Miracle-dz/UniFAR-FTUs huggingface dataset:
A Kirigami-Inspired Foldable Spherical Fully Dielectric Luneburg Lens Antenna

A kirigami-inspired foldable spherical fully dielectric Luneburg lens antenna using additive manufacturing technology is presented for the first time. The proposed lens is discretized into multilayer spherical shells which are subdivided by several interlaced annular dielectric sheets with different notch densities. The existence of the flexible notches and the different notch densities in different layers realize the structural foldability and the gradient distribution of the Luneburg lens, respectively. The foldable Luneburg lens in the unfolded state is fed by a horn antenna and the measured results reveal that the proposed antenna with different feed incidence angles has the reflection coefficients better than -10 dB in the entire Ku band, gains varying between 15.2 and 18.7 dBi, and symmetric radiation patterns with narrow beamwidths.
Novel Dual-Frequency Independent Beam-Scanning Reflectarray

This paper presents a novel reflectarray with independent beam scanning at dual frequencies. Loaded by a single p-i-n diode, two separate radiating structures in a unit cell are used to flexibly fulfill ideal reflection phases in two arbitrary bands. The fabricated X-band prototype shows that the measured 1-dB gain bandwidths at 9 GHz and 11.5 GHz are 31.1% and 26.1%, respectively, and the achieved scanning ranges are $\pm \mathbf{40}^{\circ}$ and $\pm \mathbf{50}^{\circ}$ within 3-dB gain variation.
A Spectral Projected Gradient-Newton Two Phase Method for Constrained Nonlinear Equations

In this paper, we proposed a spectral gradient-Newton two phase method for constrained semismooth equations. In the first stage, we use the spectral projected gradient to obtain the global convergence of the algorithm, and then use the final point in the first stage as a new initial point to turn to a projected semismooth asymptotically newton method for fast convergence.
A Shared Ground Economical Dielectric-Free Dual Polarized Antenna System for 5G Mobile Devices

A probe-fed dielectric-free antenna with wide impedance bandwidth is proposed in this paper. The conventional SMA (SubMiniature version A) connector could be used to realize this antenna. Here, the top plane is the radiating element with a modified cuboid. The ground plane is Copper with dimensions of 8mm $\mathrm{x}\ 8$ mm. This dielectric-free antenna offers an impedance bandwidth of 12.2%. As the form factor is minimal, the antenna could be panel mounted with modern 5G mobile devices. The same radiator is extended for dual-polarized system with shared ground.
ASSIMILATION OF WATER VAPOUR MOTION WINDS IN THE GLOBAL MODEL OF DWD

The impact of satellite winds derived from the water vapour channel in the global model of Deutscher Wetterdienst (DWD) was investigated in different seasons for a total of more than 50 days. The enhanced coverage offered by the additional data improves considerably the forecast in the Southern Hemisphere whilst in the Northern Hemisphere the impact varies with time and regions, being often positive over North America but in some cases negative over Europe. Further experiments using the new high density GOES winds gave positive results everywhere. It was decided to start the operational use of the water vapour and high density winds in spring 1998. To test the new operational configuration a system observation experiment was run withholding all satellite winds from the assimilation system. The forecast of the experiment were on average worse than routine as expected. Over Europe the impact was neutral but some cases of better forecast without satellite winds occurred and had to be investigated in more details.
A Diplexer-Based Dual-Slot LTE Antenna Design for Laptops with Metal Housing

Due to the compact form factor and widely used metal enclosures in state-of-the-art laptops, the design of LTE antennas, which require several broad operation bands, is rather challenging. In this paper, a dual-slot antenna, which is aimed to be placed on the corner of the laptop base, is proposed. In order to cover low and high LTE bands with a common feed, a diplexer integrated with matching networks is employed. The slots are placed at the joints between the metal base and the rim. The T-shaped slot comprises two shorted ends and an opening on the rim to provide two resonant modes. To meet the LTE operation needs, the two modes can be joined to form a broader matching band. Simulations and measurements are executed to demonstrate that the proposed design can suffice the WWAN antenna need on laptop platforms.
Performance of Cooperative SM-Aided Multiple Access Scheme with DF Relaying Protocol

