Gain Variation Research Articles

A multi-beam circularly polarised Fabry-Perot resonator antenna array using SIW for X-Band applications

ABSTRACT This paper presents a novel multi-layer beamforming antenna array based on Fabry-Perot resonator that is excited by a high-performance compact 4 × 4 Butler matrix using substrate integrated waveguide (SIW) technology for X-band application. The adapted ring patch antenna is fed through the aperture on a rectangular SIW cavity and forms the radiating element in the antenna array. Enhanced characteristics of the antenna array are realised by inserting an electromagnetic bandgap (EBG) structure between the radiating elements and a superstrate constituted from two complementary frequency selective surfaces (FSS) that forms a Fabry-Perot resonator (FPR). Circular polarisation in the proposed FPR SIW antenna array (FPRSAA) is achieved by using a combination of sequential phase rotation and orthogonal feeding techniques. Measured results of antenna array (Ant. II) show |S11| ≤ −10 dB between 8–12.0 GHz, a circular polarisation (CP) gain variation between 15.64–18.54 dBic, 3 dB axial-ratio between 8.5–11 GHz, and scanning angle covering −47 to 47 degrees.

Influence of the DASH Diet on Gestational Weight Gain and Perinatal Outcomes in Women with Pre-Existing Diabetes Mellitus: A Randomized, Single-Blind, Controlled Clinical Trial.

This study aimed to investigate the influence of the dietary approaches to stop hypertension (DASH) diet on gestational weight gain and perinatal outcomes in pregnant women with pre-existing diabetes mellitus (PDM). A randomized, single-blind, controlled clinical trial was conducted with 68 pregnant women with PDM throughout prenatal care until delivery (18 weeks) at a public maternity hospital in Rio de Janeiro, Brazil (2016-2020). The standard diet adopted by the control group (standard diet group-SDG) contained 45-55% carbohydrates, 15-20% protein, and 25-30% lipids of the total energy intake. An adapted DASH diet, with a similar macronutrient composition, but with higher calcium, potassium, magnesium, fiber, and reduced saturated fat, was prescribed for the intervention group (DASH diet group-DDG). Student's t- or Mann-Whitney U tests were used to compare outcomes between groups. To assess the trajectory of gestational weight gain throughout the intervention between the study groups, linear mixed-effects regression models were used. The DDG had lower gestational weight gain at the fifth (p = 0.03) and seventh appointment (p = 0.04), with no difference in average total gestational weight gain (SDG: 10 kg [SD = 4]; DDG: 9 kg [SD = 5], p = 0.23). There was a trend for a lower length of stay of the newborns (p = 0.08) in the DDG without differences for other perinatal outcomes. The DASH diet promoted less variation in gestational weight gain without promoting a difference in total gestational weight gain, and there was no difference between the study groups for perinatal outcomes.

A Multioutput and Highly Efficient GaN Distributed Power Amplifier for Compact Subarrays in Wideband Phased Array Antennas

This article presents the design, implementation, and measurement results of a multioutput distributed power amplifier (MODPA) in 100-nm AlN–GaN–AlGaN high-electron-mobility transistor (HEMT) on a silicon substrate. The proposed MODPA improves power-added efficiency (PAE) in distributed amplifiers (DAs) by not wasting reverse traveling waves and delivering all forward and reverse waves to the output ports. Utilizing MODPA in implementing a subarray-based phased-array transceiver reduces the number of power splitters and PAs, significantly reducing the subarray’s chip area and power loss. A design methodology for broadband, efficient amplifier implementation by optimizing load/source impedances at the fundamental and harmonic frequencies is presented based on comprehensive source/load—pull simulations and class-J dynamic load lines. The presented broadband design methodology addresses an ambiguity for picking optimum load/source impedance at a single frequency caused by higher order harmonics of operating frequencies dropping in the band. The fabricated MODPA occupies a 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 3 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> chip area. In 0.01–25-GHz frequency, MODPA delivered 37–41-dBm power to the four outputs, with a 17–21-dB total power gain and 22%–73% total PAE. The power gain and phase variation between the four matched-output ports are less than 1.5 dB and 3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> , respectively, making MODPA an attractive design for implementing subarrays.

