Stable Gain Research Articles

Autonomous Vehicle State Estimation and Mapping Using Takagi-Sugeno Modeling Approach.

This paper proposes an optimal approach for state estimation based on the Takagi–Sugeno (TS) Kalman filter using measurement sensors and rough pose obtained from LIDAR scan end-points matching. To obtain stable and optimal TS Kalman gain for estimator design, a linear matrix inequality (LMI) is optimized which is constructed from Lyapunov stability criteria and dual linear quadratic regulator (LQR). The technique utilizes a Takagi–Sugeno (TS) representation of the system, which allows modeling the complex nonlinear dynamics in such a way that linearization is not required for the estimator or controller design. In addition, the TS fuzzy representation is exploited to obtain a real-time Kalman gain, avoiding the expensive optimization of LMIs at every step. The estimation schema is integrated with a nonlinear model-predictive control (NMPC) that is in charge of controlling the vehicle. For the demonstration, the approach is tested in the simulation, and for practical validity, a small-scale autonomous car is used.

Asymmetric‐fed triband antenna for military radars and 5G applications using microstrip technology

Achieving antenna size reduction while maintaining high efficiency and multiband characteristics with wide bandwidths across all the operating frequency bands is highly demanded and challenging in microstrip antennas. A novel compact triband quasi-rho-shaped and cost-effective antenna is designed on a 7 × 7 × 1 mm3 FR4 substrate having a permittivity of 4.4 and a loss tangent of 0.02. With an electrical size of 0.39λ0 × 0.39λ0 × 0.056λ0, where λ0 is the free space wavelength at 16.84 GHz, a circular slot and asymmetric microstrip feed are used to achieve the desires performance. The proposed antenna is designed, simulated, and optimized using high-frequency structure simulator (HFSS) software, and its prototype is fabricated to validate its electromagnetic performance. Furthermore, an equivalent circuit is proposed using the Foster canonical model. The proposed antenna exhibits a maximum stable gain of 5.32 dB and an average radiation efficiency of 77.87% in all the operating frequency bands. The measurement results show that the antenna covers (16.84–18.15 GHz), (24.78–27.40 GHz), and (34.47–37.22 GHz) bands centred at 17.39 GHz, 25.98 GHz, and 35.83 GHz, respectively, with a minimum wide bandwidth (S11 ≤ −10 dB) of 1.31 GHz. The acquired results illustrate that the quasi-rho-shaped antenna is suitable for military radars and 5G applications.

Design of dual band-notched UWB hexagonal printed microstrip antenna

AbstractThis article presents the design and performance analysis of a printed microstrip ultra-wideband (UWB) antenna consisting of the slots in the ground plane and radiating patch. A meandered S-shaped slot has been introduced on the patch and an inverted U-shaped slot has been incorporated in the ground plane to realize the band-notch effect for WiMAX (3.2–3.8 GHz) and WLAN (5.1–5.8 GHz) bands respectively. The total dimension of the proposed design is 44 × 44 mm2. The fabricated antenna exhibits wide impedance bandwidth of 10 GHz (2.4–12.4 GHz), i.e., 135% of center frequency. The design prototype is fabricated, and the measured results have good agreement with simulated values. The effects of the slots have been analyzed by simulated surface current distribution. The designed antenna shows almost omnidirectional radiation patter and stable gain. The proposed hexagonal antenna may be suitable for UWB applications removing WiMAX and WLAN bands.

Wideband Filtering Slot Antenna Design with Stable Gain Using Characteristic Mode Analysis.

A filtering slot antenna with a simple structure combination using characteristic mode analysis (CMA) is proposed. To realize filtering characteristics, characteristic magnetic currents of line and ring slots are analyzed and designed. Then, the folding-line slot and double-ring slot are selected to realize radiation null separately and combined to construct the basic slot antenna. By properly exciting the selected characteristic modes, a wide filtering bandwidth and a stable gain are obtained. To validate the design process, a prototype antenna with a finite ground plane of about 1.1 λ × 1.1 λ is designed and fabricated. Simulated and measured results agree well, which both show a sharping roll rate in the lower and higher frequency and a flat gain realization in the pass band. The filtering bandwidth is 32.7%, the out-of-band suppression level at the higher frequency is over 20 dB, and the gain in the working frequency varies from 3.9 to 5.2 dB.

