| 1. |
- Aliakbari Abar, Hanieh, et al.
(author)
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Characteristic mode analysis of planar dipole antennas
- 2019
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In: 2019 13th European Conference on Antennas and Propagation (EuCAP). - 9788890701887 - 9781538681275
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Conference paper (peer-reviewed)abstract
- Planar monopole antennas are popular due to their attractive properties, but their operating mechanisms are still not well understood. Based on image theory, planar monopoles can be analyzed using their dipole counterparts. Here, the bandwidth and radiation pattern of planar dipoles is studied in detail using characteristic mode analysis for different design parameters. The results show that insignificant modes can help to improve the bandwidth without contributing to the radiation property. Moreover, a tradeoff is observed between pattern stability and impedance bandwidth as the dipole width varies. Furthermore, it is found that an offset in the feed point leads to a degradation in both the modal and impedance bandwidths.
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| 2. |
- Bencivenni, Carlo, et al.
(author)
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5G mmWave Beam Steering Antenna Development and Testing
- 2019
-
In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - 9788890701887
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Conference paper (peer-reviewed)abstract
- mmWave frequencies offer unprecedented capacity but also new technical challenges. Current solutions typically adopt integrated PCB antennas, however they still face issues when it comes to coverage, power consumption and cost. Instead, we present a SG mmWave antenna platform demonstrating a different approach based on Gapwaves technology. The proposed design is an integrated all-metal multi-layer assembly, offering low-loss feeding, high-gain subarray, high-Q filters and exceptional thermal handling. To support these claims, active measurement of beam steering, EIRP and temperature are presented. Results from this small demonstration unit are very encouraging and show performance challenging that of much larger systems.
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| 3. |
- Björkqvist, Oskar, et al.
(author)
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Additive Manufactured Three Dimensional Luneburg Lens for Satellite Communications
- 2019
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In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788890701887
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Conference paper (peer-reviewed)abstract
- A method for designing gradient refractive index (GRIN) lenses with additive manufacturing or 3D-printing at K-u band is presented. To demonstrate the potential of the method, we designed a Luneburg lens using a single low-loss dielectric material available for 3D-printers. The gradient index is realized by varying the local material fill density of the lens. We demonstrate with full wave simulations that the structure is able to transform a spherical electromagnetic wave to a plane wave. When the lens is fed with a rectangular waveguide, the overall antenna has a gain of 23 dBi with side lobe levels of -12.5 dB in K-u band. This lens, when integrated with a circular polarized feeding system, could find application for ground satellite communications.
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| 4. |
- Brazalez, Astrid Algaba, et al.
(author)
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Implementation of a compact Ka-band parallel plate Luneburg lens based on a hybrid dielectric/metasurface unit cell
- 2019
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In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - : IEEE. - 9788890701887
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Conference paper (peer-reviewed)abstract
- The complete implementation and numerical validation of a compact cost-effective multiport parallel plate Luneburg lens antenna operating at 28 GHz is described in this paper. The lens design consists of two parallel plates separated by a gap where each of them contains a metasurface structure based on a new type of combined dielectric/holey unit cell periodically arranged in a glide-symmetric configuration. The required refractive index is achieved by a combination of coarse control by adding a dielectric in the gap, and fine tuning by changing the height of the holes. The simulations of the final prototype including a flare to ensure a smooth wave transition from the parallel plate configuration to air, as well as a coaxial-to-waveguide-to-parallel plate feeding, show a 20% bandwidth for 11.5 dB return loss, and the crosstalk remains below -15 dB for the same frequency band.
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| 5. |
- Dahlberg, Oskar, et al.
(author)
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Low-Dispersive Glide-Symmetric Leaky-Wave Antenna at 60 GHz
- 2019
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In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - : IEEE. - 9788890701887
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Conference paper (peer-reviewed)abstract
- In this work we demonstrate a method for producing low-loss, non-squinting, directive leaky-wave antennas (LWAs) for millimeter-wave frequencies. The scanning behaviour of the radiation pattern arises from the dispersive nature of the waveguide mode, which is leaking out when opening the wave guiding structure. We propose a method to cancel the dispersive behaviour, by allowing the leaked waves to refract in a dispersive prism-lens. The proposed method allows for fully metallic implementation of the antenna, resulting in low losses. Furthermore, high directivity is easily achieved with a simple feeding. The corresponding theory is outlined, and the proposed method is used to design an antenna operating at 60 GHz. The obtained bandwidth, with less than 1 degrees beam scanning, is 20% in simulations and the realized gain of the antenna is 17 dB across the entire bandwidth. The design is proposed as an alternative to obtain high gain antennas for 5G applications, in which low losses and narrow beams are expected to be key features for mm-waves.
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| 6. |
- Ebrahimizadeh, Javad, et al.
