Phased array | EPFL Graph Search

In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. In a simple array antenna, the radio frequency current from the transmitter is fed to multiple individual antenna elements with the proper phase relationship so that the radio waves from the separate elements combine (superpose) to form beams, to increase power radiated in desired directions and suppress radiation in undesired directions. In a phased array, the power from the transmitter is fed to the radiating elements through devices called phase shifters, controlled by a computer system, which can alter the phase or signal delay electronically, thus steering the beam of radio waves to a different direction. Since the size of an antenna array must extend many wavelengths to achieve the high gain needed for narrow beamwidth, pha

A 24 GHz Phased-Array Doppler Radar Sensor and Transceiver Front-End for Smart Streetlights

Ban Wang

Recently, European Union advocates the smart Solid-State Lighting (SSL). The key factors are a smart-control scheme and an interaction with other networks, such as communication networks and traffic monitoring sensor networks. Public lighting represents a significant share of city total electricity costs, accounting for up to 60% of the budget. The adoption and deployment of new technologies, such as SSL that is based on Light-Emitting Diodes (LED), offer great opportunities to improve efficiencies and reduce costs. When combined with smart light management systems, SSL can save up the electricity used for lighting and significantly reduce energy and maintenance costs compared to current lighting installations. Moreover, streetlights are the infrastructures erecting beside or in the middle of the streets, so they seem to be the ideal observers of the traffic situations. Even though, other functional sensors, e.g., for measuring temperatures, CO2 and even particulate matter 2.5 (PM2.5), could be integrated in the smart-streetlights. Nowadays there are no sensors embedded in commercial available streetlights, except for the infrared motion sensor used only for pedestrian detection since their range is limited to about 10 meters, as well as there are limited networking capabilities, both in data-rate and functionalities, e.g. it is possible the dimming of only the entire file of streetlights. Hence, the idea to develop aWireless Sensor Front-End (WSFE), which is capable of working as motion sensor, namely a Doppler radar sensor, to monitor the road traffic as well as transceiver to communicate with the other network nodes. Such kind of WSFE could enable many streetlights futures, for example the lighting can be adapted to the traffic conditions and the presence of pedestrians on the sideways. Meanwhile, the communication function can build up a wireless network that can be used to manage the streetlight infrastructure and to collect information on traffic conditions, sensor reading, network status and so on. This thesis proposes a 24GHz 4-channel Phased-Array (Ph-A) front-end for smart-streetlight applications. The design exploits a 90nm Complementary Metal-Oxide-Semiconductor (CMOS) technology to benefit of the low-cost offered by CMOS technology. The architecture of the selected front-end allows the implementation of transceivers as well as Doppler radar sensors. Furthermore, the Ph-A technology is applied to the Doppler radar sensor in order to realizemulti-lane road scanning and pedestrian detection. The intercommunication between streetlights is based on a time-sharing mechanism and uses the same FE reconfigured as transceiver.[...]

EPFL2014

A portable picocell antenna for 5G

Danelys Rodríguez Avila

Deployable emergency communication systems are a backbone solution for replacing damaged network infrastructures and/or providing high-end services in case of an emergency event. It is important that such systems are up-to-date with the latest mobile network technology, for enabling connectivity to users and profiting from its enhanced capabilities. The advent of 5G promises higher data rates, lower latencies and improved quality of services when compared to previous generations. To achieve that, mm-Waves have been identified as a key element due to the wide available spectrum. The implementation of deployable emergency communication systems compatible with 5G mm-Waves technologies, thus benefiting from its prospective advantages, is of great interest. This thesis focuses on 5G mm-Waves antenna design for this kind of applications. The high network capacity demand, the unfavourable channel conditions at mm-Waves and the still underdeveloped related radio frequency (RF) technology define a group of challenging requirements on the antenna design. While directive antennas are required to mitigate the attenuation with distance at these bands, omnidirectional coverage still needs to be provided. In addition, wide bandwidth operation, high efficiency, and low cost and power consumption are desired. In this context, antennas with multibeam forming capabilities have been widely acknowledged as a key enabling technology to support 5G wireless communications, representing an attractive solution to provide omnidirectional coverage while supporting Multiple Input Multiple Output (MIMO) techniques. In this thesis, the design and implementation of a broadband efficient multibeam antenna for a portable picocell station are investigated. The picocell scenario in the context of emergency communications is studied and the antenna link budget is calculated considering mm-Waves propagation properties and available information on the upcoming standard. This leads to the definition of the design requirements and a preliminary antenna architecture that consists of an MxN antenna fed by a hybrid beamforming network (HBFN). This architecture is a promising approach for making multibeam antennas cost- and energy-efficient according to the latest research. The synthesis of the HBFN was realized considering the design constraints in elevation and azimuth such that the subarray, fed by an analog beamforming network, provides a csc2 pattern shape in elevation while M subarrays are controlled by a digital beamforming network to generate multiple orthogonal beams in azimuth. The antenna subarray was designed, fabricated and measured. Based on this, a study of the antenna array beamsteering capabilities in azimuth was carried out. After investigating the main parameters involved in improving its performance, the subarray design was optimized accordingly. The proposed antenna consists in a 12x6 array that works at 26 GHz with an impedance bandwidth higher than 12%. The radiation pattern shape in elevation is preserved over 7.3% of bandwidth. The antenna gain is superior to 10 dBi along the band of interest with a maximum value of 15 dBi. Simulated and measured results were compared, and the antenna beamsteering performance was tested for different sets of constraints indicating promising capabilities for a wide range of deployment scenarios. The proposed and validated design meets the requirements of the targeted applications on a practical low-profile implementation.

EPFL2021