Aperture Antennas for Millimeter and Sub-Millimeter Wave Applications, 2017
Millimeter-wave antenna systems have traditionally required high performance feeds in order to fu... more Millimeter-wave antenna systems have traditionally required high performance feeds in order to fulfill its stringent requirements. Therefore, this goal has been achieved by corrugated horns. However, in the last years new applications mainly in the communication systems have driven the use of other types of antenna feed with slightly reduced performance but simpler manufacturing at mm-wave and submm-wave frequencies with improvements in cost reduction. These advanced profiles are usually based in smooth waveguide advanced profiles. Besides, the chapter describes different feed configurations based on metamaterial structures and several examples of metamaterial based or inspired antennas are considered. Then, this chapter covers the different alternatives currently used for mm-wave antenna feed: corrugated horns, spline horns, and metamaterial horns. At the end of each section, it includes some research successful results.
This paper presents a novel pixel geometry for the implementation of metasurfaces requiring synch... more This paper presents a novel pixel geometry for the implementation of metasurfaces requiring synchronized phase propagation of transverse magnetic (TM) and transverse electric (TE) modes. The pixel is composed by an elliptical metallic patch with an asymmetric cross-shaped aperture in the center, printed on a grounded slab. A practical implementation of a metasurface was carried out employing such a pixel geometry. Simulation results show similar frequency dispersion properties for both modes within the working frequency band, in agreement with the theoretical basis.
This paper studies the surface modes at the interface of finite size Electromagnetic Band Gap (EB... more This paper studies the surface modes at the interface of finite size Electromagnetic Band Gap (EBG) woodpile structures. The impact of different types of woodpile terminations on the properties of these surface modes is analyzed. For all the studied terminations there exist surface modes which must be taken into account when designing components based on this EBG structure.
IEEE Transactions on Antennas and Propagation, 2018
The experimental validation of a Ku-band dualcircularly polarized (CP) broadside-beam metasurface... more The experimental validation of a Ku-band dualcircularly polarized (CP) broadside-beam metasurface (MTS) antenna is presented. A radially modulated anisotropic singlelayer MTS has been synthesised employing subwavelength elliptical slotted metallic patches printed on top of a thin Arlon grounded substrate. In the structure, two decoupled phasematched transverse magnetic and transverse electric surface waves (SWs) are excited, which interact with the modulated surface leading to a CP broadside radiation. Two different orthomode transducers have been designed to excite the SWs with orthogonal polarization and equal amplitude. The first feeding system is composed of a metallic stepped septum inside an airfilled square waveguide. A conical section is included to match the output port of the square waveguide with the terminal, dielectric filled circular waveguide. The second feed is much more compact and efficient, and it is composed of a circular waveguide completely filled by a dielectric. Depending on the input port excited on the feeds, two TE 11 modes are excited with ±90°phase shift, which determine the right-hand or left-hand sense of the broadside beam generated by the MTS. Manufacturing details of the MTS and excitations are given, and the measurements are compared with the simulation results. Finally, conclusions are drawn.
IEEE Antennas and Wireless Propagation Letters, 2018
In this work, a study of the performance of several antennas and components, manufactured using a... more In this work, a study of the performance of several antennas and components, manufactured using an accurate stereolithography 3D printer and resin for maximum accuracy and detail, is carried out. Electroless plating of the components to cover the pieces with a thick copper layer to improve their mechanical resistance is undertaken. Several SatCom horn antennas and components are designed, manufactured, and tested. A detailed study of a spline horn antenna and a filter is covered. These results are compared to the metallic lathe manufactured versions. Conclusions are derived from these tests, which are useful to improve additive manufactured components in future versions.