(author)
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Electromagnetic Time-Reversal Technique for Monitoring Skull Healing Stages
- 2019
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In: 2019 13th European Conference On Antennas And Propagation (EuCAP). - : IEEE. - 9788890701887
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Conference paper (peer-reviewed)abstract
- This paper provides a novel non-resonant spectroscopy technique for monitoring of the healing process in skull defects created in cranial surgery. Currently, there is not such a method and information on the healing process which is vital to avoid further complications and for a better understanding of the process. During the healing, which can take several months, the thickness and the permittivity of the skull varies. The proposed approach makes use of the approximated Dyadic Green's function integral equation for deriving the variations in permittivity of the skull. The scattered electric field from the defect is collected using Time-Reversal Array (TRA) in order to produce the Multi-StaticData Matrix (MDM). The singular value decomposition on the MDM matrix based on time reversal operator (TRO) decomposition (known under French acronym DORT), provides information of the permittivity of the defect. The problem of the sensing the defect response after the cranial surgery is formulated for multi-layer medium and it will be shown that the dominant singular values are corresponding to the permittivity of the defect. Finally, the veracity of the theory is clarified by conducting a numerical simulation for a planar multi-layer medium consisting of skin, skull brain and a defect embedded in the skull. We show that the dominant singular values corresponding to the defect permittivity vary significantly which conclude that the dominant singular value can be a good criterion for monitoring the skull healing stages.
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| 7. |
- Eskandari, Hossein, et al.
(author)
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Design of Nonmagnetic All-mode Waveguide Coupler with Perfect Transmission Using Transformation Optics
- 2019
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In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788890701887
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Conference paper (peer-reviewed)abstract
- Using the transformation optics method together with the basic properties of Maxwell equations, a compact nonmagnetic waveguide coupler is designed that can ideally couple all TMn modes. Two compression functions are proposed to provide a perfect smooth transition between the waveguides. This coupler can be used to guide and compress a vacuumfilled waveguide to a smaller waveguide with a predefined higher dielectric constant inside. The design method is validated by simulated examples using COMSOL Multiphysics.
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| 8. |
- Fonseca, Nelson J. G., et al.
(author)
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The Water Drop Lens : a Low-Profile Geodesic Parallel Plate Waveguide Lens Antenna for Space Applications
- 2019
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In: 13th European Conference on Antennas and Propagation, EuCAP 2019. - : Institute of Electrical and Electronics Engineers (IEEE). - 9788890701887
-
Conference paper (peer-reviewed)abstract
- This paper introduces the design of a parallel plate waveguide geodesic lens modulated with spline functions. This geodesic lens design is rotational-symmetric, which naturally provides a high pattern stability over a wide angular range. The proposed design is thoroughly compared to the reference Rinehart-Luneburg lens and numerical results indicate similar electromagnetic performance, including scattering parameters and radiation, while enabling a height reduction by a factor of 2.6. This beamformer provides very wide angular scanning up to +/- 70 degrees with scan losses below 3 dB. The lens can be designed to provide very high aperture efficiency (between 80 and 90%) over a wide frequency operating range. Analyses were performed over the frequency range 26-32 GHz, demonstrating very stable performance. The very smooth shape of the lens is particularly attractive for applications at millimeter and sub-millimeter wavelengths.
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| 9. |
- Ghasemifard, Fatemeh, et al.
(author)
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Mimicking Twist Symmetry Properties in Flat Structures
- 2019
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In: 13th European Conference on Antennas andPropagation (EUCAP). - : Institute of Electrical and Electronics Engineers (IEEE). - 9788890701887
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Conference paper (peer-reviewed)abstract
- Twist symmetry provides an additional degree of freedom to control the wave propagation in periodic structures. However, real twist-symmetric structures are cylindrical structures that have a high cost of manufacturing. In addition, they are not compatible with the available, low-cost and flat technologies, such as microstrip technology. Here, we investigate the possibility of mimicking the dispersion properties of twist symmetry in flat structures.
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| 10. |
- Glazunov, Andres Alayon, 1969
(author)
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Far-field Reference Distance Criteria for Compact OTA Testing Ranges
- 2019
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In: 2019 13TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP). - 2164-3342. - 9788890701887
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Conference paper (peer-reviewed)abstract
- Analyzed are three criteria for the computation of a reference distance marking the start of the far-field region in antenna measurements. The analysis is based on a correction factor for the Friis formula at boresight in the Fresnel zone. Closed form equations are obtained as a function of frequency, the gains of the transmit and receive antennas and a user-defined accuracy factor. Based on the above a far-field reference distance similar to the Fraunhofer distance criterium is defined. The presented results will be essential to design cost-efficient characterization of wireless devices of any size with user-defined accuracy.
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