A compact super wideband antenna with stable and improved radiation using super wideband frequency selective surface

A small bulb shaped planar super wideband (SWB) antenna with the dimension of 35 × 30 × 0.8 mm3 operating over 2.8–40 GHz (14.28:1) spectrum is proposed. The antenna offers a fractional bandwidth of 173.8%, bandwidth dimension ratio (BDR) of 1904, measured peak gain of 5.5 dBi and radiation efficiency of 80%. The proposed antenna is unified to an unique SWB frequency selective surface (FSS), having unit cell size equal to 0.114λL × 0.114λL × 0.008λL (λL is the wavelength at 3.1 GHz). The FSS operates in 3.05 to 35.92 GHz spectrum (168.7%) with transmission level S21 ≤ -10 dB and reflection S11 near 0 dB for TE and TM modes of polarization with adequate angular stability. The linearly decreasing S11 phase of FSS makes it appropriate for radiation improvement of the bulb shaped antenna in the broadside direction by placing the antenna at the top of FSS with an optimal air gap of 19 mm. The SWB ‘antenna-FSS’ exhibits wideband response over 3–36.2 GHz (169.4%) spectrum, including commercial ultra-wideband (3.1–10.6 GHz), ISM bands (5.725–5.875 GHz & 24–24.25 GHz), WiMAX (3.3–3.7 GHz), IEEE 802.11 WLAN bands, S-C-X-Ku-Ka bands, and 5G NR (n77, n78, n79, n257, n258, n261) bandwidth with stable and adequate gain of 5.2–7.16 dBi and an acceptable radiation efficiency.

A Novel Double U-Slot Microstrip Patch Antenna Design for Low-Profile and Broad Bandwidth Applications

A low-profile double U-slot microstrip patch antenna with a wide operating bandwidth has been developed in this article. This design produces the dual radiative resonant modes adjacent to each even at the thickness of the antenna of <inline-formula> <tex-math notation="LaTeX">$0.02 {\lambda _{0}}$ </tex-math></inline-formula>. An extremely stable radiation gain that varied from 6.2 to 6.8 dBi is achieved within the whole operating band. In addition, detailed parametric studies in this article provide antenna engineers with simple approximate rules that result in an excellent first-pass design with prescribed characteristics requiring only minimal tuning. Finally, the proposed antenna with the thickness of <inline-formula> <tex-math notation="LaTeX">$0.04 {\lambda _{0}}$ </tex-math></inline-formula> is fabricated and measured. Simulated and measured results are found in good agreement with each other. They have evidently illustrated that the bandwidth is increased by 50&#x0025; compared to the traditional U-slot antenna. With the help of these simple design procedures and examples in this article, antenna designers could easily develop a low-profile broadband antenna.

A wide-band continuous-beam-scanning leaky-wave antenna with a stable gain fed by spoof surface plasmon polaritons

A wide-band continuous-beam-scanning leaky-wave antenna with a stable gain fed by spoof surface plasmon polaritons

A periodic meandering microstrip line leaky‐wave antenna with consistent gain and wide‐angle beam scanning

In this article, a periodic leaky-wave antenna (LWA) with wide-angle beam scanning and stable gain is proposed based on the meandering microstrip line. Due to the meandering property of the microstrip line, the longitudinal dimension of the antenna is reduced. Firstly, the radiation characteristic of the meandering microstrip line is analyzed in detail. Each corner of the meandering microstrip line is modeled by a shunt capacitance and shunt radiation conductance to acquire the equivalent circuit. Then, the frequency balanced condition is investigated based on the established equivalent circuit to realize continuous beam scanning through broadside. Subsequently, the method of open-stop band (OSB) suppression is studied by introducing asymmetric perturbation on the LWA unit cell, which actually can be applied to eliminate the OSB effect in arbitrary symmetric LWAs. Finally, an antenna prototype is simulated and measured. The measured results agree well with the simulated results, validating the proposed method of OSB suppression. The measured results show that the designed antenna exhibits the beam scanning capacity of −47° to +76° with the frequency varying from 5.0 to 7.8 GHz and gain variation of 2.9 dB.

A Wideband Circularly Polarized Magnetoelectric Dipole Antenna for 5G Millimeter-Wave Communications.