IEEE Transactions on Antennas and Propagation, 2016
This paper presents the design of a modulated metasurface (MTS) antenna capable to provide both r... more This paper presents the design of a modulated metasurface (MTS) antenna capable to provide both right-hand (RH) and left-hand (LH) circularly polarized (CP) boresight radiation at Ku-band (13.5GHz). This antenna is based on the interaction of two cylindrical-wavefront surface wave (SW) modes of TE and TM types with a rotationally symmetric, anisotropic modulated MTS placed on top of a grounded slab. A properly designed centered circular waveguide-feed excites the two orthogonal (decoupled) SW modes and guarantees the balance of the power associated with each of them. By a proper selection of the anisotropy and modulation of the MTS pattern, the phase velocities of the two modes are synchronized and leakage is generated in broadside direction with two orthogonal linear polarizations. When the circular waveguide is excited with two mutually orthogonal TE 11 modes in phase-quadrature, an LHCP or RHCP antenna is obtained. This paper explains the feeding system and the MTS requirements that guarantee balanced conditions of the TM/TE SWs and consequent generation of dual circularly polarized boresight radiation.
Journal of Infrared, Millimeter, and Terahertz Waves, 2016
Monitoring grapevine water status by means of measuring the reflectivity at the trunk in the tera... more Monitoring grapevine water status by means of measuring the reflectivity at the trunk in the terahertz band is presented. A grapevine is located inside a growth chamber to simulate diverse outdoor conditions and correlate them with variations produced in the reflected signal of the trunk. Modifications of light conditions, temperature, and irrigation of the grapevine are recorded either in time domain broadband measurements as well as in the magnitude and phase of narrowband measurements in the frequency domain. The results are compared with traditional techniques using a dendrometer and a humidity probe with excellent agreement.
The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancemen... more The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancement are discussed in detail. Experiments using cucumber (Cucumis sativus) plants show that the shoot growth enhancement caused by a structurally well-characterized humic acid with sedimentary origin is functionally associated with significant increases in abscisic acid (ABA) root concentration and root hydraulic conductivity. Complementary experiments involving a blocking agent of cell wall pores and water root transport (polyethylenglycol) show that increases in root hydraulic conductivity are essential in the shoot growth-promoting action of the model humic acid. Further experiments involving an inhibitor of ABA biosynthesis in root and shoot (fluridone) show that the humic acid-mediated enhancement of both root hydraulic conductivity and shoot growth depended on ABA signaling pathways. These experiments also show that a significant increase in the gene expression of the main root plasma membrane aquaporins is associated with the increase of root hydraulic conductivity caused by the model humic acid. Finally, experimental data suggest that all of these actions of model humic acid on root functionality, which are linked to its beneficial action on plant shoot growth, are likely related to the conformational structure of humic acid in solution and its interaction with the cell wall at the root surface. Numerous studies have illustrated the relevant role of dissolved organic matter (DOM) present in soil solution and aquatic reservoirs (lakes, rivers, etc.) in the biological and chemical evolution of both natural and anthropogenic ecosystems (
Quality control systems in industry can benefit from the new possibilities offered by the THz fre... more Quality control systems in industry can benefit from the new possibilities offered by the THz frequency range. THz imaging systems can complement actual quality control systems and at the same time offer new information about products, improving quality and reducing costs. In this case we have implemented an imaging system to control the evolution of water content in leaves. The
2012 IEEE International Workshop on Antenna Technology (iWAT), 2012
Global transmission communication systems from geostationary orbit require compact and light ante... more Global transmission communication systems from geostationary orbit require compact and light antennas to reduce as much as possible the overall mass of the on flight configuration. Within the frame of the ESA project Compact Low-Mass Global Antennas, EADS CASA Espacio and the Public University of Navarra are developing a light and compact C-band antenna with dual circular polarization. The design
2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2013
ABSTRACT In this paper a compact and light antenna with dual circular polarization based on Elect... more ABSTRACT In this paper a compact and light antenna with dual circular polarization based on Electromagnetic Band Gap (EBG) superstrate technology capable to fulfill the specific radiofrequency (RF) requirements of a C-Band geostationary TT&C telecommunication satellite system, working simultaneously at 3.7GHz and 4.2GHz is presented. The EBG superstrate is composed by a metallic sheet with holes and equally distanced ring and jerusalem cross shaped metallic elements. The proposed low mass system represents an advantageous alternative to the bulky horn antennas usually used for TT&C operations in current satellites.