A Low-Phase-Noise RF Up/Down-Converter for Cost-Effective 5G Millimeter-Wave Test Solutions

The increasing demand for millimeter-wave (mmWave) frequencies with wider signal bandwidths, such as 5G NR, requires large investments on test equipment. This work presents a 5G mmWave up/down-converter with a 40 GHz LO, fabricated in custom PCBs with off-the-shelf components. The mmWave converter has broad IF and RF bandwidths of 1∼5 GHz and 21∼45 GHz, and the built-in LO generates 20∼29.5 GHz and 33.5∼40 GHz of output. To achieve high linearity of the converter simultaneously, the LO must produce low-phase-noise and be capable of high harmonics/spur rejection, and design techniques related to these features are demonstrated. Additionally, a reconfigurable IF amplifier for bi-directional conversion is included and demonstrates low gain variation to maintain the linearity of the wideband modulation signals. The final designed converter is tested with 5G OFDM 64-QAM 100 MHz 1-CC (4-CC) signals and shows RF/IF output power of -3/8 dBm with a linear range of 35 (30)/38 (33) dB at an EVM of25 dB.

High‐gain high‐selectivity TE20‐mode SIW‐fed metasurface filtenna array for 5G millimeter‐wave applications

AbstractA high‐gain high‐selectivity 4 × 4 metasurface (MS) filtenna array is presented in this paper for 5G millimeter‐wave (mmW) applications. The TE20‐mode substrate integrated waveguide (SIW) with two parallel coupling slots is applied as the differential feeding structure, which can produce a wide impedance bandwidth and good radiation performances, simultaneously. Additionally, the TE20‐mode SIW feeding line is well designed to operate as a λ/2 short‐circuited line at the upper edge frequency to gain a radiation null. Meanwhile, a folded U‐shaped slot is etched on each MS unit to generate a radiation null at the lower edge. As a result, a passband which covers our 5G mmW band (24.25–29.5 GHz) of interest can be realized. To validate the design, a 4 × 4 MS filtenna array was manufactured and measured. The simulated and measured results are in good agreement, demonstrating a −10 dB impedance bandwidth of 19.8%, a flat gain variation with a maximum value of 19.82 dBi, symmetrical radiation patterns, low cross‐polarization levels of –30 dB, and high out‐of‐band rejection levels of 25 dB.

265 Manger Space Restriction Does not Negatively Impact Growth Efficiency of Feedlot Heifers Program fed a Concentrate-Based Diet to Gain 1.36 kg Daily

