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N. van Rooijen
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Wireless Radio Frequency (RF) systems have revolutionized the way we transmit and receive information from mobile platforms. In recent decades, the number of applications relying on wireless technologies, including telecommunications, radar, and sensing, have exploded. RF engineers have pushed the technological boundaries to feed our appetite for more information through the wireless networks. However, congestion in the low-frequency radio spectrum means that applications are in a continuous battle to be as spectrally efficient in the frequency bands allocated to them. This strategy has worked well for many wireless generations, but has added considerable challenges due to increased system complexity and decaying energy efficiency.....
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Wireless Radio Frequency (RF) systems have revolutionized the way we transmit and receive information from mobile platforms. In recent decades, the number of applications relying on wireless technologies, including telecommunications, radar, and sensing, have exploded. RF engineers have pushed the technological boundaries to feed our appetite for more information through the wireless networks. However, congestion in the low-frequency radio spectrum means that applications are in a continuous battle to be as spectrally efficient in the frequency bands allocated to them. This strategy has worked well for many wireless generations, but has added considerable challenges due to increased system complexity and decaying energy efficiency.....
This work describes the design of sub-Terahertz lens antennas that are coupled in the near field. The lenses have a flat interface, making them suitable for material characterization under plane wave incidence. A waveguide-based leaky-wave antenna feed illuminates the lenses efficiently with a Gaussian pattern over a bandwidth of 140 to 220 GHz. Then, a large permittivity hyperboloid lens converts the feed pattern into a plane wave with high Gaussicity. The use of dense dielectric materials significantly reduces field spreading effects when compared to setups with free-space propagation. Furthermore, the final lens architecture presents a flat interface, enabling direct lens-to-lens coupling for 2-port measurements with only −3 dB of coupling loss. This way, a quasi-optical Thru-Reflect-Line calibration can be performed, thereby making accurate extraction of material properties via full S-parameter matrix possible. Two materials were studied with this technique in a full-wave simulation, showcasing errors below 1 percent for permittivity and 2 percent for loss tangent, using a standard plane-wave propagation model.
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This work describes the design of sub-Terahertz lens antennas that are coupled in the near field. The lenses have a flat interface, making them suitable for material characterization under plane wave incidence. A waveguide-based leaky-wave antenna feed illuminates the lenses efficiently with a Gaussian pattern over a bandwidth of 140 to 220 GHz. Then, a large permittivity hyperboloid lens converts the feed pattern into a plane wave with high Gaussicity. The use of dense dielectric materials significantly reduces field spreading effects when compared to setups with free-space propagation. Furthermore, the final lens architecture presents a flat interface, enabling direct lens-to-lens coupling for 2-port measurements with only −3 dB of coupling loss. This way, a quasi-optical Thru-Reflect-Line calibration can be performed, thereby making accurate extraction of material properties via full S-parameter matrix possible. Two materials were studied with this technique in a full-wave simulation, showcasing errors below 1 percent for permittivity and 2 percent for loss tangent, using a standard plane-wave propagation model.
This work presents an electrically-small lens that has been redesigned towards a flat interface. This way, the lens is easier to integrated, compared to an earlier introduced spherical core-shell lens concept. The lens is created from a single dielectric host material by conformally machining holes into the material. In this process, two artificial dielectric layers are created; The first layer is used for anti-reflection purposes, whereas the second is used to convert the spherical interface to a flat interface. The two layers enable the use of holes with lower aspect ratio drilling, compared to classical gradient-index lenses. The lens is designed to operate in the 140-170 GHz bandwidth, and a prototype with height of only 2.2 mm and diameter of 6.6 mm was fabricated and characterize. The prototype is small enough to fit in many integrated circuit packages. The flat lens was compared to a non-flat core lens in terms of pattern quality, return loss and dielectric loss, with only negligible performance degradation.
