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Author

Roberto Vallauri

Bio: Roberto Vallauri is an academic researcher from Telecom Italia. The author has contributed to research in topics: Antenna (radio) & Radiation pattern. The author has an hindex of 5, co-authored 10 publications receiving 63 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors presented a novel switched beam antenna (SBA) consisting of four identical metamaterial-inspired electrically short printed monopoles, vertically placed at the corners of a grounded square board.
Abstract: We present a novel switched beam antenna (SBA) consisting of four identical metamaterial-inspired electrically short printed monopoles, vertically placed at the corners of a grounded square board. The antenna is designed to operate in the frequency range 1600-2700 MHz, with global dimensions 120 mm × 120 mm × 30 mm. The SBA has been first numerically simulated and optimized and, then, fabricated and tested. Numerical and experimental results show a good agreement. The obtained switched beam capabilities, the achieved realized gain levels, and the synthesized radiation pattern shapes on the horizontal plane, make the proposed SBA a good candidate as a radiating element of a receiving module for wireless telecommunication systems (DCS, UMTS, Wi-Fi, LTE) in areas with reduced signal coverage and/or high interference levels.

20 citations

Journal ArticleDOI
TL;DR: In this paper, the definitions of EMF zones and the zone's boundaries around an antenna are revised and tailored for the evaluation of human exposure to the EMFs, and the space around the antenna is sectioned into three regions: reactive, radiating near field, and far field.
Abstract: The regulatory framework on human exposure to electromagnetic fields (EMFs) is a crucial task that the telecommunication operators and the authorities have to face. Some procedures have been introduced in standards, based on both computations and measurements, for the assessment of the compliance of the radio transmitters to the given EMF limits. The procedures could vary depending on the position of the observation point around the transmitting antennas. In this article, the definitions of EMF zones and the zone's boundaries around an antenna are revised and tailored for the evaluation of human exposure to the EMFs. The space around the antenna is sectioned into three regions: reactive, radiating near field, and far field. The analytical and numerical results are used to support the proposed region's boundaries. Some examples of region boundaries are given for a few antenna types.

18 citations

Journal ArticleDOI
TL;DR: In this paper, a simplified and conservative method for the assessment of the electromagnetic exposure in proximity of a radiator is proposed, which uses the Fraunhofer antenna pattern to estimate the electromagnetic field radiated in the Fresnel region of base transceiver station (BTS) antennas.
Abstract: The letter focuses on a simplified and conservative method for the assessment of the electromagnetic exposure in proximity of a radiator. The method allows the use of the Fraunhofer antenna pattern to estimate the electromagnetic field radiated in the Fresnel region of base transceiver station (BTS) antennas. The proposed approach is introduced from a theoretical point of view and validated with simulations and measurements on linear and planar array systems. For its application, a specific description of the boundaries of the Fresnel region for a generic antenna of parallelepipedal shape, which takes into account the dependency from the direction of observation, is introduced. The method provides a rapid and simple solution of assessment issues in relation to the electromagnetic fields exposure limits.

11 citations

Proceedings Article
23 Mar 2009
TL;DR: In this article, a numerical simplified method is proposed for an easy-to-apply assessment of human exposure in the Fresnel region of an antenna. But the method is limited to linear arrays, since this antenna typology represents the most common radiator used for the construction of Base Transmitting Stations (BTS).
Abstract: The paper analyses the implementation of a numerical simplified method, for an easy-to-apply assessment of human exposure in the Fresnel region of an antenna. The method allows the evaluation of the electromagnetic field, starting exclusively from the knowledge of far field radiation patterns. In the framework of this paper, the analysis is limited to linear arrays, since this antenna typology represents the most common radiator used for the construction of Base Transmitting Stations (BTS). The obtained results illustrate the reliability of the method and confirm that it is rather conservative, without introducing excessive overestimates.

6 citations

Patent
23 May 2002
TL;DR: In this paper, the authors evaluate electrical field levels in the near-zone of transmitting antennas, particularly linear array antenna widely used in cellular telephony systems, providing accurate evaluation while requiring reduced processing times and a restricted set of input data, such as physical external dimensions of the antenna.
Abstract: The method for evaluating electrical field levels in the near-zone of transmitting antennas, particularly linear array antenna widely used in cellular telephony systems, provides accurate evaluation while requiring reduced processing times and a restricted set of input data, such as physical external dimensions of the antenna, its gain and its radiation patterns in the vertical plane and in the horizontal plane.