Abstract The objective of this research was to determine the influence manger space restriction had on program fed feedlot heifers during the growing phase. Charolais × Angus heifers [initial body weight (BW) = 329 ± 22.1 kg] were used in a 109-d backgrounding phase study. Heifers were received from a ranch in western South Dakota approximately 60 days before study initiation. Initial processing (53 days before study initiation) included individual BW measurement, application of a unique identification tag, vaccination against viral respiratory pathogens (Bovi-Shield Gold 5, Zoetis, Parsippany, NJ) and clostridial species (Ultrabac/Somubac 7, Zoetis), and administration of doramectin pour-on (Dectomax, Zoetis) for control of internal and external parasites. All heifers were administered 36 mg of zeranol (Ralgro, Merck Animal Health, Madison, NJ) at study initiation. Upon study initiation, heifers were assigned to 1 of 10 pens (n = 5 pens/treatment with 10 heifers/pen) in a randomized complete block design (blocked by location). Each pen was randomly assigned to 1 of 2 treatments: 20.3 cm (8IN) or 40.6 cm (16IN) of linear bunk space/heifer. Heifers were individually weighed on days 1, 14, 35, 63, 84 and 109. Heifers were programmed to gain 1.36 kg daily based on predictive equations for a medium frame steer calf set forth by the California Net Energy System. To calculate predictive values, a final BW of 575 kg was assumed to be the mature BW of the heifers and tabular net energy values of 2.05 NEm and 1.36 NEg from d 1 to 22, 2.00 NEm and 1.35 NEg from d 23 to 82, and 1.97 NEm and 1.32 NEg from d 83 to 109 were used, because of ingredient inventory changes. Data were analyzed using the GLIMMIX procedure of SAS 9.4 with manger space allocation as the fixed effect and block as the random effect. No differences (P &amp;gt; 0.35) were observed between 8IN or 16IN heifers for initial BW, final BW, average daily gain, dry matter intake, feed efficiency, variation in daily BW gain (within pen standard deviation) or applied energetic measures. No differences (P &amp;gt; 0.50) were observed between treatments for morbidity. Although not statistically analyzed, 8IN heifers appeared to have looser stools during the first two weeks compared with the 16IN heifers. These data suggest restricting manger space allocation from 40.6 cm to 20.3 cm did not negatively influence gain efficiency or the efficiency of dietary net energy utilization in heifers programmed fed a concentrate-based diet to gain 1.36 kg daily. The use of tabular net energy values and required net energy of maintenance and retained energy equations are an effective means to program cattle to a desired daily rate of gain during the growing phase.

High-Efficiency Circularly Polarized Phased Array Based on 5 μm-Thick Nematic Liquid Crystals: Design, Over-The-Air Calibration, and Experimental Validation

This paper presents a systematic investigation and demonstration of a K-band circularly polarized liquid-crystal-based phased array (LCPA), including the design, over-the-air (OTA) in-array calibration, and experimental validation. The LCPA contains 16 phase-shifting radiating channels, each consisting of a circularly polarized stacked patch antenna and a liquid-crystal-based phase shifter (LCPS) based on a loaded differential line structure. Thanks to its slow-wave properties, the LCPS exhibits a maximum phase-shifting range of more than 360° with a figure of merit of 78.3(° )·dB−1 based on a liquid crystal layer with a thickness of only 5 μm. Furthermore, an automatic OTA calibration based on a state ergodic method is proposed, which enables the extraction of the phase–voltage curve of every individual LCPA channel. The proposed LCPA is manufactured and characterized with a total profile of only 1.76 mm, experimentally demonstrating a scanned circularly polarized beam from −40° to +40° with a measured peak gain of 12.5 dBic and a scanning loss of less than 2.5 dB. The bandwidth of the LCPA, which satisfies the requirements of port reflection (|S11|) < −15 dB, an axial ratio (AR) < 3 dB, beam squinting < 3°, and a gain variation < 2.2 dB, spans from 25.5 to 26.0 GHz. The total efficiency is about 34%, which represents a new state of the art. The use of the demonstrated low-profile LCPA to support circularly polarized scanning beams, along with the systematic design and calibration methodology, holds potential promise for a variety of millimeter-wave applications.

A Hybrid Magnetic Current Sensor With a Multiplexed Ripple-Reduction Loop

This article presents a hybrid magnetic current sensor for galvanically isolated measurements. It consists of a CMOS chip that senses the magnetic field generated by current flowing through a lead-frame-based current rail. Hall plates and coils are used to sense low-frequency (dc to 10 kHz) and high-frequency (10 kHz to 5 MHz) magnetic fields, respectively. With the help of on-chip calibration coils, the biasing current of the Hall plates is trimmed to match the sensitivity of the Hall and coil signal paths. The sensitivity drift of the coil path with temperature is compensated by using temperature-dependent gain-setting resistors, while the drift of the Hall path is compensated by biasing the Hall plates with a proportional-to-absolute-temperature (PTAT) current. The resulting sensitivity drift is less than 9% from –40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C to 80 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> C. The offset of the Hall plates is reduced by the current spinning technique, and the resulting ripple is suppressed by a multiplexed ripple-reduction loop (MMRL). Fabricated in a standard 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$</tex-math> </inline-formula> m CMOS process, the current sensor occupies 4.6 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> and draws 7.8 mA from a 1.8-V supply. It achieves a gain variation of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 2% in a 5-MHz BW. It also achieves high energy efficiency, with an figure of merit (FoM) of 1.6 fW/Hz.

