1,885 research outputs found
Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review
Advances in reflectarrays and array lenses with electronic beam-forming
capabilities are enabling a host of new possibilities for these
high-performance, low-cost antenna architectures. This paper reviews enabling
technologies and topologies of reconfigurable reflectarray and array lens
designs, and surveys a range of experimental implementations and achievements
that have been made in this area in recent years. The paper describes the
fundamental design approaches employed in realizing reconfigurable designs, and
explores advanced capabilities of these nascent architectures, such as
multi-band operation, polarization manipulation, frequency agility, and
amplification. Finally, the paper concludes by discussing future challenges and
possibilities for these antennas.Comment: 16 pages, 12 figure
Fault Tolerance in Programmable Metasurfaces: The Beam Steering Case
Metasurfaces, the two-dimensional counterpart of metamaterials, have caught
great attention thanks to their powerful control over electromagnetic waves.
Recent times have seen the emergence of a variety of metasurfaces exhibiting
not only countless functionalities, but also a reconfigurable or even
programmable response. Reconfigurability, however, entails the integration of
tuning and control circuits within the metasurface structure and, as this new
paradigm moves forward, new reliability challenges may arise. This paper
examines, for the first time, the reliability problem in programmable
metamaterials by proposing an error model and a general methodology for error
analysis. To derive the error model, the causes and potential impact of faults
are identified and discussed qualitatively. The methodology is presented and
instantiated for beam steering, which constitutes a relevant example for
programmable metasurfaces. Results show that performance degradation depends on
the type of error and its spatial distribution and that, in beam steering,
error rates over 10% can still be considered acceptable
MEMS-reconfigurable metamaterials and antenna applications
This paper reviews some of our contributions to reconfigurable metamaterials,
where dynamic control is enabled by micro-electro-mechanical systems (MEMS)
technology. First, we show reconfigurable composite right/left handed
transmission lines (CRLH-TLs) having state of the art phase velocity variation
and loss, thereby enabling efficient reconfigurable phase shifters and
leaky-wave antennas (LWA). Second, we present very low loss metasurface designs
with reconfigurable reflection properties, applicable in reflectarrays and
partially reflective surface (PRS) antennas. All the presented devices have
been fabricated and experimentally validated. They operate in X- and Ku-bands.Comment: 8 pages; 8 figures; International Journal of Antennas and Propagatio
Photonic RF and microwave reconfigurable filters and true time delays based on an integrated optical Kerr frequency comb source
We demonstrate advanced transversal radio frequency (RF) and microwave
functions based on a Kerr optical comb source generated by an integrated
micro-ring resonator. We achieve extremely high performance for an optical true
time delay aimed at tunable phased array antenna applications, as well as
reconfigurable microwave photonic filters. Our results agree well with theory.
We show that our true time delay would yield a phased array antenna with
features that include high angular resolution and a wide range of beam steering
angles, while the microwave photonic filters feature high Q factors, wideband
tunability, and highly reconfigurable filtering shapes. These results show that
our approach is a competitive solution to implementing reconfigurable, high
performance and potentially low cost RF and microwaveComment: 15 pages, 11 Figures, 60 Reference
Application of adaptive antenna techniques to future commercial satellite communication
The purpose of this contract was to identify the application of adaptive antenna technique in future operational commercial satellite communication systems and to quantify potential benefits. The contract consisted of two major subtasks. Task 1, Assessment of Future Commercial Satellite System Requirements, was generally referred to as the Adaptive section. Task 2 dealt with Pointing Error Compensation Study for a Multiple Scanning/Fixed Spot Beam Reflector Antenna System and was referred to as the reconfigurable system. Each of these tasks was further sub-divided into smaller subtasks. It should also be noted that the reconfigurable system is usually defined as an open-loop system while the adaptive system is a closed-loop system. The differences between the open- and closed-loop systems were defined. Both the adaptive and reconfigurable systems were explained and the potential applications of such systems were presented in the context of commercial communication satellite systems
Full-Duplex Systems Using Multi-Reconfigurable Antennas
Full-duplex systems are expected to achieve 100% rate improvement over
half-duplex systems if the self-interference signal can be significantly
mitigated. In this paper, we propose the first full-duplex system utilizing
Multi-Reconfigurable Antenna (MRA) with ?90% rate improvement compared to
half-duplex systems. MRA is a dynamically reconfigurable antenna structure,
that is capable of changing its properties according to certain input
configurations. A comprehensive experimental analysis is conducted to
characterize the system performance in typical indoor environments. The
experiments are performed using a fabricated MRA that has 4096 configurable
radiation patterns. The achieved MRA-based passive self-interference
suppression is investigated, with detailed analysis for the MRA training
overhead. In addition, a heuristic-based approach is proposed to reduce the MRA
training overhead. The results show that at 1% training overhead, a total of
95dB self-interference cancellation is achieved in typical indoor environments.
The 95dB self-interference cancellation is experimentally shown to be
sufficient for 90% full-duplex rate improvement compared to half-duplex
systems.Comment: Submitted to IEEE Transactions on Wireless Communication
A Continuous Beam Steering Slotted Waveguide Antenna Using Rotating Dielectric Slabs
The design, simulation and measurement of a beam steerable slotted waveguide
antenna operating in X band are presented. The proposed beam steerable antenna
consists of a standard rectangular waveguide (RWG) section with longitudinal
slots in the broad wall. The beam steering in this configuration is achieved by
rotating two dielectric slabs inside the waveguide and consequently changing
the phase of the slots excitations. In order to confirm the usefulness of this
concept, a non-resonant 20-slot waveguide array antenna with an element spacing
of d = 0.58{\lambda}0 has been designed, built and measured. A 14 deg beam
scanning from near broadside ({\theta} = 4 deg) toward end-fire ({\theta} = 18
deg) direction is observed. The gain varies from 18.33 dB to 19.11 dB which
corresponds to the radiation efficiencies between 95% and 79%. The side-lobe
level is -14 dB at the design frequency of 9.35 GHz. The simulated co-polarized
realized gain closely matches the fabricated prototype patterns
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