Browsing by Author "Tsilipakos, Odysseas"

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Engraved Split-Ring Resonators as Potential Microwave Sensors for Olive Oil Quality Control
(2024-05-28) Viskadourakis, Zacharias; Theodosi, Anna; Katsara, Klytaimnistra; Sevastaki, Maria; Fanourakis, George; Tsilipakos, Odysseas; Papadakis, Vassilis M.; Kenanakis, George
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In this study, microwave complementary split-ring resonators are explored regarding their sensing capability against olive oil adulteration. In particular, millimeter-scale complementary split-ring resonators were developed employing the computer numerical control method, in combination with a home-built mechanical engraver. Their electromagnetic behavior was comprehensively studied, both experimentally and theoretically, in the frequency range of 2-9 GHz. Furthermore, their electromagnetic response was investigated in the presence of different types of edible oils, such as virgin olive oil, corn oil, and soybean oil. Both experimental results and theoretical simulations clearly reveal the distinct response of the fabricated complementary resonators to different oil types. Even more, they exhibit a significant response in oil mixtures, enabling the detection of possible adulteration in olive oil. Consequently, it becomes evident that mechanically engraved microwave complementary split-ring resonators can be efficiently realized as potential sensors for olive oil quality control.
Exploration of Intercell Wireless Millimeter-Wave Communication in the Landscape of Intelligent Metasurfaces
(2019) Tasolamprou, Anna C.; Pitilakis, Alexandros; Abadal, Sergi; Tsilipakos, Odysseas; Timoneda, Xavier; Taghvaee, H.; Mirmoosa, M. S.; Liu, Fu; Liaskos, Christos; Tsioliaridou, Ageliki; Ioannidis, Sotiris; Kantartzis, Nikolaos V.; Manessis, Dionysios; Georgiou, Julius; Cabellos-Aparicio, Albert; Alarcón, Eduard; Pitsillides, Andreas; Akyildiz, I. F.; Tretyakov, S. A.; Economou, E. N.; Kafesaki, Maria; Soukoulis., C. M.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Software-defined metasurfaces are electromagnetically ultra-thin, artificial components that can provide engineered and externally controllable functionalities. The control over these functionalities is enabled by the metasurface tunability, which is implemented by embedded electronic circuits that modify locally the surface resistance and reactance. Integrating controllers within the metasurface cells, able to intercommunicate and adaptively reconfigure it, thus imparting a desired electromagnetic operation, opens the path towards the creation of an artificially intelligent (AI) fabric where each unit cell can have its own sensing, programmable computing, and actuation facilities. In this work we take a crucial step towards bringing the AI metasurface technology to emerging applications, in particular exploring the wireless mm-wave intercell communication capabilities in a software-defined HyperSurface designed for operation in the microwave regime. We examine three different wireless communication channels within the landscape of the reflective metasurface: Firstly, in the layer where the control electronics of the HyperSurface lie, secondly inside a dedicated layer enclosed between two metallic plates, and, thirdly, inside the metasurface itself. For each case we examine the physical implementation of the mm-wave transceiver nodes, we quantify communication channel metrics, and we identify complexity vs. performance trade-offs.
Intelligent Metasurfaces with Continuously Tunable Local Surface Impedance for Multiple Reconfigurable Functions
(2019-04-09) Liu, Fu; Tsilipakos, Odysseas; Pitilakis, Alexandros; Tasolamprou, Anna C.; Mirmoosa, Mohammad Sajjad; Kantartzis, Nikolaos V.; Kwon, Do Hoon; Kafesaki, Maria; Soukoulis, Costas M.; Tretyakov, Sergei A.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Electromagnetic metasurfaces can be characterized as intelligent if they are able to perform multiple tunable functions, with the desired response being controlled by a computer influencing the individual electromagnetic properties of each metasurface inclusion. In this paper, we present an example of an intelligent metasurface that operates in the reflection mode in the microwave frequency range. We numerically show that, without changing the main body of the metasurface, we can achieve tunable perfect absorption and tunable anomalous reflection. The tunability features can be implemented using mixed-signal integrated circuits (ICs), which can independently vary both the resistance and reactance, offering complete local control over the complex surface impedance. The ICs are embedded in the unit cells by connecting two metal patches over a thin grounded substrate and the reflection property of the intelligent metasurface can be readily controlled by a computer. Our intelligent metasurface can have a significant influence on future space-time modulated metasurfaces and a multitude of applications, such as beam steering, energy harvesting, and communications.
Intercell Wireless Communication in Software-defined Metasurfaces
(2018-04-26) Tasolamprou, Anna C.; Mirmoosa, Mohammad Sajjad; Tsilipakos, Odysseas; Pitilakis, Alexandros; Liu, Fu; Abadal, Sergi; Cabellos-Aparicio, Albert; Alarcon, Eduard; Liaskos, Christos; Kantartzis, Nikolaos V.; Tretyakov, Sergei; Kafesaki, Maria; Economou, Eleftherios N.; Soukoulis, Costas M.
