High Gain Pattern Research Articles

A High-Gain Pattern and Beamwidth Reconfigurable Dielectric Resonator Antenna based on Parasitic Metal Panels

A High-Gain Pattern and Beamwidth Reconfigurable Dielectric Resonator Antenna based on Parasitic Metal Panels

Prenatal Weight Change Trajectories and Perinatal Outcomes among Twin Gestations.

Despite an increase in twin pregnancies in recent decades, the Institute of Medicine twin weight gain recommendations remain provisional and provide no guidance for the pattern or timing of weight change. We sought to characterize gestational weight change trajectory patterns and examine associations with birth outcomes in a cohort of twin pregnancies. Prenatal and delivery records were examined for 320 twin pregnancies from a maternal-fetal medicine practice in Austin, TX 2011-2019. Prenatal weights for those with >1 measured weight in the first trimester and ≥3 prenatal weights were included in analyses. Trajectories were estimated to 32 weeks (mean delivery: 33.7 ± 3.3 weeks) using flexible latent class mixed models with low-rank thin-plate splines. Associations between trajectory classes and infant outcomes were analyzed using multivariable Poisson or linear regression. Weight change from prepregnancy to delivery was 15.4 ± 6.3 kg for people with an underweight body mass index, 15.4 ± 5.8 kg for healthy weight, 14.7 ± 6.9 kg for overweight, and 12.5 ± 6.4 kg for obesity. Three trajectory classes were identified: low (Class 1), moderate (Class 2), or high gain (Class 3). Class 1 (24.7%) maintained weight for 15 weeks and then gained an estimated 6.6 kg at 32 weeks. Class 2 (60.9%) exhibited steady gain with 13.5 kg predicted total gain, and Class 3 (14.4%) showed rapid gain across pregnancy with 21.3 kg predicted gain. Compared to Class 1, Class 3 was associated with higher birth weight z-score (β = 0.63, 95% confidence interval [CI]: 0.31,0.96), increased risk for large for gestational age (IRR = 5.60, 95% CI: 1.59, 19.67), and birth <32 weeks (IRR = 2.44, 95% CI: 1.10, 5.4) that was attenuated in sensitivity analyses. Class 2 was associated with moderately elevated birth weight z-score (β = 0.24, 95% CI: 0.00, 0.48, p = 0.050). Gestational weight change followed a low, moderate, or high trajectory; both moderate and high gain patterns were associated with increased infant size outcomes. Optimal patterns of weight change that balance risk during the prenatal, perinatal, and neonatal periods require further investigation, particularly in high-risk twin pregnancies. · A majority gained weight below IOM twin recommendations.. · Three patterns of GWC across pregnancy were identified.. · Moderate or high GWC was associated with infant size..

An efficient antenna system with improved radiation for multi-standard/multi-mode 5G cellular communications

This paper introduces a multi-input multiple-output (MIMO) antenna array system that provides improved radiation diversity for multi-standard/multi-mode 5G communications. The introduced MIMO design contains four pairs of miniaturized self-complementary antennas (SCAs) fed by pairs of independently coupled structures which are symmetrically located at the edge corners of the smartphone mainboard with an overall size of 75 × 150 (mm2). Hence, in total, the design incorporates four pairs of horizontally and vertically polarized resonators. The elements have compact profiles and resonate at 3.6 GHz, the main candidate bands of the sub-6 GHz 5G spectrum. In addition, despite the absence of decoupling structures, adjacent elements demonstrate high isolation. To the best of the authors’ knowledge, it is the first type of smartphone antenna design using dual-polarized self-complementary antennas that could possess anti-interference and diversity properties. In addition to exhibiting desirable radiation coverage, the presented smartphone antenna also supports dual polarizations on different sides of the printed circuit board (PCB). It also exhibits good isolation, high-gain patterns, improved radiation coverage, low ECC/TARC, and sufficient channel capacity. The introduced antenna design was manufactured on a standard smartphone board and its main characteristics were experimentally measured. Simulations and measurement results are generally in good agreement with each other. Moreover, the presented antenna system delivers low SAR with adequate efficiency when it comes to the appearance of the user. Hence, the design could be adapted to 5G hand-portable devices. As an additional feature, a new ultra-compact phased array millimeter-wave antenna with super-wide bandwidth and end-fire radiation is being introduced for integration into the MIMO antenna systems. As a result, the proposed antenna system design with improved radiation and multi-standard operation is a good candidate for future multi-mode 5G cellular applications.