This paper deals with the use of Electromagnetic Band gap-based high-efficiency planar ceramic an... more This paper deals with the use of Electromagnetic Band gap-based high-efficiency planar ceramic antennas. The improvement of the overall performances with respect to the use of a standard high dielectric substrate is shown. Good impedance matching and radiation performances are obtained in addition to a reasonably high efficiency with values over 50% at the operational frequency. The antenna has been breadboarded and measured and good agreement has been obtained between simulations and measurements.
IEEE Transactions on Antennas and Propagation, 2009
Two different electromagnetic bandgap (EBG) superstrate array antenna configurations, intended fo... more Two different electromagnetic bandgap (EBG) superstrate array antenna configurations, intended for the wide area augmentation service space segment, are presented in this paper. The described antenna configurations take advantage of the directivity enhancement produced by a semireflective sheet placed parallel to a metallic ground plane. The first design presented is realized using a 2times2 circularly polarized (CP) patch array illuminating
IEEE Transactions on Antennas and Propagation, 2007
A thin artificial magnetic conductor (AMC) structure is designed and breadboarded for radar cross... more A thin artificial magnetic conductor (AMC) structure is designed and breadboarded for radar cross-section (RCS) Reduction applications. The design presented in this paper shows the advantage of geometrical simplicity while simultaneously reducing the overall thickness (for the current design 16). The design is very pragmatic and is based on a combination of AMC and perfect electric conductor (PEC) cells in a chessboard like configuration. An array of Sievenpiper's mushrooms constitutes the AMC part, while the PEC part is formed by full metallic patches. Around the operational frequency of the AMC-elements, the reflection of the AMC and PEC have opposite phase, so for any normal incident plane wave the reflections cancel out, thus reducing the RCS. The same applies to specular reflections for off-normal incidence angles. A simple basic model has been implemented in order to verify the behavior of this structure, while Ansoft-HFSS software has been used to provide a more thorough analysis. Both bistatic and monostatic measurements have been performed to validate the approach.
Aperture Antennas for Millimeter and Sub-Millimeter Wave Applications, 2017
Millimeter-wave antenna systems have traditionally required high performance feeds in order to fu... more Millimeter-wave antenna systems have traditionally required high performance feeds in order to fulfill its stringent requirements. Therefore, this goal has been achieved by corrugated horns. However, in the last years new applications mainly in the communication systems have driven the use of other types of antenna feed with slightly reduced performance but simpler manufacturing at mm-wave and submm-wave frequencies with improvements in cost reduction. These advanced profiles are usually based in smooth waveguide advanced profiles. Besides, the chapter describes different feed configurations based on metamaterial structures and several examples of metamaterial based or inspired antennas are considered. Then, this chapter covers the different alternatives currently used for mm-wave antenna feed: corrugated horns, spline horns, and metamaterial horns. At the end of each section, it includes some research successful results.
This paper presents a novel pixel geometry for the implementation of metasurfaces requiring synch... more This paper presents a novel pixel geometry for the implementation of metasurfaces requiring synchronized phase propagation of transverse magnetic (TM) and transverse electric (TE) modes. The pixel is composed by an elliptical metallic patch with an asymmetric cross-shaped aperture in the center, printed on a grounded slab. A practical implementation of a metasurface was carried out employing such a pixel geometry. Simulation results show similar frequency dispersion properties for both modes within the working frequency band, in agreement with the theoretical basis.
This paper studies the surface modes at the interface of finite size Electromagnetic Band Gap (EB... more This paper studies the surface modes at the interface of finite size Electromagnetic Band Gap (EBG) woodpile structures. The impact of different types of woodpile terminations on the properties of these surface modes is analyzed. For all the studied terminations there exist surface modes which must be taken into account when designing components based on this EBG structure.