Spatial modulation (SM) is a promising approach that has been introduced as an alternative to classical multiple-input multiple-output (MIMO) spatial multiplexing techniques with the hardware complexity reduction of those in mind, and is envisioned as a component in future 5G and beyond systems. Cooperative communications, on the other hand, provides additional diversity gains and high data rates while improving coverage. Combining the advantages of SM and cooperative communications would then further improve efficiency, without inducing a significant complexity. In this paper, a novel SM cooperative system with decode-and-forward (DF) protocol is proposed to ensure a viable balance between the system performance metrics: the transmission data rate and average bit error rate (BER). The system architecture and the corresponding signal processing with optimal detector (OD) for the cooperative SM system are presented in the presence of a direct communication link and multiple transmit/receive antennas at both the source (S), and the destination (D). Code division multiple access (CDMA) technique is also incorporated in the proposed solution to address multiple access contexts arising from very high data rate communications and involvement of multiple relays, respectively.
AMC-Loaded Millimeter-Wave CPW-Fed Monopole Antenna for 5G Wearable Applications

In this paper, a new millimeter-wave (mmWave) co-planar waveguide (CPW) fed monopole antenna backed by artificial magnetic conductor (AMC) is presented. A novel AMC unit cell has been designed and a 2×2 array is used below the antenna to increase the gain and achieve low specific absorption rate (SAR) values below 1.6 W/Kg. Novelty of AMC unit cell lies in the fact that single or dual band operation of the unit cell can be achieved by only adjusting the inner patch size without changing the outer dimensions of the unit cell. Presented AMC unit cell has zero reflection phase at 28GHz for single band operation. Proposed design has been designed using semi-flexible substrate making it suitable for 5G mmWave wearable applications.
Role of radiotherapy in the management of heterotopic ossification

Heterotopic ossification (HO) is a process of pathological bone formation in non-osseous tissue. Frequently, it is a complication that occurs from various causes such as traumatic, neurogenic, or genetic disorders, where trauma is the most common cause. HO is of major concern as it can lead to functional disorders, pain, and even to joint ankylosis. Non-steroidal anti-inflammatory drugs and radiotherapy (RT) are preferred in the treatment of HO. RT serves as an important modality for the management of HO because RT potentially inhibits osteoprogenitor cell proliferation. This is a case report of an 18-year-old girl, who developed grade 4 HO at her right hip joint following a fall from height. She, then, underwent excision of heterotopic bone and RT to the right hip joint at a dose of 8 gray (Gy) delivered in 1 fraction, within 48 h of excision. The patient did not report any acute adverse effects related to RT and demonstrated clinical improvement in her range of motion without any recurrence of HO at her 3 and 6-month follow-ups.
Beam-Squint Mitigated Transverse-Slot Leaky-Wave Antenna for Wideband Wireless Communications

Leaky-wave antennas (LWAs) have received increasing attentions in the recent decades. Generally, LWAs exhibit frequency dispersion, which would lead to narrow bandwidth for wireless communications. To mitigate this effect, this paper provides an innovative method of creating a non-positive slope in the dispersion diagram. It is attained by introducing square bracket-shaped metal pieces above a transverse-slot LWA. The finalized antenna achieves wideband fixed beams at $\theta=37^{\circ}\pm 2^{\circ}$ in the band from 9.5 to 12.2 GHz. A low-cost additive manufacturing technology is used for antenna fabrication. The measured performance of the fabricated prototype agrees with the simulated one.
Path Loss Analysis for Array Antenna systems in Underground Mine at 3.5GHz

In this paper, path loss characteristics of the underground mine channel for a 64-element uniform rectangular array (URA) antenna system at 3.5GHz are presented and analyzed. Measurements were conducted in an underground mine environment, including both line-of-sight (LoS) and best-line-of-sight (Best-LOS) scenarios, with the transmitter-receiver (Tx-Rx) separation distance ranging from 5m to 70m. The log-distance path loss model was used to evaluate the path loss performance from the measurement data. The obtained path loss exponents were found to be 1.56 and 1.76, with shadow fading standard deviation of 1.34dB and 2.32dB for LoS and Best-LOS, respectively. These results indicate that the propagation characteristics in an underground mine have a waveguide effect on the propagated signal. As a result, the 3.5 GHz frequency band could be a suitable candidate for 5G communications in underground mine environments.
An Anomalous Refraction Metagrating for Normal to Oblique Mode Conversion Into a Dielectric Medium

