SUBPROJECT 1: UPM-INTERSPACE

New Array Antenna Technologies and Digital Processing for the Future Integrated Terrestrial and Space-based Millimeter Wave Radio Systems

OBJECTIVES SUBPROJECT 1:

Project PID2020-112545RB-C51 funded by MCIN/ AEI /10.13039/501100011033

1. Analyisis of new architectures and radio enabling technologies for massive LEO architectures in bands above 60 GHz.

2. Development of new technologies for beam steering and reconfigurability for array antenna systems in Ka, Q, V bands and beyond based on liquid crystals technology and analog beamforming.

3. Identification and development of new digital antenna technologies and work scenarios in the area of terrestrial and space communcation as well as new techniques and algorithms for array processing including new capabilities and reconfigurable architectures.

4. Development of new antenna technologies measurement techniques in Ka, Q, V bands and beyond and improving the performance of the measurement systems in these bands.

Publications:

[1] J. Melendro-Jimenez, P. Sánchez Olivares, A. Tamayo Domínguez, X. Sun and J.M. Fernández González, “3D Printed Directive Beam-Steering Antenna Based on Gradient Index Flat Lens with an Integrated Polarizer for Dual Circular Polarization at W-band”, IEEE Trans. on Antennas and Propagation, DOI: 10.1109/TAP.2022.3217177, October 2022.

[2] A. Ertug Zorkun, M. A. Salas-Natera and R. Martínez Rodríguez-Osorio, “Improved Iterative Inverse Matrix Approximation Algorithm for Zero Forcing Precoding in Large Antenna Arrays”, IEEE Access, Vol. 10, pp. 100964-100975, DOI: 10.1109/ACCESS.2022.3208155, September 2022.

[3] A. Tamayo Domínguez, P. Sánchez Olivares, A. Camacho Hernández and J.M. Fernández González, “Guidelines for Accurate In-House Electroplating and 3D Printing Processes Applied to mm-Wave Devices”, IEEE Microwave and Wirless Components Letters, DOI: 10.1109/LMWC.2022.3182868, June 2022.

[4] F. Rodríguez Varela, B. Galocha Iragüen and M. Sierra Castañer, “Single-Cut Phaseless Near-Field Measurements for Fast Antenna Testing”, IEEE Trans. on Antennas and Propagation, DOI: 10.1109/TAP.2022.3177525, May 2022.

[5] D. Santiago, A. Tamayo Domínguez and M. A.G. Laso, T. Lopetegi, J.M. Fernández González, R. Martínez and I. Arregui, “Robust Design of 3D-Printed W-Band Bandpass Filters Using Gap Waveguide Technology”, J. Infrared Milli Terahz Waves, DOI: 10.1007/s10762-022-00903-0, 2023.

[6] J.A. Vásquez Peralvo, A. Tamayo Domínguez, G. Pérez Palomino, J.M. Fernández González and T. Wong, “3D Inductive Frequency Selective Structures Using Additive Manufacturing and Low Cost Metallization”, Sensors 2022, DOI: 10.3390/s22020552, 2022.

[7] A. Tamayo Domínguez, J.M. Fernández González and O. Quevedo Teruel, “Mechanically Reconfigurable Waveguide Filter Based on Glide Symmetry at Millimetre Wave”, Sensors 2022, DOI: 10.3390/s22031001, 2022.

SUBPROJECT 2: UVI-INTERSPACE

Measurement and Characterization of Radio Propagation Channel for Future Communication Ecosystem beyond 5G

OBJECTIVES SUBPROJECT 2:

Project PID2020-112545RB-C52 funded by MCIN/ AEI /10.13039/501100011033

1. Design and construction of two agile radio wideband channel sounders for satellite and terrestrial radio environment, rapidly changing and non-stationary, at millimetric band frequencies: Ka, Q, V and W band.

2. Measurement campaign in satellite and terrestrial environments in Ka, Q, V and W band.

3. OTA measurements with developed antennas in real environments.

4. Application of heuristic analysis to both the development of the channel sounder and measurement techniques.

5. Optimization of the estimated radio channel model and its simulation.

6. Study and development of compensation/mitigation techniques for impairments due to propagation mechanisms; determination of the Channel Enhancement Indicator achieved.