ADRC‐based control strategy for DC‐link voltage of flywheel energy storage system

AbstractThe direct current (DC)‐link voltage control of the flywheel energy storage system plays an important role in realizing high‐quality grid connection. With the traditional proportional‐integral control, the DC‐link voltage cannot track its reference value quickly and smoothly when the flywheel energy storage system switches from the charging stage to other working stages. Therefore, a DC‐link voltage control strategy for the flywheel energy storage system based on active disturbance rejection control is proposed in this paper to deal with this issue. The DC‐link voltage and its differential value are considered as the state variables in this strategy. The internal and external disturbances, such as load power, switching loss, and parameter uncertainty, are regarded as an expanded state. By inputting the voltage error and the observed disturbance into the nonlinear state feedback control law, the rapidity and anti‐interference of the DC‐link voltage control are ensured under different States of Charge of the flywheel energy storage system. Then, the coefficient freezing method is used to analyze the effects of the disturbance observation bandwidth by nonlinear gain and pole position changes. The DC‐link voltage can track the reference value over a wider frequency range of disturbances. By configuring the appropriate observer structure parameters, the disturbance observation bandwidth under the nonlinear function gain variation is always higher than the expected bandwidth. The effectiveness of the proposed control strategy is verified by simulation results at last.

Designing cladding mode interference device – a host for sensors and all-fiber inline gain-flattening component and broad-band filter

This article describes how to devise interference and self-imaging of core and cladding modes based devices using dissimilar core concatenated all-fibers. The core diameter mismatch in the structure excites the cladding modes with the core mode that leads to a progressive interference imaging between the cladding modes and the core mode yielding wavelength and refractive index dependent loss. Through a systematic study, we tune the device parameters to gauge temperature and concentration with sensitivity of 0.0713 dB/°C and 0.0372 dB/(% mL/mL) respectively as a high-performance fiber sensor. Next, optimizing the wavelength sensitive parameters of the host configuration, we investigate the transmission characteristics as gain-flattening filters (GFF) of Erbium-doped fiber amplifiers (EDFAs) with maximum gain variations of 0.91 and 0.97 dB, for two different EDFAs respectively over a wavelength band of 33 and 25 nm. Finally, we demonstrate a tunable and two-flattop band rejection filters with rejection band of 14, 26 and 46 nm, respectively.

A Simulation of Calibration and Map-making Errors of the Tianlai Cylinder Pathfinder Array

The Tianlai cylinder array is a pathfinder for developing and testing 21 cm intensity mapping techniques. In this paper, we use numerical simulation to assess how its measurement is affected by thermal noise and the errors in calibration and map-making process, and the error in the sky map reconstructed from a drift scan survey. Here we consider only the single frequency, unpolarized case. The beam is modeled by fitting to the electromagnetic simulation of the antenna, and the variations of the complex gains of the array elements are modeled by Gaussian processes. Mock visibility data are generated and run through our data processing pipeline. We find that the accuracy of the current calibration is limited primarily by the absolute calibration, where the error comes mainly from the approximation of a single dominating point source. We then studied the m-mode map-making with the help of Moore–Penrose inverse. We find that discarding modes with singular values smaller than a threshold could generate visible artifacts in the map. The impacts of the residue variation of the complex gain and thermal noise are also investigated. The thermal noise in the map varies with latitude, being minimum at the latitude passing through the zenith of the telescope. The angular power spectrum of the reconstructed map show that the current Tianlai cylinder pathfinder, which has a shorter maximum baseline length in the North–South direction, can measure modes up to l ≲ 2π b NS/λ ∼ 200 very well, but would lose a significant fraction of higher angular modes when noise is present. These results help us to identify the main limiting factors in our current array configuration and data analysis procedure, and suggest that the performance can be improved by reconfiguration of the array feed positions.