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This work presents an electrically-small lens that has been redesigned towards a flat interface. This way, the lens is easier to integrated, compared to an earlier introduced spherical core-shell lens concept. The lens is created from a single dielectric host material by conformally machining holes into the material. In this process, two artificial dielectric layers are created; The first layer is used for anti-reflection purposes, whereas the second is used to convert the spherical interface to a flat interface. The two layers enable the use of holes with lower aspect ratio drilling, compared to classical gradient-index lenses. The lens is designed to operate in the 140-170 GHz bandwidth, and a prototype with height of only 2.2 mm and diameter of 6.6 mm was fabricated and characterize. The prototype is small enough to fit in many integrated circuit packages. The flat lens was compared to a non-flat core lens in terms of pattern quality, return loss and dielectric loss, with only negligible performance degradation.
Conference paper
(2024)
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Nick van Rooijen, M. Spirito, A. Bechrakis Triantafyllos, N. Llombart, M. Alonso-delPino
This contribution presents the measurement strategy to accurately characterize probe-fed high-gain antennas operating in the sub-THz band. First, a near-field technique employing a quasi-optical system is introduced to enable characterization of backside radiating antennas (with respect to the landing pads). The proposed setup employs classical manipulators for probe landing (i.e., above the structure) and linear xyz CNC controlled translation stage. After, the calibration and modelling techniques to allow for an accurate input reflection-coefficient at the antenna input plane, and the estimation of the antenna gain, in a near field planar scanning system, are described in details. The experimental data of an high-gain backside-radiating lens antenna operating in D-band are presented to validate the proposed approach and characterization bench.
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This contribution presents the measurement strategy to accurately characterize probe-fed high-gain antennas operating in the sub-THz band. First, a near-field technique employing a quasi-optical system is introduced to enable characterization of backside radiating antennas (with respect to the landing pads). The proposed setup employs classical manipulators for probe landing (i.e., above the structure) and linear xyz CNC controlled translation stage. After, the calibration and modelling techniques to allow for an accurate input reflection-coefficient at the antenna input plane, and the estimation of the antenna gain, in a near field planar scanning system, are described in details. The experimental data of an high-gain backside-radiating lens antenna operating in D-band are presented to validate the proposed approach and characterization bench.
Conference paper
(2023)
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Nick van Rooijen, Maria Alonso-delPino, Juan Bueno, Marco Spirito, Nuria Llombart
This contribution presents the development of an electrically small lens antenna using an artificially loaded thermoplastic at 140-170GHz. We will present the on-going development of the Fly’s Eye front end antenna concept that was presented in [1]. The antenna is composed on a dual plastic lens, a core lens and a shell lens, fed by a double slot. The core-lens, being presented in this contribution, is a spherical lens made from an artificially loaded plastic of permittivity 9.5. To the best of our knowledge, this thermoplastic material has not been used for lens antennas in this frequency range before. A 4mm lens prototype has been developed using this material, which includes an antireflective layer synthesized by drilling sub-wavelength holes on the lens contour. Full-wave simulations show a negligible degradation of the performance of the anti-reflection layer compared to an ideal homogeneous matching layer. Physical measurements and antenna measurements confirm that the antenna's performance matches the design specifications.
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This contribution presents the development of an electrically small lens antenna using an artificially loaded thermoplastic at 140-170GHz. We will present the on-going development of the Fly’s Eye front end antenna concept that was presented in [1]. The antenna is composed on a dual plastic lens, a core lens and a shell lens, fed by a double slot. The core-lens, being presented in this contribution, is a spherical lens made from an artificially loaded plastic of permittivity 9.5. To the best of our knowledge, this thermoplastic material has not been used for lens antennas in this frequency range before. A 4mm lens prototype has been developed using this material, which includes an antireflective layer synthesized by drilling sub-wavelength holes on the lens contour. Full-wave simulations show a negligible degradation of the performance of the anti-reflection layer compared to an ideal homogeneous matching layer. Physical measurements and antenna measurements confirm that the antenna's performance matches the design specifications.