Publications:

[1] Luis A. López-Valcárcel, Manuel García Sánchez, “A Wideband Radio Channel Sounder for Non-Stationary Channels: Design, Implementation and Testing”, Electronics, vol. 10, no. 15, pp. 1838, 2021. DOI: https://doi.org/10.3390/electronics10151838

[2] Bram Decoster, Stephanie Maes, Iñigo Cuiñas, Manuel García Sánchez, Rafael Caldeirinha and Jo Verhaevert, “Dual-Band Single-Layer Fractal Frequency Selective Surface for 5G Applications”, Electronics, vol.10, no. 22, pp. 2880, 2021. DOI: https://doi.org/10.3390/electronics10222880

[3] Isabel Expósito Pérez, Cristian Martínez Portas, Manuel García Sánchez, Manuel Sierra Castañer, Iñigo Cuiñas Gómez, “Intercomparación de medida de antenas con reducido número de participante”, Libro de actas del XXXVI Simposio Nacional URSI 2021. 20-24 Septiembre 2021, Universidad de Vigo (España). Presentación oral.

[4] Fidel Alejandro Rodríguez-Corbo, Leyre Azpilicueta, Mikel Celaya-Echarri, Peio Lopez-Iturri, Ana Vázquez Alejos, Raed M. Shubair, Francisco Falcone, “Deterministic and Empirical Approach for Millimeter-Wave Complex Outdoor Smart Parking Solution Deployments”, Sensors, vol. 21, no. 12, pp. 4112, 2021. DOI: https://doi.org/10.3390/s21124112

[5] Fidel Alejandro Rodríguez-Corbo, Leyre Azpilicueta, Mikel Celaya-Echarri, Ana Vázquez Alejos, Francisco Falcone, “Propagation Models in Vehicular Communications”, IEEE Access, vol. 9, pp. 15902 – 15913, 2021. DOI: 10.1109/ACCESS.2021.3049884

[6] Miguel Riobó Prieto, Rob Hofman, Manuel García Sánchez, Íñigo Cuíñas, Isabel Expósito Pérez, Jo Verhaevert, “ Effect of Space Diversity for Fading Mitigation at 40 and 60 GHz Indoor Channels”, 16th European Conference on Antennas and Propagation (EuCAP), Madrid, Spain, March 27 – April 1, 2022. Presentación oral. DOI: 23919/EuCAP53622.2022.9769493

[7] Malo-Torreiro, M. Seijas-Iglesias, I. Cuiñas, “Comparison of Distribution Models for Fast Variations in the Indoor Radio Channel at 5G Frequency Range 1 Microwave Bands”, Electronics, vol. 11, no. 3, pp. 449, 2022. DOI: https://doi.org/10.3390/electronics11030449

[8] Manuel García Sánchez, Carlos Iglesias, Iñigo Cuiñas, and Isabel Expósito, “Building Penetration Losses at 3.5 GHz: Dependence on Polarization and Incidence Angle”, Electronics, vol. 12, no. 1, pp. 106, 2023. DOI: https://doi.org/10.3390/electronics12010106

[9] Leyre Azpilicueta, Cesar Vargas-Rosales, Ana Vazquez Alejos, Francisco Falcone, Chapter 7: “Vehicular Communications in the B5G Era”, Book title: “A Glimpse Beyond 5G in Wireless Networks”, Editorial Springer, ISSN: 978-3-031-13785-3, 2023. DOI: https://doi.org/10.1007/978-3-031-13786-0_7

SUBPROJECT 3: UPNA-INTERSPACE

Filters and Passive Components for the Future Integrated Terrestrial and Space-based Millimter Waves Radio Systems

OBJECTIVES SUBPROJECT 3:

Project PID2020-112545RB-C53 funded by MCIN/ AEI /10.13039/501100011033

1. Synthesis techniques for devices with smooth profile based on Inverse Scattering and their applications to planar circuits and rectangular waveguide technology.

2. Design of step-impedance filters with advanced frequency response in waveguide technology (wide passband and high selectivity).

3. Design of filters and passive components in contactless technologies such as the Groove Gap Waveguide (GGW) technology for simpler fabrications and enhanced performance at millimeter-waves and above.

4. Filters and passive components by advanced manufacturing techniques such as the 3D Screen Printing, SLM (Selective Laser Melting), micro SLM (or high precision SLM) or stereolithography (SLA).