A4 Artikkeli konferenssijulkaisussa
Tunable metasurfaces are ultra-thin, artificial electromagnetic components that provide engineered and externally adjustable functionalities. The programmable metasurface, the HyperSurFace, concept consists in integrating controllers within the metasurface that interact locally and communicate globally to obtain a given electromagnetic behaviour. Here, we address the design constraints introduced by both functions accommodated by the programmable metasurface, i.e., the desired metasurface operation and the unit cells wireless communication enabling such programmable functionality. The design process for meeting both sets of specifications is thoroughly discussed. Two scenarios for wireless intercell communication are proposed. The first exploits the metasurface layer itself, while the second employs a dedicated communication layer beneath the metasurface backplane. Complexity and performance trade-offs are highlighted.
A Multi-Functional Reconfigurable Metasurface: Electromagnetic Design Accounting for Fabrication Aspects
(2021-03) Pitilakis, Alexandros; Tsilipakos, Odysseas; Liu, Fu; Kossifos, Kypros M.; Tasolamprou, Anna C.; Kwon, Do Hoon; Mirmoosa, Mohammad Sajjad; Manessis, Dionysios; Kantartzis, Nikolaos V.; Liaskos, Christos; Antoniades, Marco A.; Georgiou, Julius; Soukoulis, Costas M.; Kafesaki, Maria; Tretyakov, Sergei A.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
In this article, we present the theoretical considerations and the design evolution of a proof-of-concept reconfigurable metasurface, primarily used as a tunable microwave absorber, but also as a wavefront manipulation and polarization conversion device in reflection. We outline the design evolution and all considerations taken into account, from the selection of patch shape, unit cell size, and substrate to the topology of the structure that realizes the desired tunability. The presented design conforms to fabrication restrictions and is codesigned to work with an integrated circuit (IC) chip for providing tunable complex loads to the metasurface, using a commercially available semiconductor process. The proposed structure can perform multiple tunable functionalities by appropriately biasing the IC. Perfect absorption for a wide range of incidence angles of both linear polarization states, accommodating a spectral range in the vicinity of 5 GHz, with potential also for wavefront control, exemplified via anomalous reflection and polarization conversion. The end vision is for such a design to be scalable and deployable as a practical HyperSurface, i.e., an intelligent multifunctional metasurface capable of concurrent reconfigurable functionalities: absorption, beam steering, polarization conversion, wavefront shaping, holography, and sensing.
Toward Intelligent Metasurfaces: The Progress from Globally Tunable Metasurfaces to Software-Defined Metasurfaces with an Embedded Network of Controllers
(2020-09-01) Tsilipakos, Odysseas; Tasolamprou, Anna C.; Pitilakis, Alexandros; Liu, Fu; Wang, Xuchen; Mirmoosa, Mohammad Sajjad; Tzarouchis, Dimitrios C.; Abadal, Sergi; Taghvaee, Hamidreza; Liaskos, Christos; Tsioliaridou, Ageliki; Georgiou, Julius; Cabellos-Aparicio, Albert; Alarcón, Eduard; Ioannidis, Sotiris; Pitsillides, Andreas; Akyildiz, Ian F.; Kantartzis, Nikolaos V.; Economou, Eleftherios N.; Soukoulis, Costas M.; Kafesaki, Maria; Tretyakov, Sergei
A2 Katsausartikkeli tieteellisessä aikakauslehdessä
Metasurfaces, the ultrathin, 2D version of metamaterials, have recently attracted a surge of attention for their capability to manipulate electromagnetic waves. Recent advances in reconfigurable and programmable metasurfaces have greatly extended their scope and reach into practical applications. Such functional sheet materials can have enormous impact on imaging, communication, and sensing applications, serving as artificial skins that shape electromagnetic fields. Motivated by these opportunities, this progress report provides a review of the recent advances in tunable and reconfigurable metasurfaces, highlighting the current challenges and outlining directions for future research. To better trace the historical evolution of tunable metasurfaces, a classification into globally and locally tunable metasurfaces is first provided along with the different physical addressing mechanisms utilized. Subsequently, coding metasurfaces, a particular class of locally tunable metasurfaces in which each unit cell can acquire discrete response states, is surveyed, since it is naturally suited to programmatic control. Finally, a new research direction of software-defined metasurfaces is described, which attempts to push metasurfaces toward unprecedented levels of functionality by harnessing the opportunities offered by their software interface as well as their inter- and intranetwork connectivity and establish them in real-world applications.
Toward the Realization of a Programmable Metasurface Absorber Enabled by Custom Integrated Circuit Technology
(2020-01-01) Kossifos, Kypros M.; Petrou, Loukas; Varnava, Giorgos; Pitilakis, Alexandros; Tsilipakos, Odysseas; Liu, Fu; Karousios, Petros; Tasolamprou, Anna C.; Seckel, Manuel; Manessis, Dionysios; Kantartzis, Nikolaos V.; Kwon, Do Hoon; Antoniades, Marco A.; Georgiou, Julius
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The realization of a programmable metasurface, enabled by a custom application-specific integrated circuit (ASIC), is presented in this paper. The ASIC is used to provide an adaptive complex impedance load to each of the metasurface unit cells. Various technology nodes are analyzed for the implementation of tunable complex impedance loading elements before one is selected for the final implementation, in which four complex loads are placed within each integrated circuit, and each load is controlled by two digital-to-analog converters. Furthermore, the ASICs populate the back of the metasurface to form a mesh network to enable programmability. The paper includes practical limitations that affect the realization, as well as an example adaptive metasurface absorber that builds upon the practical tuning range of the ASIC. Perfect absorption for both transverse electric and transverse magnetic polarization is demonstrated.