IEEE Transactions on Antennas and Propagation, 2018
The experimental validation of a Ku-band dualcircularly polarized (CP) broadside-beam metasurface... more The experimental validation of a Ku-band dualcircularly polarized (CP) broadside-beam metasurface (MTS) antenna is presented. A radially modulated anisotropic singlelayer MTS has been synthesised employing subwavelength elliptical slotted metallic patches printed on top of a thin Arlon grounded substrate. In the structure, two decoupled phasematched transverse magnetic and transverse electric surface waves (SWs) are excited, which interact with the modulated surface leading to a CP broadside radiation. Two different orthomode transducers have been designed to excite the SWs with orthogonal polarization and equal amplitude. The first feeding system is composed of a metallic stepped septum inside an airfilled square waveguide. A conical section is included to match the output port of the square waveguide with the terminal, dielectric filled circular waveguide. The second feed is much more compact and efficient, and it is composed of a circular waveguide completely filled by a dielectric. Depending on the input port excited on the feeds, two TE 11 modes are excited with ±90°phase shift, which determine the right-hand or left-hand sense of the broadside beam generated by the MTS. Manufacturing details of the MTS and excitations are given, and the measurements are compared with the simulation results. Finally, conclusions are drawn.
IEEE Antennas and Wireless Propagation Letters, 2018
In this work, a study of the performance of several antennas and components, manufactured using a... more In this work, a study of the performance of several antennas and components, manufactured using an accurate stereolithography 3D printer and resin for maximum accuracy and detail, is carried out. Electroless plating of the components to cover the pieces with a thick copper layer to improve their mechanical resistance is undertaken. Several SatCom horn antennas and components are designed, manufactured, and tested. A detailed study of a spline horn antenna and a filter is covered. These results are compared to the metallic lathe manufactured versions. Conclusions are derived from these tests, which are useful to improve additive manufactured components in future versions.
IEEE Transactions on Antennas and Propagation, 2016
This paper presents the design of a modulated metasurface (MTS) antenna capable to provide both r... more This paper presents the design of a modulated metasurface (MTS) antenna capable to provide both right-hand (RH) and left-hand (LH) circularly polarized (CP) boresight radiation at Ku-band (13.5GHz). This antenna is based on the interaction of two cylindrical-wavefront surface wave (SW) modes of TE and TM types with a rotationally symmetric, anisotropic modulated MTS placed on top of a grounded slab. A properly designed centered circular waveguide-feed excites the two orthogonal (decoupled) SW modes and guarantees the balance of the power associated with each of them. By a proper selection of the anisotropy and modulation of the MTS pattern, the phase velocities of the two modes are synchronized and leakage is generated in broadside direction with two orthogonal linear polarizations. When the circular waveguide is excited with two mutually orthogonal TE 11 modes in phase-quadrature, an LHCP or RHCP antenna is obtained. This paper explains the feeding system and the MTS requirements that guarantee balanced conditions of the TM/TE SWs and consequent generation of dual circularly polarized boresight radiation.
Journal of Infrared, Millimeter, and Terahertz Waves, 2016
Monitoring grapevine water status by means of measuring the reflectivity at the trunk in the tera... more Monitoring grapevine water status by means of measuring the reflectivity at the trunk in the terahertz band is presented. A grapevine is located inside a growth chamber to simulate diverse outdoor conditions and correlate them with variations produced in the reflected signal of the trunk. Modifications of light conditions, temperature, and irrigation of the grapevine are recorded either in time domain broadband measurements as well as in the magnitude and phase of narrowband measurements in the frequency domain. The results are compared with traditional techniques using a dendrometer and a humidity probe with excellent agreement.