Four-Element/Eight-Port MIMO Antenna System With Diversity and Desirable Radiation for Sub 6 GHz Modern 5G Smartphones

In this manuscript, a multiple-input multiple-output (MIMO) antenna array system with identical compact antenna elements providing wide radiation and diversity function is introduced for sub 6 GHz fifth-generation (5G) cellular applications. The introduced design contains four pairs of miniaturized square-loop resonators with dual-polarization and independently coupled T-shaped feed lines which have been placed symmetrically at the edge corners of the smartphone mainboard with an overall size of 75 mm × 150 mm. Therefore, in total, the introduced array design encompasses four pairs of horizontally and vertically polarized resonators. The elements are very compact and utilize at 3.6 GHz, a potential 5G candidate band. In order to improve the frequency bandwidth and radiation coverage, a square slot has been placed and excited under each loop resonator. Desirable isolation has been observed for the adjacent elements without any decoupling structures. Therefore, they can be considered self-isolated elements. The presented smartphone antenna not only exhibits desirable radiation but also supports different polarizations at various sides of the printed circuit board (PCB). It exhibits good bandwidth of 400 MHz (3.4-3.8 GHz), high-gain patterns, improved radiation coverage, and low ECC/TARC (better than 0.004 and -30 dB at 3.6 GHz, respectively). Experimental measurements were conducted on an array manufactured on a standard smartphone board. The simulated properties of this MIMO array are compared with the measurements, and it is found that they are in good agreement. Furthermore, the introduced smartphone array offers adequate efficiency in both the user interface and components integrated into the device. As a result, it could be suitable for 5G handheld devices.

Gain enhancement of co-planar waveguide fed ultra-wide bandwidth monopole antenna with enlarged ground plane and metal reflectors

This study investigates the capability of an omnidirectional monopole antenna in achieving a high gain pattern that can be used in the UWB applications covering the frequency range of 3.1–10.6 GHz. The gain of a co-planar fed reference antenna with a partial ground is enhanced by using two main techniques; incorporating the antenna with an enlarged ground plane and metal reflector plates in different configurations. The gain level of the reference antenna in the yz-plane (1.9–4.6 dBi) is enhanced up to a gain level of 9.25–14.8 dBi with the help of the two gain enhancement techniques. Furthermore, a minimum gain of 12 dBi with a maximum deviation of 3 dBi is observed over the 4.2–9.8 GHz frequency range. As a proof of concept, two configurations of the designed antennas are fabricated and tested.

A high gain pattern stabilized array antenna fed by modified Butler matrix for 5G applications

In this work, a beam-steering array antenna with the aim of pattern stabilization is presented. The antenna element consists of three-layer and a unique structure of the metalized via hole. It is capable to cover the frequency range from 20.5 to 30 GHz and a stable pattern over thorough operation frequencies. Moreover, the element has a constant gain with the peak of 9.5dBi. Additionally, the proposed modified Butler matrix consists of two 90-degree and two 135-degree couplers without phase shifting section to attain a pattern stabilized beam-steering array antenna. The proposed Butler matrix manages patterns in a constant phase over a frequency from 21 to 29 GHz with the phase error less than ±6°. The integration proposed element and feed network lead to a beam-tilting array antenna which can manage its patterns via input ports and maintain direction by frequencies variation range between 21.1 and 28.8 GHz.