 Publications:

[1] Abdul Sami, Miguel Angel Gomez Laso, Txema Lopetegi, Israel Arnedo, Ibai Calero, Fernando Teberio, Petronilo Martin Iglesias, David Benito, Ivan Arregui, “Integrating multiple stubs in stepped-impedance filter aiming for high selectivity,” Electronics Letters, July 2022, vol. 58, no. 14, pp. 554-556. Publicado en abierto (gold open access) en https://ietresearch.onlinelibrary.wiley.com/doi/10.1049/ell2.12517

[2] F. Teberio, I. Arregui, P. Martin-Iglesias, M. A. G. Laso, “New high manufacturing yield filter design methods and topologies for high-capacity satellites”, WS04 workshop “New Trends in Microwave and mmWave Filters” within the 51st European Microwave Conference 2021, London, 2-7 April 2022. Comunicación invitada.

[3] A. Sami, F. Teberio, I. Arnedo, P. Martin-Iglesias, T. Lopetegi, I. Arregui, M. A. G. Laso, “High-Performance Stepped-impedance Bandpass Filters for Millimeter-wave Applications”, 3rd URSI AT-AP-RASC, Gran Canaria, Spain, 29 May – 3 June 2022. Publicado en abierto (green open access) en https://doi.org/10.5281/zenodo.7343305.  Comunicación oral (online).

[4] D. Santiago, M.A.G. Laso, T. Lopetegi, I. Arregui, “Gap Waveguide Bandpass Filter with Reduced Height Pins for Easy Fabrication”, 3rd URSI AT-AP-RASC, Gran Canaria, Spain, 29 May – 3 June 2022. Publicado en abierto (green open access) en https://doi.org/10.5281/zenodo.7930515. Comunicación oral (online).

[5] Jabir Hussain, Jamil Ahmad, Ivan Arregui, Petronilo Martin-Iglesias, Israel Arnedo, Miguel A. G. Laso, Txema Lopetegi, “High-Power Performance of Smooth-Profiled Rectangular Waveguide Filters”, 2022 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO’2022), Limoges, France, July 6-8, 2022. Comunicación oral.

[6] D. Santiago, M. A. G. Laso, T. Lopetegi, I. Arregui, “Filtro paso banda en tecnología groove gap waveguide con altura de pines reducida para facilitar su fabricación”, Simposio Nacional URSI’2022, Málaga, 5-7 septiembre 2022. Publicación en abierto (green open access) en https://hdl.handle.net/2454/45363 (repositorio institucional UPNA). Comunicación oral.

[7] Abdul Sami, Iván Arregui, Txema Lopetegi, Fernando Teberio, Petronilo Martín-Iglesias, Miguel A. G. Laso, “High-Performance Stepped-Impedance Bandpass Filters for Microwave and Millimeter-wave Applications”, WM8 workshop “New techniques and foundations for microwave and mm-wave RF filtering devices for emerging communication systems” within the 52nd European Microwave Conference 2022, Milan, Italy, September 25-30, 2022.  Comunicación invitada.

[8] Jabir Hussain, Jamil Ahmad, Iván Arregui, Petronilo Martín-Iglesias, Israel Arnedo, Txema Lopetegi, Miguel A. G. Laso, “Smooth Profiled Rectangular Waveguide Filters”, 52nd European Microwave Conference 2022, Milan, Italy, September 25-30, 2022. Comunicación invitada.

[9] Jamil Ahmad, Jabir Hussain, Ivan Arregui, Petronilo Martin-Iglesias, Israel Arnedo, Miguel A. G. Laso, Txema Lopetegi, “Improvement of Corona Breakdown Threshold (Peak Power Handling) in Smooth-Profiled Microstrip Filters”, ESA International Workshop on Multipactor, Corona and Passive Intermodulation (MULCOPIM’22), Valencia, Spain, 19-21 October 2022. Publicación en abierto (green open access) en https://doi.org/10.5281/zenodo.8198958. Comunicación oral.

[10] A. Sami, F. Teberio, I. Arnedo, P. Martin-Iglesias, T. Lopetegi, M. A. G. Laso, I. Arregui, “Multipactor Breakdown Analysis of Ku-Band Meandered Low-Pass Filter”, ESA International Workshop on Multipactor, Corona and Passive Intermodulation (MULCOPIM’22), Valencia, Spain, 19-21 October 2022. Publicado en abierto (green open access) en https://academica-e.unavarra.es/handle/2454/44390 (repositorio institucional UPNA). Comunicación oral.