The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancemen... more The physiological and metabolic mechanisms behind the humic acid-mediated plant growth enhancement are discussed in detail. Experiments using cucumber (Cucumis sativus) plants show that the shoot growth enhancement caused by a structurally well-characterized humic acid with sedimentary origin is functionally associated with significant increases in abscisic acid (ABA) root concentration and root hydraulic conductivity. Complementary experiments involving a blocking agent of cell wall pores and water root transport (polyethylenglycol) show that increases in root hydraulic conductivity are essential in the shoot growth-promoting action of the model humic acid. Further experiments involving an inhibitor of ABA biosynthesis in root and shoot (fluridone) show that the humic acid-mediated enhancement of both root hydraulic conductivity and shoot growth depended on ABA signaling pathways. These experiments also show that a significant increase in the gene expression of the main root plasma membrane aquaporins is associated with the increase of root hydraulic conductivity caused by the model humic acid. Finally, experimental data suggest that all of these actions of model humic acid on root functionality, which are linked to its beneficial action on plant shoot growth, are likely related to the conformational structure of humic acid in solution and its interaction with the cell wall at the root surface. Numerous studies have illustrated the relevant role of dissolved organic matter (DOM) present in soil solution and aquatic reservoirs (lakes, rivers, etc.) in the biological and chemical evolution of both natural and anthropogenic ecosystems (
Quality control systems in industry can benefit from the new possibilities offered by the THz fre... more Quality control systems in industry can benefit from the new possibilities offered by the THz frequency range. THz imaging systems can complement actual quality control systems and at the same time offer new information about products, improving quality and reducing costs. In this case we have implemented an imaging system to control the evolution of water content in leaves. The
2012 IEEE International Workshop on Antenna Technology (iWAT), 2012
Global transmission communication systems from geostationary orbit require compact and light ante... more Global transmission communication systems from geostationary orbit require compact and light antennas to reduce as much as possible the overall mass of the on flight configuration. Within the frame of the ESA project Compact Low-Mass Global Antennas, EADS CASA Espacio and the Public University of Navarra are developing a light and compact C-band antenna with dual circular polarization. The design
2013 IEEE Antennas and Propagation Society International Symposium (APSURSI), 2013
ABSTRACT In this paper a compact and light antenna with dual circular polarization based on Elect... more ABSTRACT In this paper a compact and light antenna with dual circular polarization based on Electromagnetic Band Gap (EBG) superstrate technology capable to fulfill the specific radiofrequency (RF) requirements of a C-Band geostationary TT&C telecommunication satellite system, working simultaneously at 3.7GHz and 4.2GHz is presented. The EBG superstrate is composed by a metallic sheet with holes and equally distanced ring and jerusalem cross shaped metallic elements. The proposed low mass system represents an advantageous alternative to the bulky horn antennas usually used for TT&C operations in current satellites.
This paper deals with the use of Electromagnetic Band gap-based high-efficiency planar ceramic an... more This paper deals with the use of Electromagnetic Band gap-based high-efficiency planar ceramic antennas. The improvement of the overall performances with respect to the use of a standard high dielectric substrate is shown. Good impedance matching and radiation performances are obtained in addition to a reasonably high efficiency with values over 50% at the operational frequency. The antenna has been breadboarded and measured and good agreement has been obtained between simulations and measurements.
IEEE Transactions on Antennas and Propagation, 2009
Two different electromagnetic bandgap (EBG) superstrate array antenna configurations, intended fo... more Two different electromagnetic bandgap (EBG) superstrate array antenna configurations, intended for the wide area augmentation service space segment, are presented in this paper. The described antenna configurations take advantage of the directivity enhancement produced by a semireflective sheet placed parallel to a metallic ground plane. The first design presented is realized using a 2times2 circularly polarized (CP) patch array illuminating
IEEE Transactions on Antennas and Propagation, 2007
A thin artificial magnetic conductor (AMC) structure is designed and breadboarded for radar cross... more A thin artificial magnetic conductor (AMC) structure is designed and breadboarded for radar cross-section (RCS) Reduction applications. The design presented in this paper shows the advantage of geometrical simplicity while simultaneously reducing the overall thickness (for the current design 16). The design is very pragmatic and is based on a combination of AMC and perfect electric conductor (PEC) cells in a chessboard like configuration. An array of Sievenpiper's mushrooms constitutes the AMC part, while the PEC part is formed by full metallic patches. Around the operational frequency of the AMC-elements, the reflection of the AMC and PEC have opposite phase, so for any normal incident plane wave the reflections cancel out, thus reducing the RCS. The same applies to specular reflections for off-normal incidence angles. A simple basic model has been implemented in order to verify the behavior of this structure, while Ansoft-HFSS software has been used to provide a more thorough analysis. Both bistatic and monostatic measurements have been performed to validate the approach.
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Papers by Carlos Iriarte