Design of a Wideband, High Steering Angle and Low Side-Lobes Levels Matrix Antenna

This paper presents the use of pixel-type radiating elements in the context of broadband beam steering. The elements are composed of a resonant cavity topped by a frequency selective surface, fed via a patch antenna and filled with dielectric substrates. This pixel antenna has a wide -10 dB matching band from 1.22 to 1.61 GHz, which corresponds to a 27% fractional bandwidth. It has an angular aperture greater than 124° and a realized gain between 3.3 and 3.8 dBi over the whole matching band. An array composed of 5 elements has been simulated and allows a steering on a range of ±60° in the E plane while keeping the gain variation below 3 dB. A prototype has been manufactured and presents a steering capacity between -56 and 53° on the whole band with side-lobes levels lower than -8.1 dB whatever the angle.

Low-Profile Ultra-Wideband Dual-Polarized Omnidirectional Antenna for Indoor Base Station

A low-profile ultra-wideband omnidirectional antenna with dual polarizations for indoor mobile communication is presented. The horizontally polarized (HP) omnidirectional element is introduced by using twelve I-shaped slot antennas, which are arranged in a circle-shaped array and excited by a 1-to-12 power divider. The vertically polarized (VP) omnidirectional performance is introduced by using a dual-M-shaped monopole with a small ground plane. To enhance the impedance matching within an ultra-wide bandwidth, a top metal disk with four chunks, a bottom metal loop and a ring slot embedded in the ground plane are employed for the design of the VP element. After replacing the metal disk of the VP element with the designed HP element, the omnidirectional antenna with dual polarizations is then simply achieved. By utilizing this new method, an ultra-wideband dual-polarized omnidirectional antenna for indoor mobile communications is designed, manufactured and measured. It has an ultra-wide bandwidth of 117% (1.44-5.5 GHz), a high isolation of 30 dB, and a low profile of 0.16λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> denotes the wavelength at the lowest frequency of the operating band). Good omnidirectional radiation performance with gain variation < 2.6 dBi is obtained for both HP and VP ports over the ultra-wide operating band.

A GaN MMIC Load-Modulated Balanced Amplifier With Modified Output Coupler for Efficiency Enhancement Over a Larger Power Back-Off Range

This brief firstly presents a monolithically microwave integrated circuit (MMIC) load-modulated balanced amplifier (LMBA) developed in 0.15um GaN process. In this brief, the asymmetric output coupler is applied for further enhancing output power and output back-off (OBO) efficiency over a larger OBO range. This MMIC LMBA operating mode is dependent on a three-ways active load modulation process by modified the coupling coefficient of output coupler which can provide more design parameters and freedom. To validate the proposed LMBA at millimeter wave (mm-wave), a 24.7-25.7 GHz MMIC LMBA is demonstrated, fabricated and tested. Measurements show that this MMIC LMBA can deliver a 35.2-dBm saturated output power with a peak drain efficiency of 37.7%. At 6-dB/8-dB/10-dB OBO, 23.8-30 %, 24.2-27 % and 20-24% power added efficiencies (PAE) can be obtained, respectively. The measured S21 is 15-dB with a 1 0.4-dB gain variation. When driven by a 100MHz 64-QAM OFDM modulation signal with a PAPR of 9.2-dB, the measured ACPR is improved to -45.04 dBc with DPD. In this case, the PA achieves an average efficiency of 25.2% and a 26.2-dBm average output power.