In this paper, a wideband circularly polarized (CP) magnetoelectric (ME) dipole antenna operating at 28 GHz band was proposed for 5G millimeter-wave (mm-wave) communications. The antenna geometry included two metallic plates with extended hook-shaped strips at its principal diagonal position, and two corners of truncated metallic plates at the secondary diagonal position. The pair of metallic vias connected the modified strips to the ground plane to create the magnetic dipole. The L-shaped probe feed between the strips was used to excite the antenna. The antenna showed stable gain and wideband characteristics. The simulated and measured results showed that the proposed CP ME dipole antenna had an overlapping (|S11|< −10 dB impedance and 3 dB axial ratio) bandwidth of 18.1% (25–30 GHz), covering the frequency bands dedicated for 5G new radio communications. Moreover, an average gain of 8 dBic was achieved by the antenna throughout the operating bandwidth. The measured data verified the design concept, and the proposed antenna had a small footprint of 0.83 λo × 0.83 λo × 0.125 λo (λo is free space wavelength at the lowest operating frequency), suitable for its application in 5G smart devices and sensors.

Diabetes Mellitus Predicts Weight Gain After Surgery in Patients With Acromegaly.

ObjectiveMetabolic complications are common in patients with acromegaly. However, this occasionally does not improve post-surgery and may be related to postoperative weight gain. We aimed to investigate the postoperative weight change and factors associated with postoperative weight gain in patients with acromegaly.Design and MethodsOverall, 113 consecutive patients with body weight records pre- and 3–6 months post-surgery between October 2009 and March 2021 were enrolled. Patients were divided into three groups: weight loss (weight decrease ≥3%), stable, and weight gain (weight increase ≥3%). Hormone status, metabolic comorbidities, and anthropometric parameters were compared between the groups.ResultsAmong 113 patients, 29 (25.7%) and 26 (23.0%) patients lost and gained weight, respectively, post-surgery. There were no significant differences in baseline characteristics, including age at diagnosis, sex, body mass index, and growth hormone levels among the three groups. The prevalence of diabetes mellitus at diagnosis was significantly higher in the weight gain group than in the other groups. Patients with diabetes (n=22) had a 5.2-fold higher risk of postoperative weight gain than those with normal glucose tolerance (n=37) (P=0.006). In the diabetes mellitus group, the percentage lean mass decreased (-4.5 [-6.6–2.0]%, P=0.002), and the percentage fat mass significantly increased post-surgery (18.0 [4.6–36.6]%, P=0.003), whereas the normal glucose tolerance group did not show body composition changes post-surgery.ConclusionIn patients with acromegaly, 23% experienced ≥3% weight gain post-surgery. Diabetes mellitus at diagnosis is a significant predictor of weight and fat gain post-surgery.

Millimeter-Wave Wideband Endfire Magnetoelectric Dipole Antenna Fed by Substrate Integrated Coaxial Line

A wideband endfire magnetoelectric (ME) dipole antenna fed by substrate integrated coaxial line (SICL) is presented. Endfire radiation is achieved by the combination of a horizontally oriented quarter-wave shorted patch and a dipole array loaded at the patch aperture. A direct-feeding mechanism based on the SICL structure is developed to excite the ME-dipole antenna. The proposed feeding method provides a simple yet effective mean of wideband impedance tuning. The antenna exhibits a wide impedance bandwidth of 77%, covering from 23.1 to 52 GHz, and a small lateral size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.32\lambda _{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> refers to the wavelength in free space at the center frequency, i.e., 38 GHz). In addition to its wideband performance and compactness, highlights, including a stable gain of around 5.5 dBi, low backward radiation, and low cross polarization, are also achieved. In particular, the proposed design outperforms most state-of-the-art millimeter-wave endfire antennas with a notable bandwidth.

A Compact Asymmetrical Triangular Truncated Polygon Super Wideband Microstrip Antenna for Wireless Communication Applications

The rapid growth in wireless communications of today’s era requires a new generation of antennas whose operating frequency range is greater than the FCC allocated UWB (3.1-10 GHz) frequency range and also operate simultaneously for multiple communication standards in single band of frequency. Microstrip antennas technology provides these features. A ubiquitous compact asymmetrical triangle truncated polygon structure monopole fed super wideband microstrip antenna for wireless communication is proposed in this paper. The antenna uses a compact size of 50X40 mm.2 The irregular tapered truncations on patch geometry have potential effects on enlargement of operating frequency band. The antenna is designed using modified epoxy substrate material of ε= 4.2, h=1.6 mm at 3 GHz, fabricated and measured. The measured results confirm that the antenna has operating frequency band of 1.2-20.03 GHz (177.39%) with bandwidth ratio of 16:1. The antenna has stable radiation patterns and consistent gain over operating band. The time domain group delay of antenna is within 4 ns, which indicates good linear phase response. Furthermore, this proposed antenna is able to cover the DVB-H in L-band for PMP (1.45-1.49 GHz), DCS, PCS, UMTS, Bluetooth, WiMAX2500, LTE2600 and UWB bands applications.