5 citations


Cited by
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Journal ArticleDOI
18 May 2015
TL;DR: This paper is aimed at reviewing the latest advances on reconfigurable metamaterial engineering from the methodological perspective also providing a comprehensive and balanced survey on latest concepts, current trends, and envisaged future developments on this active field of research.
Abstract: The introduction of electromagnetic (EM) media with unique field manipulation properties, collectively labelled as metamaterials, has boosted the interest toward the design, the fabrication, and the testing of artificial materials whose features can be engineered according to the applicative requirements and user objectives. In this framework, the long-term promise of reconfigurable metamaterial theory (i.e., the possibility to change the EM response of a 2-D/3-D material arbitrarily and in real time) has given the designers an extremely wide number of new degrees of freedom for the synthesis of innovative adaptive systems. Moreover, successful experimental validations of reconfigurable metamaterials in the entire EM spectrum from microwaves to optical frequencies have further stimulated academic and industrial interests in developing devices with enhanced performances, efficiency, and robustness. Nevertheless, the exploitation of reconfigurable metamaterials in commercial devices is still an open problem with several challenges from both the theoretical and technological viewpoints. This paper is then aimed at reviewing the latest advances on reconfigurable metamaterial engineering from the methodological perspective also providing a comprehensive and balanced survey on latest concepts, current trends, and envisaged future developments on this active field of research.

152 citations

Book ChapterDOI
TL;DR: This chapter provides a unified treatment of these bands with particular emphasis on their propagation characteristics, channel models, design and implementation considerations, and potential applications to 6G wireless.
Abstract: With the standardization of 5G, commercial millimeter wave (mmWave) communications has become a reality despite all the concerns about the unfavorable propagation characteristics of these frequencies. Even though the 5G systems are still being rolled out, it is argued that their gigabits per second rates may fall short in supporting many emerging applications, such as 3D gaming and extended reality. Such applications will require several hundreds of gigabits per second to several terabits per second data rates with low latency and high reliability, which are expected to be the design goals of the next generation 6G communications systems. Given the potential of terahertz (THz) communications systems to provide such data rates over short distances, they are widely regarded to be the next frontier for the wireless communications research. The primary goal of this chapter is to equip readers with sufficient background about the mmWave and THz bands so that they are able to both appreciate the necessity of using these bands for commercial communications in the current wireless landscape and to reason the key design considerations for the communications systems operating in these bands. Towards this goal, this chapter provides a unified treatment of these bands with particular emphasis on their propagation characteristics, channel models, design and implementation considerations, and potential applications to 6G wireless. A brief summary of the current standardization activities related to the use of these bands for commercial communications applications is also provided.

65 citations

Journal ArticleDOI
TL;DR: In this article, a coplanar waveguide (CPW)-fed dual-band antenna operating at linear and circular polarization is presented, where a right/left-handed unit cell is designed as a radiation element that can provide zerothmode resonance and positive-mode resonance at the lower and upper frequency.
Abstract: A coplanar waveguide (CPW)-fed dual-band antenna operating at linear and circular polarization is presented in this letter. A novel composite right/left-handed (CRLH) unit cell is designed as a radiation element that can provide zeroth-mode resonance and positive-mode resonance at the lower and upper frequency. A TM01 mode orthogonal to +1st-Order is excited by a square complementary split-ring resonator (S-CSRR) in order to form a circular polarization. The equivalent circuit model is applied to analyze and design the CRLH unit cell. The antenna has a linearly polarized slot-like radiation characteristic at the lower frequency and a circularly polarized patch-like radiation characteristic at the upper frequency. Also, the total electrical size of the fabricated dual-band antenna employing a single unit cell was 0.14λ0 ×0.16λ0 ×0.01λ0 at the lower frequency. Simulation and experimental results are used to verify the theoretical prediction .

63 citations

Proceedings Article
14 Mar 2018
TL;DR: The three dimensional spatial channel model standardized by the Third Generation Partnership Project is proposed in order to assess reasonably foreseeable compliance boundaries of massive MIMO BSs and shows that the statistical approach developed in this paper allows reducing to nearly half the compliance distance when compared to the traditional method.
Abstract: Massive multiple-input multiple-output (MIMO) is a fundamental enabler to provide high data throughput in next generation cellular networks. By equipping the base stations (BSs) with tens or hundreds of antenna elements, narrow and high gain beams can be used to spatially multiplex several user equipment (UE) devices. While increasing the achievable performance, focusing the transmit power into specific UE directions also poses new issues when performing the radio frequency (RF) exposure assessment. In fact, the spatial distribution of the actual BS transmit power strongly depends on the deployment scenario and on the position of the UEs. Traditional methods for assessing the RF exposure compliance boundaries around BS sites are generally based on maximum transmit power and static beams. In massive MIMO systems, these approaches tend to be very conservative, in particular when time averaging is properly considered. In this work, we propose to leverage the three dimensional spatial channel model standardized by the Third Generation Partnership Project in order to assess reasonably foreseeable compliance boundaries of massive MIMO BSs. The analysis is performed by considering BSs fully loaded and different configurations of active UEs per cell. Numerical results show that the statistical approach developed in this paper allows reducing to nearly half the compliance distance when compared to the traditional method.

47 citations

Journal ArticleDOI
TL;DR: The ability to shrink the physical dimensions of an antenna without significant performance degradation has been of great interest for over half a century as mentioned in this paper, and several antenna miniatu cation techniques have been proposed.
Abstract: The ability to shrink the physical dimensions of an antenna without significant performance degradation has been of great interest for over half a century. Over the decades, several antenna miniatu...

37 citations