Simulation of the Effect of Interference and EIRP on the Qos of DVB-S2 and DVB-RCS2 Networks

The purpose of this study was to obtain the QoS value of the data sent from the user terminal to the gateway based on variations in antenna gain and to determine the effect of the level of interference caused by noise on the user's device on the quality of data reception. This research uses the NS3 software experimental method. Parameters analyzed include throughput, delay, PDR. This study uses quasi-experimental methods. The purpose of quasi-experimental research is pure experimental conditions in conditions where it is impossible to control or manipulate all relevant variables, namely estimating. The conclusion in this study has been successfully carried out simulating sending data packets using the NS3 simulator tools. Based on the simulations that have been carried out, several characteristics of the effect of antenna gain on the quality of data packet transmission are obtained. The simulations explain well that the values of throughput, delay, and PDR have increased so as to provide good service quality. Based on the simulations that have been carried out, several characteristics of the influence of the interference level that affect the user on the quality of sending data packets are obtained. The simulation explains well that the values of throughput, delay, and PDR experience stability so that the level of interference has no effect on users in sending packets. However, the values obtained are very good and have not decreased

Telemonitoring patients with chronic heart failure. Results from a pilot study in the Veneto Region, Italy

Remote monitoring of patients with chronic heart failure (HF) can prevent acute episodes of HF, optimize treatment, reduce emergency room (ER) visits and hospitalizations, and improve quality of life of patients and caregivers. In current clinical practice, however, the most appropriate model is still under debate. We aimed to evaluate the impact of a new remote telemonitoring (TM) system in the clinical management of HF patients on the reduction of hospitalizations and ER admissions and on possible related-economic benefits. A working group participated by primary care and family practitioners, cardiologists, home care nurses of the 8th Local Health Unit of the Veneto Region, Italy, has established a new operating procedure for TM chronic HF patients, identifying the clinical profiles and the inclusion/exclusion criteria of enrollment, the clinical parameters to be monitored, the input/output modalities of the information to/from the call center, the alarm criteria and the response procedures. Patients were profiled into three risk categories based on age, clinical characteristics, prognosis assessment, and social needs and provided with appropriate devices for remote measurement and transmission of blood pressure, heart rate, peripheral oxygen saturation (SpO2) and body weight. Clinical data, self-measured at home according to a predetermined schedule based on the patient's risk profile, were automatically transmitted to the operating center, generating, if above the threshold, a grading of alarms (green/cyan, yellow, red) and the consequent activation of the most appropriate response (returned phone calls to check patient's status, reporting to primary physician/family practitioner for clinical evaluation, notification to the HF outpatient clinic for an early follow-up visit, alerting medical emergency services). The number of hospitalizations and ER visits during the TM period was compared with the pre-TM equivalent for each individual patient. Overall, 22 patients with chronic HF were enrolled (mean age 82.3 ± 8.6 years, 17 males). The average duration of TM was 18.7 ± 8.8 months. Overall, 62 108 home measurements were performed and transmitted. The alarms received by the operating center were 4120 (6.6% of all measurements): 62% cyan, 30% yellow, 8% red. Most of the data above the threshold concerned weight gain (42.0%) and SpO2 variations (28.0%). During the observation period (TM period and pre-TM equivalent interval calculated for each individual patient), a total of 127 hospitalizations and 181 ED visits were recorded. Compared to the pre-TM period, there was a 66% reduction in hospitalizations for all causes (95 vs 32, p<0.001) and a 68% decrease in ED visits (137 vs 44, p<0.001). Similarly, hospitalizations and ED visits due to HF were reduced by 82% (p<0.001) and 66% (p<0.001), respectively, with a decrease in days of HF-related hospitalization from 211 to 48. Despite a higher cost for TM of € 6911.15, a total saving of € 64 103.87 was obtained for the reduction of expenses from € 8665.45 to € 2664.00 for ED visits and from € 71 627.93 to € 13 525.51 for HF hospitalizations. This pilot experience on remote monitoring HF patients proved to be effective in determining a significant reduction in ED visits and hospitalizations with a consequent significant economic benefit. Larger studies are needed to confirm this favorable outcome.

