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Dr. Joao Ricardo Reis
Polytechnic of Leiria
+1
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Representative Publications
View All Publications21 June 2019 in IEEE Access
Journal Article
JRJoao Ricardo Reis
Joao Ricardo ReisMVMario Vala
Mario Vala
Rafael F. S. CaldeirinhaThis article presents a thorough review on transmitarray devices particularly aiming antenna beamsteering, gathering some of the most relevant solutions published by the scientific community in the field. Firstly, the background for realising one-and two-dimensional antenna beamsteering with a transmitarray is introduced. Subsequently, several examples of unit-cells for transmitarray implementation and complete transmitarray designs presented in the literature are outlined. Each solution is analyzed in detail, identifying the nature of its layout, e.g. based on microstrip patchs, frequency selective surfaces (FSS) or metamaterials (MM), and the method employed to enable electronic reconfigurability, e.g. p-i-n diodes, varactor diodes or Microelectromechanical systems (MEMS). In addition, some models with the capability of controlling the wavefront polarization modes are also included herein since these are the base of hybrid transmitarrays, i.e. transmitarray with both electronic beamsteering and polarization control. Finally, all the models are compared against each other in order to highlight their benefits and limitations, summarizing their main characteristics such as frequency of operation and bandwidth, insertion loss, physical dimensions and maximum beamsteering range, when available.
4 July 2017 in IEEE Transactions on Antennas and Propagation
Journal Article
JRJoao Ricardo Reis
Joao Ricardo ReisRafael F. S. CaldeirinhaAHAkram Hammoudeh
Akram Hammoudeh
NCNigel Copner
Nigel CopnerA novel electronically reconfigurable transmitarray (TA) with 2-D beamsteering capability is presented in this communication. The proposed structure, inspired on frequency selective surfaces loaded with varactor diodes, allows the phase range of each TA element to be individually controlled enabling an automated steering of the main lobe of an original antenna pattern, in both elevation and azimuth planes (2-D beamsteering). This has been demonstrated on a 5 × 5 unit-cell stacked structure with active feeding, coupled to the aperture of a standard gain horn antenna. A complete electromagnetic study using CST Microwave Studio is presented to evaluate and characterize the TA elements and the effect the proposed feeding network has on the structure's behavior. Following initial simulations, a prototype of the active TA has been characterized. Automated antenna beamsteering with ranges up to Az = 28° and El = 26° and 1° of angular resolution, is achieved by means of electromagnetic simulations and validated against experimental results at 5.2 GHz.
18 March 2016 in IEEE Transactions on Antennas and Propagation
Journal Article
JRJoao Ricardo Reis
Joao Ricardo ReisNCNigel Copner
Nigel CopnerAHAkram Hammoudeh
Akram Hammoudeh
ZAZaid Muhi-Eldeen Al-Daher
Zaid Muhi-Eldeen Al-Daher
Rafael F. S. CaldeirinhaRGRodolfo Gomes
Rodolfo Gomes +1
A novel two-dimensional (2-D) beamsteering transmitarray inspired on frequency selective surfaces is proposed in this paper. Individual phase range is applied to each transmitarray element and thus enabling the steering of the main lobe of an original antenna pattern in both elevation and azimuth planes (2-D-beamsteering). This has been demonstrated on a 5 × 5 unit-cell stacked structure, loaded with surface mount capacitors, coupled to the aperture of a standard gain horn antenna. Additionally, a complete parametric study based on electromagnetic (EM) simulations using CST Microwave Studio is presented to evaluate and characterize unit-cell parameters and the behavior of the array with various numbers of stacked layers and separation distances. Antenna beamsteering with ranges up to Az = 25° and El = 25° are achieved by means of EM simulations and validated against experimental results performed on a physical prototype at 5.3 GHz. The comparisons yield positive results and clearly demonstrate the potential and limitations of using such structures for beamsteering purposes.
