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

Frequency, Radiation Pattern and Polarization Reconfigurable Antenna Using a Parasitic Pixel Layer

This communication presents a reconfigurable antenna capable of independently reconfiguring the operating frequency, radiation pattern and polarization. A switched grid of small metallic patches, known as pixel surface, is used as a parasitic layer to provide reconfiguration capabilities to existing antennas acting as driven element. The parasitic pixel layer presents advantages such as low profile, integrability and cost-effective fabrication. A fully operational prototype has been designed, fabricated and its compound reconfiguration capabilities have been characterized. The prototype combines a patch antenna and a parasitic pixel surface consisting of 6 x 6 pixels, with an overall size of 0.6 lambda x 0.6 lambda and 60 PIN-diode switches. The antenna simultaneously tunes its operation frequency over a 25% frequency range, steers the radiation beam over +/- 30 degrees in E and H-planes, and switches between four different polarizations ((x) over cap, (y) over cap, LHCP, RHCP). The average antenna gain among the different parameter combinations is 4 dB, reaching 6-7 dB for the most advantageous combinations. The distance between the driven and the parasitic layers determines the tradeoff between frequency tuning range (12% to 25%) and radiation efficiency (45% to 55%)

Miniature Multi-Element Antenna for Wireless Communications

Abstract-We present a novel broad-band miniature antenna and employ it in a multi-element geometry with diversity capabilities for wireless communications. This antenna (diameter 0.2 and thickness 0.06 ) consists of two stacked circular patches that create two cylindrical slots resonating at two slightly different frequencies, fed by a strategically positioned coaxial probe. An extensive parametric study and results for a prototype working at 5.2 GHz are presented. A multi-element geometry with two or four of such elements follows. Microelectromechanical system (MEMS)-based switches located within its geometry can not only change the working frequency of the design, but also activate a particular radiation beam depending on their specific location (resonant slot-aperture or feed line). Simulation results of a four-element antenna with dimensions 0 8 0 8 0 06 and a frequency band operation from 5 to 6 GHz are presented and compared to an experimental prototype. Circuit and radiation characteristics are discussed in terms of reconfigurability and diversity capabilities. Index Terms-Broad-band communications, diversity methods, mobile antennas

Miniature Multi-Element Antenna for Wireless Communications

Abstract-We present a novel broad-band miniature antenna and employ it in a multi-element geometry with diversity capabilities for wireless communications. This antenna (diameter 0.2 and thickness 0.06 ) consists of two stacked circular patches that create two cylindrical slots resonating at two slightly different frequencies, fed by a strategically positioned coaxial probe. An extensive parametric study and results for a prototype working at 5.2 GHz are presented. A multi-element geometry with two or four of such elements follows. Microelectromechanical system (MEMS)-based switches located within its geometry can not only change the working frequency of the design, but also activate a particular radiation beam depending on their specific location (resonant slot-aperture or feed line). Simulation results of a four-element antenna with dimensions 0 8 0 8 0 06 and a frequency band operation from 5 to 6 GHz are presented and compared to an experimental prototype. Circuit and radiation characteristics are discussed in terms of reconfigurability and diversity capabilities. Index Terms-Broad-band communications, diversity methods, mobile antennas

A Reconfigurable Spiral Antenna for Adaptive MIMO Systems

We present a reconfigurable spiral antenna for use in adaptive MIMO systems. The antenna is capable of changing the sense of polarization of the radiated field. It is fabricated by using an RF-MEMS technology compatible with microwave laminate substrates developed within the author’s group. The proposed antenna structure is built on a number of rectangular-shaped bent metallic strips interconnected to each other with RF-MEMS actuators. Two senses of polarization, RHCP and LHCP, are achieved by configuring the physical structure of the antenna, that is, by changing the winding sense of the spiral, through judicious activation of MEM actuators. The fabrication process for the monolithic integration of MEM actuators with bent microstrip pixels on RO4003-FR4 microwave laminate substrate is described. The measured and calculated radiation and impedance characteristics of the antenna are given. The operating frequency of the presented antenna design can easily be adjusted to be compatible with popular IEEE networking standards such as 802.11a