[11] Beatriz Aja, Sergio Arguedas Cuendis, Ivan Arregui, Eduardo Artal, R. Belén Barreiro, Francisco J. Casas, Marina C. de Ory, Alejandro Díaz-Morcillo, Luisa de la Fuente, Juan Daniel Gallego, Jose María García-Barceló, Benito Gimeno, Alicia Gomez, Daniel Granados, Bradley J. Kavanagh, Miguel A.G. Laso, Txema Lopetegi, Antonio José Lozano-Guerrero, Maria T. Magaz, Jesús Martín-Pintado, Enrique Martínez-González, Jordi Miralda-Escudé, Juan Monzó-Cabrera, Francisco Najarro de la Parra, Jose R. Navarro-Madrid, Ana B. Nuñez Chico, Juan Pablo Pascual, Jorge Pelegrin, Carlos Peña Garay, David Rodriguez, Juan M. Socuéllamos, Fernando Teberio, Jorge Teniente, Patricio Vielva, Iván Vila, Rocío Vilar, Enrique Villa, “ The Canfranc Axion Detection Experiment (CADEx): search for axions at 90 GHz with Kinetic Inductance Detectors” Journal of Cosmology and Astroparticle Physics, Volume 2022, November 2022, JCAP11(2022)044, doi: 10.1088/1475-7516/2022/11/044. Publicado en abierto (green open access) en https://hdl.handle.net/2454/45319 (repositorio institucional UPNA).

[12] P. Martín-Iglesias, M. Marechal, P. Calves, M. Hazard, L. Pambaguian, A. Brandao, S. Rodriguez Castillo, T. Martin, J. Percaz, V. Iza, S. Martín-Iglesias, I. Arregui, F. Teberio, T. Lopetegi, M. A. G. Laso, “Metal 3D printing for RF/microwave high-frequency parts” CEAS Space J 15, 7–25 (2023), doi: 10.1007/s12567-022-00447-y. Publicado en abierto (green open access) en https://academica-e.unavarra.es/handle/2454/43217 (repositorio institucional UPNA)

[13] David Santiago, Adrián Tamayo-Domínguez, Miguel A. G. Laso, Txema Lopetegi, José-Manuel Fernández-González, Ramón Martínez, Iván Arregui, “Robust Design of 3D-Printed W-Band Bandpass Filters Using Gap Waveguide Technology” J Infrared Milli Terahz Waves 44, 98–109 (2023), doi: 10.1007/s10762-022-00903-0. Publicado en abierto (gold open access) en https://link.springer.com/article/10.1007/s10762-022-00903-0. Este artículo es una colaboración entre UPM y UPNA.

[14] Jon M. Percaz, Jabir Hussain, Ivan Arregui, Fernando Teberio, David Benito, Petronilo Martin-Iglesias, Israel Arnedo, Miguel A. G. Laso, Txema Lopetegi, “Synthesis of Rectangular Waveguide Filters With Smooth Profile Oriented to Direct Metal Additive Manufacturing” IEEE Transactions on Microwave Theory and Techniques, aceptado para publicación en 2023, doi: 10.1109/TMTT.2023.3245683. Publicado en abierto (gold open access) en https://ieeexplore.ieee.org/document/10056389

[15] David Santiago, Miguel A. G. Laso, Txema Lopetegi, Ivan Arregui, “Gap waveguide topology with reduced-height pins for millimeter-wave components” URSI Radio Science Letters, URSI Radio Science Letters, vol. 4, 2022. Publicado en abierto (gold open access) en https://doi.org/10.46620/22-0029.

[16] D. Santiago, A. Tamayo-Domínguez, M. A. G. Laso, T. Lopetegi, J. M. Fernández-González, R. Martínez, I. Arregui, “A 94-GHz SLA-enabled bandpass filter for monopulse radar in space debris detection”, URSI GASS 2023, Sapporo, Japan, 19 – 26 August 2023. Publicado en abierto (green open access) en https://doi.org/10.5281/zenodo.10433123 Este artículo es una colaboración entre UPM y UPNA.  Comunicación oral.

[17] J. Ahmad, J. Hussain, I. Arregui, P. Martin-Iglesias, I. Arnedo, Miguel A. G. Laso, and Txema Lopetegi, “Enhancement of the Peak Power Handling Capability in Microstrip Filters by Employing Smooth-Profiled Conductor Strips” Progress In Electromagnetics Research C, Vol. 133, 219–231, 2023. Publicado en abierto (gold open access) en https://www.jpier.org/issues/volume.html?paper=23040602.