Half-mode substrate integrated waveguide based filtering leaky-wave antenna

In this communication, a filtering leaky wave antenna based on half-mode substrate integrated waveguide (HMSIW) is proposed. The band-pass filtering response is achieved using periodic radiating slots element on high- low impedance substrate integrated waveguide. Apart from flexible filtering, the proposed antenna also shows wide range beam scanning from backward to forward quadrant of 68° in the operating frequency range of 7.7 GHz to 10.9 GHz with low dielectric material with a size of 6.73 λo. The proposed antenna is having a maximum gain of 14 dBi with gain variation of 2 dB in the operating range. To achieve continuous forward and backward beam scanning, open-stopband mitigation is necessary which is also discussed along with flexible frequency filtering.

Microstrip Leaky-Wave Antenna With Circular Polarization and Broadside Radiation

In this letter, a novel circularly polarized microstrip leaky-wave antenna is proposed with broadside radiation and high gain. A conventional microstrip patch has been modified to obtain broadside gain along with circular polarization. The modified patch is periodically placed along one side of the 50 Ω delay line to form leaky-wave antenna. The optimized broadside frequency of the antenna is 10.1 GHz. The bandwidth associated with 3-dB axial ratio is 13.3% while the maximum obtained gain is 15.8 dBic. The measured gain variation within 3-dB axial ratio bandwidth is 1.6 dB. Measured results of the fabricated antenna follow the simulations.

The information on halo properties contained in spectroscopic observations of late-type galaxies

ABSTRACT Rotation curves are the key observational manifestation of the dark matter distribution around late-type galaxies. In a halo model context, the precision of constraints on halo parameters is a complex function of properties of the measurements as well as properties of the galaxy itself. Forthcoming surveys will resolve rotation curves to varying degrees of precision, or measure their integrated effect in the $\mathrm{H}\, \small {\rm I}$ linewidth. To ascertain the relative significance of the relevant quantities for constraining halo properties, we study the information on halo mass and concentration as quantified by the Kullback–Leibler divergence of the kinematics-informed posterior from the uninformative prior. We calculate this divergence as a function of the different types of spectroscopic observation, properties of the measurement, galaxy properties, and auxiliary observational data on the baryonic components. Using the SPARC (Spitzer Photometry &amp; Accurate Rotation Curves) sample, we find that fits to the full rotation curve exhibit a large variation in information gain between galaxies, ranging from ~1 to ~11 bits. The variation is predominantly caused by the vast differences in the number of data points and the size of velocity uncertainties between the SPARC galaxies. We also study the relative importance of the minimum $\mathrm{H}\, \small {\rm I}$ surface density probed and the size of velocity uncertainties on the constraining power on the inner halo density slope, finding the latter to be significantly more important. We spell out the implications of these results for the optimization of galaxy surveys aiming to constrain galaxies’ dark matter distributions, highlighting the need for precise velocity measurements.

FAST Drift Scan Survey for Hi Intensity Mapping: I. Preliminary Data Analysis

This work presents the initial results of the drift-scan observation for the neutral hydrogen (Hi) intensity mapping survey with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The data analyzed in this work were collected in night observations from 2019 through 2021. The primary findings are based on 28 hr of drift-scan observation carried out over 7 nights in 2021, which covers 60 deg2 sky area. Our main findings are, first, our calibration strategy can successfully correct both the temporal and bandpass gain variation over the 4 hr drift-scan observation. Second, the continuum maps of the surveyed region are made with frequency resolution of 28 kHz and pixel area of . The pixel noise levels of the continuum maps are slightly higher than the forecast assuming T sys = 20 K, which are 36.0 mK (for 10.0 s integration time) at the 1050–1150 MHz band, and 25.9 mK (for 16.7 s integration time) at the 1323–1450 MHz band, respectively. Third, the flux-weighted differential number count is consistent with the NRAO-VLA Sky Survey (NVSS) catalog down to the confusion limit ∼7 mJy beam−1. Finally, the continuum flux measurements of the sources are consistent with those found in the literature. The difference in the flux measurement of 81 isolated NVSS sources is about 6.3%. Our research offers a systematic analysis for the FAST Hi intensity mapping drift-scan survey and serves as a helpful resource for further cosmology and associated galaxies sciences with the FAST drift-scan survey.