Wide-Angle Scanning Phased Array Antenna using High Gain Pattern Reconfigurable Antenna Elements

This paper presents a wide-angle scanning phased array antenna using high gain pattern reconfigurable antenna (PRA) elements. Using PRA elements is an attractive solution for wide-angle scanning phased array antennas because the scanning range can be divided into several subspaces. To achieve the desired scanning performance, some characteristics of the PRA element such as the number of switching modes, tilt angle, and maximum half-power beamwidth (HPBW) are required. We analyzed the required characteristics of the PRA element according to the target scanning range and element spacing, and presented a PRA element design guideline for phased array antennas. In accordance with the guideline, the scanning range was set as ±70° and a high gain PRA element with three reconfigurable patterns was used to compose an 8x1 array antenna with 0.9 λ0 spacing. After analyzing whether the active element patterns meet the guideline, the array antenna was fabricated and measured to demonstrate the scanning performance. The fabricated array can scan its beam from -70° to 70° by dividing the scanning range into three subspaces. It shows that even if the array antenna has large element spacing, the desired scanning performance can be obtained using the elements designed under the guideline.

Wide band yagi antenna for terahertz application with graphene control

Antennas are an important part in the microwave and THz systems for the enhancement of the radiation in various application such as medical imaging. Yagi antenna because of end fire radiation, wide bandwidth and high gain are attractive in THz detector, wireless communications and THz medical imaging. Therefore, in this article we have developed a Yagi antenna for 1THz applications with high gain and in this antenna a graphene loop is added to dipole radiator and with variation in the graphene biasing, reconfigurable characteristic is obtained and the Q-factor is controlled in antenna. The CST microwave studio is used for modeling and simulation with FDTD solution. The antenna’s total size is 0.53λ×0.73λ for 1THz with the 1μm thickness of the Silicon substrate. Finally, a novel model has been suggested for the implementation of graphene layer in PBG layer and by embedding a graphene pin in PBG layer a Fabry-Perot waveguide has been designed that improves the bandwidth and antenna gain simultaneously. Higher Q- factor, higher bandwidth with high gain pattern are the benefits of the novel structure that are important in THz systems.

High-Gain Pattern Reconfigurable MIMO Antenna Array for Wireless Handheld Terminals

The analysis, design, experimental development, and test results of a high-gain pattern reconfigurable antenna array are presented. Unlike traditional phased arrays, the proposed array has a compressed footprint making it suitable for handheld device applications. The array pattern is reconfigured at 0°, 70°, and 290° in the azimuth plane with the help of low loss RF switches while the utilization of a collinear geometry allows narrow elevation plane beamwidth and high peak gain (between 9.7 and 11 dBi using FR4 material). System level analysis shows about 59% increase in signal-to-interference-plus-noise ratio level compared to omnidirectional antennas.

In brief

PAGE 1633 InAsP/InP photonic crystal slab nanolasers with uniquely shaped alphabet letter-like near-field emission modes have been created in work from the US, Spain and France. The work demonstrates that photonic crystals have the capability to manipulate the propagation of light on the nanoscale in anomalous but controllable ways. PAGE 1630 Researchers in Japan report a technique for etching the overcladding layer of perfluorinated graded-index polymer optical fibre (PFGI-POF) using chloroform and water. This has allowed them to observe a clear Brillouin signal, important for developing Brillouin-based distributed strain/temperature sensors and flexible Brillouin devices including optical storage, phase conjugators and slow light generators. The slab nanolasers presented show photonic crystals’ capability to manipulate light propagation at nanoscale PAGE 1632 In research from China, monolithic integration of triple terahertz quantum cascade lasers into an array has yielded a peak power of 213 mW obtained at 10 K with a threshold current density of only 257 A/cm2. The highest operating temperature of the array laser is identical to that of the single ridge laser, indicating good heat dissipation design in the array. The etching technique for PFGI-POF has allowed observation of a clear Brillouin signal PAGE 1629 A novel p-n− -metal SiC photodiode structure with higher quantum efficiency in the deep UV spectrum than previously demonstrated by pin or n-Schottky diode SiC structures is presented in work from the US. The work is aimed at high sensitivity deep UV photodetectors for applications including chemical and biological identification, optical wireless communications, and UV sensing systems. Peak power of 213 mW was achieved with the monolithically integrated terahertz quantum cascade laser array PAGE 1593 Research from Ireland presents a gain enhanced planar Yagi-Uda antenna with pattern reconfiguration, implemented in a simpler way. The developed single element high-gain pattern reconfigurable antenna can be kept as a single element to enhance the performance of various already established basic array antenna models, and the technique can be used in various array configurations to enhance the gain and pattern reconfiguration together. Aimed at high sensitivity deep UV photodetectors the p-n− metal SiC photodiode structure has improved quantum efficiency The simpler implementation of a planer Yagi-Uda antenna is suitable for use in a variety of established array antenna models