In this paper we present a metasurface that is able to convert a normally incident wave from free space into an obliquely propagating wave inside a dielectric with high efficiency. The metagrating is simulated as four layers of periodic wire gratings on a dielectric substrate and is able to convert a normally incident wave at 18.9 GHz to symmetric oblique modes propagating in the $\pm 65.4^{\circ}$ directions inside the dielectric with transmission coefficients of $2.9 \text{dB}$ and $-3.7\text{dB}$. All other propagating modes at this frequency, including the specular reflection and normal transmission modes, have a magnitude less than $-15\mathbf{dB}$.
Enhancement of Direction-of-Arrival Estimation Accuracy with Using Antenna Arrays Composed of Diverse Elements

An antenna array composed of diverse elements that can improve direction-of-arrival (DoA) estimation accuracy is presented in this paper. As many surveillance and radio-frequency positioning systems relay on measuring DoAs, improving the DoA accuracy is of great importance. However, due to the limited array dimension, the DoA accuracy of the arrays composed of identical elements is fundamentally difficult to improve. Besides, given the limited number of elements, arbitrarily increasing the array dimension can cause ambiguity. To alleviate these issues, we employ antennas with diverse shapes of radiation patterns to improve the DoA estimation accuracy. We compared the DoA estimation accuracy of a uniform linear array of three rectangular patch antennas and that of the same array of two rectangular patch antennas and one low-profile antenna with a monopole-like radiation pattern. Theoretical and Monte Carlo simulation results demonstrate that the DoA estimation error of the array composed of diverse antennas can reduce by up to 30% over a wide field of view.
Influence of climatic drivers and long term N fertilization on the production and leaching of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in a Norway spruce (Picea abies) forest stand

The influence of long-term nitrogen (N) fertilization and climatic drivers on the production and leaching of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) was studied in a Norway spruce (Picea abies (L.) Karst. ) forest stand. DOC and DON soil solution concentrations in the O horizon were roughly an order of magnitude larger than B horizon soil solution concentrations. Soil solution sampled in the O horizon did not seem to respond to N fertilization. In the B horizon, however, slightly elevated concentrations of DOC and DON were occasionally observed in the fertilized plots. There did not seem to be a substantial effect of N fertilization on soil solution concentrations of DOC and DON. A decisive influence of simple climatic drivers on the within-year dynamics of DOC and DON soil solution concentrations could not be determined in this work. The annual mean DOC concentrations were higher 2009 than 1995, which might reflect an influence of the tree stand development on DOC soil solution concentrations.
Recent Developments in mm-Wave Tomographic and Radar Imaging for Breast Cancer Detection

In this contribution, some of the main results of millimeter-wave imaging for breast cancer diagnosis using both radar and tomographic approaches are presented. In addition, the idea of using a dual-step approach for reconstructing the dielectric profile of the anomaly using the morphological information provided by the faster and computationally less expensive radar approach is presented.
A Novel Design Method of RIS Element with A Wideband Varactor-Tuned Example

Reconfigurable intelligent surfaces (RISs) are developing rapidly nowadays and considered as a key technology for next-generation communications. However, when designing RISs with wideband feature, the traditional design method is complex and time-costly because the trial-and-error simulations lack clear design guidance. Here, we propose a radiation method to model, design and evaluate a RIS element, where the design goal is to match the element impedance to a pre-calculated impedance determined by the diode parameters. Using the novel method, a varactor-tuned RIS element is designed with a wide bandwidth of 20%, and the average loss is about 1.1 dB at 5.4 GHz, which significantly improves the performance of RIS elements.
A Fast Indoor Coverage Prediction Scheme at 60 GHz Based on Image Processing, Geometrical Optics, and Transport Theory

