In multi-user beamforming systems, the inter-user interference are controlled by spatial filtering. Since the implementation of digital beamforming is difficult due to high hardware cost of large array system, the analog beamforming system with one phase shifter at each antenna element is considered with antenna selection scheme. However, the beamwidth is not sufficiently narrow to perfectly re...

We discuss sparse phased array antenna architectures by the use of multiple transmit antenna positions in order to reduce the number of needed receiver channels. We also present a compact array architecture where the synthetic array antenna size is doubled without increasing the physical array size significantly. We compare sparse arrays of 10, 20, 40 and 80 receiver positions respectively (tog...

This paper presents brief account on smart antenna (SA) system. Smart or adaptive antenna arrays consist of an array of antenna elements with signal processing capability that optimizes the radiation and reception of a desired signal dynamically. SAs can place nulls in the direction of interferers via adaptive updating of weights linked to each antenna element. SAs thus cancel out most of the c...

Thinning of large antenna arrays in order to obtain low sidelobes is a difficult and nontrivial problem. Evolutionary programming (EP), a multi-agent stochastic search method, is proposed for optimizing thinned phased arrays with a large number of elements. Experiments are conducted to determine the efficiency of EP procedure in terms of the reliability in producing acceptable solutions and the...

By virtue of their ability to resonate at a wavelength much larger than the maximum dimension, Split-Ring Resonator (SRR) cells can be densely stacked to create energy harvesting arrays having per-unit-area power efficiency higher than a single SRR cell. While the concept of using metamaterial particles for electromagnetic energy harvesting had been demonstrated in our earlier work, the overall...

We report an approach for growing aligned ZnO nanowire arrays with a high degree control over size, orientation, dimensionality, uniformity, and possibly shape. Our method combines e-beam lithography and a low temperature hydrothermal method to achieve patterned and aligned growth of ZnO NWs at <100degreesC on general inorganic substrates, such as Si and GaN, without using catalyst. This approa...

Densely-packed, all-digital aperture arrays form a key area of technology development required for the Square Kilometre Array (SKA) radio telescope. The design of real-time signal processing systems for digital aperture arrays is currently a central challenge in pathfinder projects worldwide. We describe an hierarchical, frequency-domain beamforming architecture for synthesising a sky beam from...

The feasibility of a space-time decision feedback equalizer applied to the uplink of a 12.8 Mbit/s QPSK-system is demonstrated by means of link and system level simulations of real-world-like propagation and cell scenarios. Even for small antenna arrays of only 4 sensors an SDMA gain of 67% is achieved, i.e. 5 users per cell may be loaded to only 3 carrier frequencies. For scenarios with omnidi...

Title of Dissertation: CROSS-LAYER RESOURCE ALLOCATION ALGORITHMS IN WIRELESS NETWORKS WITH ANTENNA ARRAYS Tianmin Ren, Doctor of Philosophy, 2005 Dissertation directed by: Professor Leandros Tassiulas Department of Electrical and Computer Engineering The application of antenna array is a promising approach to improving the capacity of a wireless network. In this dissertation, we study the appl...

The presentation will give an overview of ONERA recent research work in the field of wideband printed antenna arrays. A special focus will be given to the comprehensive analysis and design optimization of multilayered printed arrays for wide bandwidth and wide scan angle operation.