15 January 2024 in IEEE Access
Journal Article
SCSaúl S. Carvalho
Saúl S. CarvalhoJRJoao Ricardo Reis
Joao Ricardo ReisAMArtur Mateus
Artur Mateus
Rafael F. S. CaldeirinhaThis comprehensive review explores advancements in the design, fabrication and performance evaluation of three-dimensional (3D) printed antennas, across different frequency ranges. The review highlights the use of diverse printing methods, materials and structures, to achieve specific antenna characteristics and designs, such as wide bandwidth, high gain, circular polarization, and beamforming capabilities. Simulation and measurement results are compared to assess antenna performance, considering parameters such as impedance bandwidth, radiation patterns, gain, and efficiency. The findings showcase the significant potential of 3D printing in the development of antennas for wireless communications, terahertz fr equencies, transmitarray, and multi-beam systems. Various printing techniques are employed to fabricate antennas with complex geometries and optimized performance. Rigorous measurements validate simulation results, addressing challenges related to printing resolution and material selection. This review emphasizes the contributions of 3D printing in antenna engineering, offering customization capabilities, rapid 3D, and improved performance.
1 July 2018 in IET Signal Processing
Journal Article
RGRodolfo Gomes
Rodolfo GomesJRJoao Ricardo Reis
Joao Ricardo ReisZAZaid Al‐Daher
Zaid Al‐DaherAHAkram Hammoudeh
Akram Hammoudeh
Rafael F. S. CaldeirinhaThis study presents a frequency spreading filter bank multi‐carrier (FS‐FBMC) waveform as a potential candidate for the fifth generation (5G) network applications at millimetre‐waves (mmWaves). The proposed model is developed based on the orthogonal frequency division multiplexing (OFDM) waveform standardised by IEEE 802.15.3c for 60 GHz high data‐rate applications. The effects of non‐linearities of power amplifiers (PAs) at 60 GHz for both OFDM and FS‐FBMC are presented and compared using a realistic PA model. In particular, the sensitivity of both transmission schemes to the non‐linear effects is investigated and its impact on the performance degradation in terms of output‐power‐backoff, is characterised over typical indoor line‐of‐sight, kiosk and residential, 60 GHz IEEE channel models. The assessment metrics considered are bit error rate and out‐of‐band emissions. This study concludes radio access schemes for future communication generations, i.e. 5G may employ OFDM for up‐link and FS‐FBMC for down‐link due to the sensitivity to PA non‐linearities of both waveforms.
29 April 2024 in IEEE Access
Journal Article
SCSaúl S. Carvalho
Saúl S. CarvalhoJRJoao Ricardo Reis
Joao Ricardo ReisRafael F. S. CaldeirinhaThis article offers a thorough review of the current state-of-the-art in four-dimensional (4D) printed antennas and possible adaptable designs. It provides a succinct examination of various categories of materials used in three-dimensional (3D) and 4D printing, including the utilization of smart materials available in both printable and synthesized forms. The review encompasses a concise analysis of fabrication techniques, stimuli, and response behaviors applied in various types of smart materials. These materials have the potential to fabricate antennas with tunable and reconfigurable properties, including frequency of operation, bandwidth, gain, and radiation pattern. Given the novelty of applying 4D printing in antenna technologies, the review also considers additional reconfigurable antennas with mechanically tunable properties, as well as those in non-printed formats. This exploration hints at potential adaptations to the latter for the development of 4D printed antennas. The utilization of 4D printing presents a complex yet intriguing approach to antenna fabrication, offering the possibility of creating dynamic antennas with sophisticated characteristics.
About Me
Joao Reis was born in Lisbon, Portugal, in 1987. He received the undergraduate degree in Electrical Engineering, Electronics & Telecommunications, from the Polytechnic Institute of Leiria (IPL), Portugal, in 2010. Between 2010 and 2013 he attended the Master's degree in same technical field, and in the same institution. In 2018, he was awarded a Ph.D in Electrical Engineering, specialization in antennas and propagation, by the University of South Wales, Treforest, United Kingdom, for his research work on the topic: "Novel antenna beamsteering for wireless applications". Currently, he is a researcher at Instituto de Telecomunicações, Portugal, group of Antennas & Propagation Leiria (A&P-Lr), being involved in several international projects, namely WSN-EN, FLY.PT, PAC-Portugal Autocluster for the future and Invisible5G. J. Reis is also an invited lecturer at ESTG-IPL, lecturing and (co-) supervising several undergraduate final year projects and master dissertations. He is currently a reviewer for several top international journals in the field of antennas and propagation, namely IEEE TAP, IET MAP and Wiley IJCS. His current research interests include antennas and radio wave propagation, beamsteering systems, RADAR, frequency selective surfaces and metamaterials. J. Reis has contributed to the literature with 2 patents submissions, 8 papers publications in highly reputed international journals and several international peer-reviewed conference publications.