3D ray tracing is used to accurately predict path loss, phase, and Received Signal Strength for various environments. In this paper, we develop a fast and approximate prediction scheme for indoor path loss using digital image processing, geometrical optics and transport theory. The proposed algorithm is tested in an apartment environment, and its performance is compared against a commercial 3D ray tracing software suite, Wireless InSite®.
Broadband Green's Function-Multiple Scattering Theory for Fast Band Solutions of Vector Electromagnetic Waves in 3D Perioidc Strutures

We extend the Broadband Green's function-Multiple Scattering Theory (BBGF-MST) approach to 3D problems of vector electromagnetic waves in periodic structures. A feature of BBGF is that the lattice Green's functions are broadband so that the coefficients of the vector spherical wave expansions are calculated rapidly for many frequencies. These are then used for speedy broadband calculations of the matrix elements of the KKR (Korringa-Kohn-Rostoker) eigenvalue equation. For the first two bands, the dimension of the KKR matrix equation is only 6 by 6. BBGF facilitates the calculations of the matrix elements for 5000 frequencies in 2.89 seconds. With this method, the band eigenvalues in vector 3D problems are computed in 2.89 second on a standard laptop for the first 2 bands. Results are illustrated and the lowest band solution has good agreement with that of the Maxwell-Garnett mixing formula at low frequency.
Quaternions in Signal and Image Processing: A comprehensive and objective overview

Quaternions are still largely misunderstood and often considered an “exotic” signal representation without much practical utility despite the fact that they have been around the signal and image processing community for more than 30 years now. The main aim of this article is to counter this misconception and to demystify the use of quaternion algebra for solving problems in signal and image processing. To this end, we propose a comprehensive and objective overview of the key aspects of quaternion representations, models, and methods and illustrate our journey through the literature with flagship applications. We conclude this work by an outlook on the remaining challenges and open problems in quaternion signal and image processing.
Ball Grid Array Integration of Wideband Planar Printed Array Apertures

This paper presents experimental results for a Planar Ultra-wideband Modular Antenna (PUMA) array integrated with a coaxial feed network using Ball Grid Array (BGA) technology. A PUMA aperture is designed and manufactured with a BGA interface in place of typical feed structures. The BGA-backed PUMA aperture is then connected to a matching BGA interface on a coaxial through test circuit, allowing typical embedded element RF characterization performance and functionality evaluation of the PUMA aperture as a BGA package.
Four Port CP-MIMO Antenna of Triangle Slots

A 2 x 2 multiple input multiple outputs (MIMO) circularly polarized CP-MIMO antenna is designed. An artificial magnetic conductor backs the slots to eliminate back radiation. Each slot is coupled to two orthogonal printed microstrip lines from a power divider that equally divides the power with a 90° phase difference for CP radiation. The proposed antenna provides 7.5 dBi peak gain and 12.7% axial ratio (AR) bandwidth with isolation better than -20 dB.
An Effective Beamforming Method for Microstrip Linear Arrays

Beamforming analysis using an effective MVDR algorithm has been investigated and presented for a microstrip linear array operating at 2.45GHz. MVDR algorithm is successfully developed and used to obtain peaks in the angular spectrum for the linear array antenna system. Prototypes for the antenna array have been built and tested with 16Tx/16Rx phased array platform. It is confirmed that the proposed MVDR algorithm provides the peaks accurately to form and steer the beam for the microstrip antenna array that is designed. All the simulation results are compared with measurement results and found to be in agreement.
A 33–101 GHz Ultra-Wideband Tightly Coupled Monopole Array (TCMA)

A new ultra-wideband tightly coupled monopole array (TCMA) is introduced. Namely, the unit-cell of our TCMA consists of a modified monopole element, which is capacitively coupled to two grounded vias. Notably, both the common-mode and loop-mode resonances are pushed out of the operating frequency band of our array, while the well-known broadside null found in the radiation pattern of traditional monopole antennas is entirely eliminated. In addition, to improve the scanning bandwidth of our array, a dielectric superstrate is accordingly utilized. The proposed antenna array is extremely low profile with a maximum thickness of $0.4\lambda_{H}$. Infinite array simulations of our antenna array demonstrate a bandwidth of 3:1 (33 GHz to 101 GHz) with VSWR<3 for a maximum scan-angle of ± 45° for all principal E-, H- and D-planes.
Optically Transparent Antenna on Glass Lens for AR Applications