[18] D. Santiago, M.A.G. Laso, T. Lopetegi, and I. Arregui, “Novel Design Method for Millimeter-wave Gap Waveguide Low-Pass Filters Using Advanced Manufacturing Techniques” IEEE Access, vol. 11, 2023. Publicado en abierto (gold open access) en https://ieeexplore.ieee.org/document/10223221.

[19] M.A.G. Laso, A. Sami, T. Lopetegi, P. Martin-Iglesias, G.A. Álvarez-Botero, A. Pons-Abenza, I. Arregui, “Integración de múltiples stubs en filtros de saltos de impedancias de alta selectividad” Simposio Nacional URSI’2023, Cáceres, 13-15 septiembre 2023. Publicación en abierto (green open access) en https://hdl.handle.net/2454/47146 (repositorio institucional UPNA). Comunicación oral.

[20] D. Santiago, A. Tamayo-Domínguez, M.A.G. Laso, T. Lopetegi, J.-M. Fernández-González, R. Martínez, I. Arregui, “Diseño robusto de filtros paso-banda de banda W en tecnología Gap Waveguide impresos en 3D” Simposio Nacional URSI’2023, Cáceres, 13-15 septiembre 2023. Publicación en abierto (green open access) en https://hdl.handle.net/2454/47147 (repositorio institucional UPNA). Este artículo es una colaboración entre UPM y UPNA. Comunicación oral.

[21] S. García-Martínez, D. Santiago, A. Tamayo-Domínguez, P. Sánchez-Olivares, I. Arregui, T. Lopetegi, J. M. Fernández-González, M. A. G. Laso, “Diseño de Filtro en Guía de Onda en Banda W Mediante Guía Multicapa con Simetría Glide” Simposio Nacional URSI’2023, Cáceres, 13-15 septiembre 2023. Este artículo es una colaboración entre UPM y UPNA. Comunicación oral.

SUBPROJECT 4: UGR-INTERSPACE

New Electronically Reconfigurable Antenna Technology based on Field Confinement for Future Communication systems beyond 5G

OBJECTIVES SUBPROJECT 4:

Project PID2020-112545RB-C54 funded by MCIN/ AEI /10.13039/501100011033

1. Development of design techniques and procedures for fiel-confinement-based devices in Ka, Q, V bands and beyond. Exploration of the design of radiating devices for frequencies beyond W band (up to 330 GHz).

2. Addition of reconfigurability to passive devices based on graphene and graphene-based materials.

3. Development of new techniques for emulation the channel propagation on hybrid reverberation chamber. Exploratory study of the propagation channel performance for frequencies beyond W band.

4. Improvement of the manufacturing capabilities for initial prototypes, reducing the time required for the prototyping cycle.

5. Increase and improvement of the 5G-Lab mesuring capabilities, also maximizing transfer to industry through the offer of mesuring services to companies and research centers.

Publications:

[1] Ignacio Parellada-Serrano, Mario Pérez-Escribano, Carlos Molero, Pablo Padilla, Valentín De la Rubia “Three-Dimensional Fully Metallic Dual Polarization Frequency Selective Surface Design Using Coupled-Resonator Circuit Information”. IEEE Transactions on Antennas and Propagation. 2024.

[2] Mario Pérez-Escribano, Angel Palomares-Caballero, Pablo Padilla, Juan F Valenzuela-Valdés, Enrique Márquez-Segura. “Broadband parasitic modeling of diodes in the millimeter-wave band”. AEU-International Journal of Electronics and Communications. 2024.

[3] Ángel Palomares-Caballero, Carlos Molero, Pablo Padilla, María García-Vigueras, Raphaël Gillard. “Wideband 3-D-Printed Metal-only Reflectarray for Controlling Orthogonal Linear Polarizations”. IEEE Transactions on Antennas and Propagation. 2023.

[4] Angel Palomares-Caballero, Carlos Molero, Farshad Rostami Ghadi, F Javier López-Martínez, Pablo Padilla, David Morales-Jimenez, Juan F Valenzuela-Valdés “Enabling intelligent omni-surfaces in the polarization domain: Principles, implementation and applications”. IEEE Communications Magazine. Vol 61 Nª 11. 2023.

[5] Mario Pérez-Escribano, Salvador Moreno-Rodríguez, Carlos Molero, Juan F Valenzuela-Valdés, Pablo Padilla, Antonio Alex-Amor. “Analytical Framework to Model Reconfigurable Metasurfaces including Lumped Elements.” IEEE Transactions on Circuits and Systems II: Express Briefs. 2023.

