spectral and spatial encoding capacities. The proposed RFID tag operates an over 4 GHz frequency band (i.e., 6.5 GHz to 10.5 GHz). The tag is simulated, fabricated, and tested in a nonanechoic milieu. The measured data have shown good agreement with the simulation results, with respect to resonators’ frequency positions, null depth, and null bandwidth over the operating spectrum. The proposed design achieves spectral and spatial encoding capacities of 4.5 bits/GHz and 18.8 bits/cm2, respectively. This, in turn, gives an encoding density of 4.7 bits/GHz/cm2. For code identification, we exploit the frequency content of the backscattered signals and identify similarity/correlation features with reference codes.

Design and Analysis of Multi-Resonators Loaded Broadband Antipodal Tapered Slot Antenna for Chipless RFID Applications

Chipless radio frequency identification (RFID) technology recently observed a growing interest, mainly because of its wide area of applications, and huge potential market, with the advent of Internet of Things era. Recently, in the demonstration of high capacity chipless RFID tags, ultra-wide-band technology has been proposed. It can enable development of robust chipless RFID systems with the promising features of low cost, compact, and lightweight. In response, we propose a novel scheme of broadband chipless RFID tagging that is based on slot coupled tapered slot antenna (TSA) loaded with a set of resonators, referred to as multi-resonators filters (MRF). Using numerical simulations, out of 256 combinations, randomly selected 14 different 8-bit MRF circuits operating over the frequency band 4 to 9 GHz are designed and their spectral and time domain responses under short and open terminations are recorded. The time domain signatures, generated due to high impedance mismatches along the microstrip lines of MRFs terminated with open and short circuits, are quantified by finding the cross-correlation among the signals and that is done by calculating the pulse fidelity factor. The designed MRFs are integrated with TSA to develop chipless RFID tags, referred to as MRF-TSA tags. Our designed TSA operates over 3.5–18 GHz band with an average gain that exceeds 6.5 dBi. The retransmitted time domain signals from the MRF-TSA tags are modulated by loading the antenna with MRFs terminated with either short or open loads. The recorded time domain signals are reasonably distinguishable since 85% (96%) of fidelity factor values among the 14 different MRF-TSA tags with open/short termination are less than 0.70 (0.8), respectively. Finally, for verification purposes, two different MRF-TSA based chipless tags are designed and fabricated. RFID monostatic measurements based on the use of vector network analyzer are also reported.

Design of dual polarized hybrid LTCC antenna for UWB RFID applications

In this paper, we present the simulated design of a dual-polarized H-shaped aperture-coupled microstrip antenna for ultra-wideband radio frequency identification (UWB-RFID) applications. The antenna has a compact design (30 × 30 × 6.9 mm3) with a hybrid structure. The feed portion is on a Ferro A6M low-temperature co-fired ceramic (LTCC) substrate, while the square patches are deposited onto Rogers RT-5880 substrate layers. The antenna is designed to operate in the frequency range of 6–8 GHz. The proposed antenna achieves a dual-polarized broadside radiation pattern having a high gain of 7.71 dB. It also achieves a fractional bandwidth of 28.5% and a port isolation of more than −25 dB at the center frequency of 7 GHz.

UWB monopole antenna chipless RFID tags using 8-bit open circuit stub resonators

The design of a chipless ultra-wideband (UWB) radiofrequency identification (RFID) tag is presented in this paper. It consists of two microstrip-line-fed circular disc monopole antenna and eight-bit open circuit (OC) stub resonator. The proposed tag can be identified based on spectral signature (SS) that is used to encode the incident signals in the frequency range from 4 GHz to 8 GHz. The designed monopole antenna and OC stub resonators are characterized using full wave simulation programs. Complete RFID system is modeled and time domain characteristics of the pulse received at the receivers antenna is studied. Results show that the encoded pulse exhibits different signature compared to the incident pulse that can be easily distinguished in time domain.

Design of a Chipless UWB RFID Tag Using CPW Circular Monopole Antennas and Multi-Resonators

This paper presents the design of a chipless ultra-wideband radio frequency identification (UWB RFID) tag. The tag is composed of two modified coplanar waveguide (CPW) circular monopole antennas and seven bit multi-resonator. The proposed tag can be identified based on spectral signature (SS) that is used to encode the incident signals in the frequency range from 6 GHz to 8 GHz. The designed monopole antennas and multi- resonator are characterized using full wave simulation program. Complete RFID system is modeled and time domain characteristics of the pulse received at the receivers antenna is studied. Results show that the encoded pulse exhibits different signature compared to the incident pulse that can be easily distinguished in time domain.