We present an optically transparent antenna for Augment Reality (AR) smart glasses. It operates at 5GHz Wi-Fi band to maximize data rate transfer between Personal Computer (PC) / Mobile Phones to the AR glasses. The proposed antenna is made of sub-micron silver metallic mesh (Nanoweb), fabricated on a glass substrate with an optically clear adhesive and protection layer to avoid any damages to the antenna feature. The Nanoweb antenna has a 96% optically transparency with 4.4% haze that present minimal obstruction to the user's field of view, while enabling reliable Wi-Fi or sub-6 GHz 5G communications.
Design and Verification Methodologies of D-Band Antenna Modules for Security Imaging Applications

This research presents the design and verification methodologies of cavity-backed slot antenna (CBSA) modules for D-band security imaging applications. First, to realize low-loss feeding networks in the D-band spectrum, the microstrip transmission line (TL) and 3-D interconnection structures based on the multi-layer low-temperature co-fired ceramic (LTCC) process have been designed and characterized. Moreover, to achieve low-loss interconnection in local-oscillation (LO) & intermediate-frequency (IF) parts of transmitting (TX)/receiving (RX) modules, the transition structures between FR-4 PCB and LTCC have been realized by utilizing a flip-chip bonding process. Second, the CBSA with low-loss 3-D interconnection structures has been proposed for coupling mitigation between the indium phosphide (InP) chipset and antenna. Finally, the antenna modules have been integrated with InP TX/RX chipsets using bonding wires. The measured EIRP of the TX module and conversion gain of the RX module exhibit $3.3\sim 6.6\ \text{dBm}$ and $15.0\sim 25.5\ \text{dB}$ at $117\sim 145\ \text{GHz}$, respectively.
Phased Array Antennas with Wide-Angle Scanning: Design of Decoupling Feeding Network

This paper presents a new approach to address the challenge of achieving wide-angle impedance matching across the entire angle sweep in phased array antennas. This approach involves the design of a novel decoupling feed network structure that compensates for the changes in the active impedance of each antenna element during angle scanning. The proposed structure includes a loop with two different paths between the antenna feed, with one path taking a sample coupling from one antenna element and canceling out the over-the-air coupling effect on the other antenna. By properly designing the length of the path to be 180 degrees out of phase, the proposed approach achieves about 20 dB mutual coupling reduction at the center frequency. The decoupling network is applied to a 4 by 4 array antenna, and full-wave simulation results demonstrate its effectiveness. Compared to conventional wide-angle matching impedances, the proposed approach is adaptable to any linear array and does not require a real state on the aperture to operate.
Electro-Mechanically Tunable Low-Loss mm-Wave LP to LHCP or RHCP Conversion Metasurface

The design of a novel electro-mechanically tunable reflection polarization conversion metasurface at millimetre-wave frequencies is presented. Tunability is achieved via a variable air cavity between an anisotropic impedance surface and a ground plane. The air cavity height variation provides a polarization conversion from linear polarization to right-handed circular polarization or left-handed circular polarization. Simulations have been carried out using CST Microwave Studio to evaluate the proposed metasurface's reflection characteristics and tunability. Simulations demonstrate a controllable transition between the two circular polarization states at 76 GHz with extremely low reflection losses.
Morfología y composición de los nidos de vencejo común ("Apus apus") en Ávila (España)

Forty three common swift, Apus apus (Apus, Apodini, Apodinae, Apodidae), nests were collected from the medieval town walls of Avila (Spain) to provide new data on their structure and composition. Their adaptation to the cavity, and the type of nest determine the values of nest parameters. In turn, nest type is determined by the presence or lack of a base and a wall, which results in significant structural differences in total height, sidewall thickness, and edge length. Evidence was found that weight varies significantly between nest type depending on the content in leaves, fruit and seeds. Nesting material distribution within the structure of the nest varied according to the type of such material.