[6] Salvador Moreno-Rodríguez, Antonio Alex-Amor, Pablo Padilla, Juan F Valenzuela-Valdés, Carlos Molero. “Time-periodic metallic metamaterials defined by floquet circuits”. IEEE Access. 2023. 

[7] Antonio Alex-Amor, Salvador Moreno-Rodríguez, Pablo Padilla, Juan F Valenzuela-Valdés, Carlos Molero “Analytical equivalent circuits for three-dimensional metamaterials and metagratings”. Physical Review Applied. Vol 20. Nº4. 2023. 

[8] A. Ramírez-Arroyo, A. Alex-Amor, P. Padilla, J. F. Valenzuela-Valdés, “Joint Direction-of-Arrival and Time-of-Arrival Estimation with Ultra-wideband Elliptical Arrays,” IEEE TAP, 2023.

[9] Á. Palomares-Caballero, C. Molero Jiménez, P. Padilla, M. García-Viguerasand R. Gillard, “Wideband Metal-only Reflectarray for Controlling Orthogonal Polarizations” IEEE TAP, 2023.

[10] A. Biedma-Pérez, P. Padilla, C. Segura-Gómez, Á. Palomares-Caballero, “Holey SIW Horn Antenna Based on an H-plane Lens-wise Wavefront Collimation”, IEEE TAP, 2023.

[11] C. Segura-Gómez, Á. Palomares-Caballero, P. Padilla, “A 1-to-8 Fully Modular Stacked SIW Antenna Array for Millimeter-Wave Applications”, IEEE TAP, 2022. 

[12] Á. Palomares-Caballero, C. Megías, C. Molero, A. Alex-Amor and P. Padilla, “Wideband Gap-Waveguide Phase Shifter Based on a Glide-Symmetric Ridge,” in IEEE Microwave and Wireless Components Letters, 2022.

[13] S. Moreno-Rodríguez, M.A. Balmaseda-Márquez, J. Carmona-Murillo, and Á. Palomares-Caballero, “Polarization-Insensitive Unit Cells for a Cost-Effective Design of a 3-D-Printed Fresnel-Lens Antenna” Electronics 11, 2022.  

[14] A. Alex-Amor, Á. Palomares-Caballero, C. Molero, “3-D Metamaterials: Trends on Applied Designs, Computational Methods and Fabrication Techniques”, Electronics 11 (3), 2022.

[15] Á. Palomares-Caballero, A. Alex-Amor, J. Valenzuela-Valdés and P. Padilla, “Millimeter-Wave 3-D-Printed Antenna Array Based on Gap-Waveguide Technology and Split E-Plane Waveguide,” in IEEE Transactions on Antennas and Propagation, 2021. 

[16] C. Molero et al., “Metamaterial-Based Reconfigurable Intelligent Surface: 3D Meta-Atoms Controlled by Graphene Structures,” in IEEE Communications Magazine, 2021.

[17] J Velasco, I Parellada-Serrano, C Molero, “Fully metallic reflectarray for the ku-band based on a 3D architecture”, Electronics 10 (21), 2021.

[18] A. Ramírez-Arroyo, A. Alex-Amor, C. García-García, Á. Palomares-Caballero, P. Padilla and J. F. Valenzuela-Valdés, “Time-Gating Technique for Recreating Complex Scenarios in 5G Systems,” IEEE Access, vol. 8, pp. 183583-183595, 2020. 

[19] Á. Palomares-Caballero, A. Alex-Amor, P. Padilla and J. F. Valenzuela-Valdés, “Dispersion and Filtering Properties of Rectangular Waveguides Loaded With Holey Structures,” in IEEE Transactions on Microwave Theory and Techniques, vol. 68, no. 12, pp. 5132-5144, Dec. 2020.

[20] Á. Palomares-Caballero, A. Alex-Amor, P. Escobedo, J. Valenzuela-Valdés and P. Padilla, “Low-Loss Reconfigurable Phase Shifter in Gap-Waveguide Technology for mm-Wave Applications,” in IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 67, no. 12, pp. 3058-3062, Dec. 2020. 

[21] C Segura-Gómez, Á Palomares-Caballero, A Alex-Amor, JF Valenzuela-Valdés, P Padilla, “Modular Design for a Stacked SIW Antenna Array at Ka-Band”, IEEE Access 8, 2020.