Dual-Band Tunable Recursive Active Filter

This letter presents a novel recursive active filter topology that provides dual-band performance, with independent tuning capability in both bands. The dual-band operation is achieved by using two independent feedback lines. Additionally, linear phase shifters based on left-handed cells are included in these two branches in order to tune the center frequency of both pass bands

Flatland plasmonics and nanophotonics based on graphene and beyond

In this paper, we review and discuss how the recently discovered two-dimensional (2D) Dirac materials, particularly graphene, may be utilized as new efficient platforms for excitations of propagating and localized surface plasmon polaritons (SPPs) in the terahertz (THz) and mid-infrared (MIR) regions. The surface plasmon modes supported by the metallic 2D materials exhibit tunable plasmon resonances that are essential, yet missing, ingredients needed for THz and MIR photonic and optoelectronic devices. We describe how the atomically thin graphene monolayer and metamaterial structures based on it may tailor and control the spectral, spatial, and temporal properties of electromagnetic radiation. In the same frequency range, the newly unveiled nonlocal, nonlinear, and nonequilibrium electrodynamics in graphene show a variety of nonlinear and amplifying electromagnetic responses, whose potential applications are yet unexplored. With these 2D material platforms, virtually all plasmonic, optoelectronic, and nonlinear functions found in near-infrared (NIR) and visible devices can be analogously transferred to the long-wavelength regime, even with enhanced tunability and new functionalities. The spectral range from THz to MIR is particularly compelling because of the many spectral fingerprints of key chemical, gas, and biological agents, as well as a myriad of remote sensing, imaging, communication, and security applications

Antenna designs based on metamaterial-inspired structures

The research presented in this thesis concerns antenna designs based on metamaterial-inspired structures. Based on a review of the existing literature and understanding of the background theories, different metamaterial-inspired structures are applied to designs of resonant antennas (RAs) and leaky wave antennas (LWAs) for improved antenna characteristics. Extended composite right/left-handed (ECRLH) unit cell structures enable the RA designs with multiband or wideband properties; the novel metamaterial-inspired supercell structures enable the LWA designs with the dual-passband property and the backward-to-forward leaky-wave radiation characteristics in each passband. In addition, two tunable antennas are presented to mainly achieve the frequency reconfigurability and possibly the pattern reconfigurability by electronically controlling surface-mounted semiconductor varactors or discrete ferroelectric barium strontium titanium (BST) thin-film varactors. Furthermore, the uncertainty analysis in determination of permittivity of BST film materials from the characterization process is discussed in this thesis, in order to provide the design clues when the antenna with BST materials is designed. The conclusions are drawn and the possible future research directions are explained as well

Overcoming traditional electrically small antenna tradeoffs with meta-structures

© 2017 Euraap. Metamaterial-inspired near-field resonant parasitic (NFRP) electrically small antennas (ESAs) have been designed and experimentally validated to have not only high radiation efficiencies, but also multi-functionality, large bandwidths, high directivities and reconfigurability. These expanded capabilities have been attained by introducing more complex meta-structures, i.e., multiple NFRP elements loaded with fixed and tunable lumped elements, as well as active circuits. Different classes of passive and active NFRP ESAs that have successfully produced these effects will be reviewed, and several recently reported ESA systems will be introduced and discussed

Passive Planar Microwave Devices

The aim of this book is to highlight some recent advances in microwave planar devices. The development of planar technologies still generates great interest because of their many applications in fields as diverse as wireless communications, medical instrumentation, remote sensing, etc. In this book, particular interest has been focused on an electronically controllable phase shifter, wireless sensing, a multiband textile antenna, a MIMO antenna in microstrip technology, a miniaturized spoof plasmonic antipodal Vivaldi antenna, a dual-band balanced bandpass filter, glide-symmetric structures, a transparent multiband antenna for vehicle communications, a multilayer bandpass filter with high selectivity, microwave planar cutoff probes, and a wideband transition from microstrip to ridge empty substrate integrated waveguide

A Miniaturized Printed Circuit CRLH Antenna-based Hilbert Metamaterial Array

With the development of communication systems and antennas, various challenges arise that require antennas of small size with enhanced performance. Metamaterials (MTM) defects introduced a considerable solution to such a challenge. Therefore, in this paper, a lightweight with low profile antenna is designed based on a novel design of a Composite Right/Left-Handed CRLH-MTM Hilbert array. The proposed CRLH-MTM unit cell consists of a T-symmetric CRLH unit cell conjugated to the 3rd-order Hilbert on the ground plane through a T-stub structure to enhance the gain-bandwidth product. CST-MWS is used to stimulate and design the proposed antenna structure. The antenna parameters are optimized to evaluate the antenna performance in gain and S11. As a result, the antenna can operate forward and backwards with a large scanning angle ranging from +34o to -134o with changing frequency, and dual-band extended from 3.3GHz to 4.2GHz 4.86GHz 5.98GHz with a maximum gain of 7.24dBi and 3.74dBi, respectively. The beam steering is achieved by trough controlling the switching operation of PIN diodes. As a result, the antenna can scan up to 8° from 34° to 42° at 3.5GHz with constant gain along with the operating range

Multiple Slot Fractal Structured Antenna for Wi-Fi and Radio Altimeter for uncertain Applications

A multiple slot fractal antenna design has been determined communication efficiency and its multi-function activities.  High-speed small communication devices have been required for future smart chip applications, so that researchers have been employed new and creative antenna design. Antennas are key part in communication systems, those are used to improve communication parameters like gain, efficiency, and bandwidth. Consistently, modern antennas design with high bandwidth and gain balancing is very difficult, therefore an adaptive antenna array chip design is required. In this research work a coaxial fed antenna with fractal geometry design has been implemented for Wi-Fi and Radio altimeter application. The fractal geometry has been taken with multiple numbers of slots in the radiating structure for uncertain applications. The coaxial feeding location has been selected based on the good impedance matching condition (50 Ohms). The overall dimension mentioned for antenna are approximately 50X50X1.6 mm on FR4 substrate and performance characteristic analysis is performed with change in substrate material presented in this work. Dual-band resonant frequency is being emitted by the antenna with resonance at 3.1 and 4.3 GHz for FR4 substrate material and change in the resonant bands is obtained with change in substrate. The proposed Antenna is prototyped on Anritsu VNA tool and presented the comparative analysis like VSWR 12%, reflection coefficient 9.4%,3D-Gain 6.2% and surface current 9.3% had been improved