We present a resonant leaky-wave lens antenna, fed by a circular waveguide with annular corrugations in the ground plane. The proposed leaky-wave feed reduces the impact of the spurious TM0 leaky-wave mode in all planes over a wide bandwidth while reducing assembly complexity compared to previous methods. The proposed leaky-wave antenna has an aperture efficiency above 80%, a return loss below -15 dB, and a cross-polarization level below -20 dB over a bandwidth from 110-220 GHz (2:1). We have fabricated and measured a WR-5 band (140-220 GHz) antenna prototype with a lens diameter of 3 cm that achieves excellent agreement between measurement and simulation in terms of return loss, directivity, and gain.
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We present a resonant leaky-wave lens antenna, fed by a circular waveguide with annular corrugations in the ground plane. The proposed leaky-wave feed reduces the impact of the spurious TM0 leaky-wave mode in all planes over a wide bandwidth while reducing assembly complexity compared to previous methods. The proposed leaky-wave antenna has an aperture efficiency above 80%, a return loss below -15 dB, and a cross-polarization level below -20 dB over a bandwidth from 110-220 GHz (2:1). We have fabricated and measured a WR-5 band (140-220 GHz) antenna prototype with a lens diameter of 3 cm that achieves excellent agreement between measurement and simulation in terms of return loss, directivity, and gain.
This work presents a novel lens antenna architecture based on a core-shell lens design with a leaky-wave in-packaged antenna at 150GHz. An electrically small core lens made of dense dielectric material is used to enhance the radiation of the in-packaged antenna. A low-loss dielectric shell lens with electrically large dimensions is then added to provide high directivity. A microstrip feeding network for connection to a 150GHz chipset is then also discussed. The proposed lens antenna provides good quality patterns with aperture efficiencies above 80% over a bandwidth of 20%.
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This work presents a novel lens antenna architecture based on a core-shell lens design with a leaky-wave in-packaged antenna at 150GHz. An electrically small core lens made of dense dielectric material is used to enhance the radiation of the in-packaged antenna. A low-loss dielectric shell lens with electrically large dimensions is then added to provide high directivity. A microstrip feeding network for connection to a 150GHz chipset is then also discussed. The proposed lens antenna provides good quality patterns with aperture efficiencies above 80% over a bandwidth of 20%.
Conference paper
(2022)
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Sjoerd Bosma, Nick van Rooijen, Maria Alonso Del Pino, Marco Spirito, N. Llombart
We report the measured results of a sparse, 4x1 scanning lens phased array prototype at W-band that is capable of beam steering a directive (>30 dBi) beam towards ±20° with sidelobe levels around -10 dB. The array elements are high-aperture-efficiency resonant leaky-wave lens antennas with a feed that suppresses the spurious TM0 mode over a wide bandwidth by using a circular waveguide in a ground plane surrounded by annular corrugations. The scanning lens phased array relies on simultaneous electrical and mechanical phase shifting to steer the beams. We use 15 GHz IQ-mixers followed by x6 multipliers to achieve electronic amplitude and phase control at W-band and a piezo-electric motor for mechanical phase shifting, which allows us to scan this array up to 20°. Measurements at 90 GHz of the lens array are in excellent agreement with simulations. More measurement results will be presented at the conference.
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We report the measured results of a sparse, 4x1 scanning lens phased array prototype at W-band that is capable of beam steering a directive (>30 dBi) beam towards ±20° with sidelobe levels around -10 dB. The array elements are high-aperture-efficiency resonant leaky-wave lens antennas with a feed that suppresses the spurious TM0 mode over a wide bandwidth by using a circular waveguide in a ground plane surrounded by annular corrugations. The scanning lens phased array relies on simultaneous electrical and mechanical phase shifting to steer the beams. We use 15 GHz IQ-mixers followed by x6 multipliers to achieve electronic amplitude and phase control at W-band and a piezo-electric motor for mechanical phase shifting, which allows us to scan this array up to 20°. Measurements at 90 GHz of the lens array are in excellent agreement with simulations. More measurement results will be presented at the conference.