Low Probability of Intercept Antenna Array Beamforming

A novel transmit array beamforming approach is introduced that offers low probability of intercept (LPI) for surveillance radar systems employing phased array antennas. Radar systems are often highly visible to intercept receivers due to the inherent two-way versus one-way propagation loss. In this paper, the traditional high-gain antenna beam scanned across a search region is replaced with a series of low-gain, spoiled beams. Keeping the transmit antenna gain low reduces the radar visibility, but the radar's antenna performance remains unchanged as the original high-gain beam can be formed by processing the set of spoiled beams. Large transient power density radiated in a traditional scan is replaced with low power density persistently radiated at the target throughout the scan time. The detection performance of the radar is not affected since the total energy on the target is the same. Derivation of the complex weights to synthesize the high-gain patterns from the low-gain basis patterns is presented for both one-way and two-way beam patterns.

94 GHz Dual-Reflector Antenna With Reflectarray Subreflector

The design, construction and measured performance is described of an offset parabolic reflector antenna which employs a reflectarray subreflector to tilt the focused beam from the boresight direction at 94 GHz. An analysis technique based on the method of moments (MoM) is used to design the dual-reflector antenna. Numerical simulations were employed to demonstrate that the high gain pattern of the antenna can be tilted to a predetermined angle by introducing a progressive phase shift across the aperture of the reflectarray. Experimental validation of the approach was made by constructing a 28 times 28 element patch reflectarray which was designed to deflect the beam 5deg from the boresight direction in the azimuth plane. The array was printed on a 115 mum thick metal backed quartz wafer and the radiation patterns of the dual reflector antenna were measured from 92.6-95.5 GHz. The experimental results are used to validate the analysis technique by comparing the radiation patterns and the reduction in the peak gain due to beam deflection from the boresight direction. Moreover the results demonstrate that this design concept can be developed further to create an electronically scanned dual reflector antenna by using a tunable reflectarray subreflector.

The coaxial beam-rotating antenna (COBRA): theory of operation and measured performance

Many microwave generators, especially high-power sources, utilize an azimuthally symmetric output mode such as the TM/sub 01/ circular waveguide or the coaxial TEM mode. If such a mode is projected into an antenna aperture and radiated directly, then a doughnut-shaped radiation pattern with a boresight null will result. Antenna designs to directly accommodate an azimuthally symmetric output mode and the high electric fields of high-power sources have been considered, but they tend to be low gain, do not radiate a boresight peak along the axis of the source, and the pattern peak direction changes with frequency. Mode conversion techniques to alter the aperture field distribution have also been explored, but losses and weight, size and cost additions impact negatively on total system design. This paper describes a novel antenna we call the coaxial beam-rotating antenna (COBRA) that mitigates many of the problems normally associated with the azimuthally symmetric output modes of high-power microwave sources. The COBRA accepts directly an azimuthally symmetric guided mode of a microwave source and radiates a high-gain pattern with a boresight peak. In addition, the COBRA operates with a wide bandwidth, is compatible with the intense electric fields associated with high-power microwave sources, and the geometry of the antenna can be easily configured to produce an arbitrarily (elliptically) polarized boresight field. This paper presents the fundamental theory of operation, derives pertinent design and performance equations, and gives the measured operating characteristics of a COBRA prototype.