Journal article
(2022)
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Sjoerd Bosma, Nick van Rooijen, Maria Alonso Del Pino, Marco Spirito, Nuria Llombart
We report on the first demonstration of dynamic beam steering using a scanning lens phased array. A scanning lens phased array relies on a combination of mechanical and electrical phase shifting to dynamically steer a high-gain beam beyond the grating-lobe free region using a sparse array. These two concepts have been demonstrated separately in the past, here we present, for the first time, a prototype demonstration where active mechanical and electrical phase shifting are combined. For this purpose, we have developed a sparse 4x1 scanning lens phased array at W-band (75-110 GHz) capable of beam steering a directive beam (>30 dBi) towards ± 20° with low grating lobe levels (around -10 dB). The lens array is fed by a waveguide-based leaky-wave feeding architecture that illuminates the lenses with high aperture efficiency over a wide bandwidth, which is required in the proposed scanning lens phased array architecture. The electrical phase shifting has been implemented using IQ-mixers around 15 GHz in combination with x6 multipliers to reach the W-band. The mechanical phase shifting relies on a piezo-electric motor, which is able to achieve displacements of the lens array of 6 mm with an accuracy of a few nanometers. The entire active array is calibrated over the air with an ad-hoc quasi-optical measurement setup. Resulting measurements show excellent agreement with the anticipated performance.
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We report on the first demonstration of dynamic beam steering using a scanning lens phased array. A scanning lens phased array relies on a combination of mechanical and electrical phase shifting to dynamically steer a high-gain beam beyond the grating-lobe free region using a sparse array. These two concepts have been demonstrated separately in the past, here we present, for the first time, a prototype demonstration where active mechanical and electrical phase shifting are combined. For this purpose, we have developed a sparse 4x1 scanning lens phased array at W-band (75-110 GHz) capable of beam steering a directive beam (>30 dBi) towards ± 20° with low grating lobe levels (around -10 dB). The lens array is fed by a waveguide-based leaky-wave feeding architecture that illuminates the lenses with high aperture efficiency over a wide bandwidth, which is required in the proposed scanning lens phased array architecture. The electrical phase shifting has been implemented using IQ-mixers around 15 GHz in combination with x6 multipliers to reach the W-band. The mechanical phase shifting relies on a piezo-electric motor, which is able to achieve displacements of the lens array of 6 mm with an accuracy of a few nanometers. The entire active array is calibrated over the air with an ad-hoc quasi-optical measurement setup. Resulting measurements show excellent agreement with the anticipated performance.
In this contribution, we present a plastic resonant leaky-wave lens antenna with high aperture efficiency (>80%) over a 1:2 bandwidth centered at 180 GHz. This antenna can be integrated in a scanning lens phased array architecture for next-generation wireless and sensing applications that require high-directivity steerable beams. The high aperture efficiency is achieved thanks to the combination of annular corrugations in the ground plane with a leaky-wave resonant cavity. A WR-5 (140-220 GHz) prototype is manufactured and measured in terms of reflection coefficient, radiation patterns, directivity, losses, cross-polarization and scan performance, showing excellent agreement with simulations.
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In this contribution, we present a plastic resonant leaky-wave lens antenna with high aperture efficiency (>80%) over a 1:2 bandwidth centered at 180 GHz. This antenna can be integrated in a scanning lens phased array architecture for next-generation wireless and sensing applications that require high-directivity steerable beams. The high aperture efficiency is achieved thanks to the combination of annular corrugations in the ground plane with a leaky-wave resonant cavity. A WR-5 (140-220 GHz) prototype is manufactured and measured in terms of reflection coefficient, radiation patterns, directivity, losses, cross-polarization and scan performance, showing excellent agreement with simulations.