Highly Efficient Dual-Beam Frequency Scanning Based on SSPPs With Parasitic Patch Array

A leaky-wave antenna (LWA) realizes radiation of travelling wave along guiding structures. Periodic modulation is an effective approach to turn non-radiating modes into radiating modes. A high-efficient LWA based on spoof surface plasmon polaritons (SSPPs) loaded with parasitic patch array is proposed. Sinusoidal modulation is used for the radiation of SSPPs, while parasitic array mitigates the open stopband (OSB) effect. A prototype is fabricated and measured. The measured and simulated results agree well with each other. Such design shows wide angle coverage of 83° from backward to forward and stable gain distribution of about 12 dB within the whole operating band.

Isolation and Gain Improvement of a Rectangular Notch UWB-MIMO Antenna

This paper presents the performance improvement of a co-planar waveguide rectangularly notched UWB-MIMO antenna. The isolation and gain of the antenna are enhanced by using a parasitic isolator. The antenna consists of four microstrip patch antennas and an isolator. The UWB characteristic of the antenna is achieved by truncating the lower ends of the radiating patch by a semicircle. The rectangular notch characteristic is obtained by adding two electromagnetic bandgap structures on the backside of the antenna, which is attached to the radiator via shorting pin. The performance, especially the decoupling of the MIMO antenna is improved by using a novel parasitic decoupler, which is placed between the antennas to receive uncorrelated signals. The decoupling structure consists of a square shape metallic element with a circular slot inside and a half-semicircle slot edged at each corner. Four rectangular metallic stubs are extended from opposite parallel sides to improve further isolation. The simulated and measured results show that the antenna has a rectangular notch band (5.25–5.85 GHz) across the working band of 3–12.8 GHz. In addition, the antenna has a planar structure with an overall size of 60 × 60 × 1.52 mm3 and offers stable gain, reduced mutual coupling (<−21 dB), and lower envelop correlation (<0.001).

A Wideband Cryogenic Readout Amplifier with Temperature-Insensitive Gain for SNSPD.

This paper presents a temperature-insensitive wideband cryogenic amplifier for superconducting nanowire single-photon detectors (SNSPD). With a proposed folded diode-connected transistor load to realize a good device-tracking feature, the theoretical derivations the simulations and test results prove that the amplifier-gain cell has a stable gain performance over a wide temperature range, solving the issues of a lack of the accurate cryogenic device models. The amplifier achieves a gain of 26 dB from 100 kHz to 1 GHz at 4.2 K, consuming only 1.8 mW from a 1.8 V supply. With a 0.13-μm SiGe BiCMOS process, the chip area is 0.5 mm².

Design and Analysis of Double CDRA with Extended Wideband Characteristics for C- and X-Band Applications

In this article, the design and analysis of a double cylindrical dielectric resonator antenna (CDRA) of compact size 40 × 40 mm2 with extended wideband characteristics for C- and X-band applications is presented. A couple of CDRA is placed over the two adjoin rectangular slots which are excited by a modified microstrip feed line of 50 Ω. The proposed double CDRA resonates between frequency band 4.75 and14.43 GHz with 100.93% (9.68 GHz) impedance bandwidth. Two adjoin rectangularslots with a modified microstrip feed line generate two orthogonal degenerated hybrid modes (HEMx 11δ and HEMy 11δ), which are liable for the creation of circular polarization characteristics between the frequency band 6.62 and 8.5 GHz with 24.86% (1.88 GHz) 3-dB axial ratio bandwidth. The stable peak gain of 6.27 dB at frequency 12.62 GHz, whereas the gain of 3.31–6.27 dB and radiation efficiency of more than 86% in the entire operating band is obtained.

Compact-Size Ultra-Wideband Circularly Polarized Antenna With Stable Gain and Radiation Pattern

A novel ultra-wideband (UWB) circularly polarized (CP) antenna array with sequential phase feed is proposed in this article. The element implements a multiresonance monopole to achieve UWB CP radiation. To investigate the CP operating mechanism, characteristic mode analysis is used to provide different modes at various frequencies. The simulated characteristic mode analysis results show that this element can realize good CP at three independently adjustable frequencies (2.4, 3.8, and 5.8 GHz). By combining these three frequencies, a UWB CP antenna element is realized from 2.02 to 6.03 GHz for axial ratio (AR) less than 3.0 dB. Because the main radiating region of this element changes at different frequencies, a compact 2 <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> 2 array, whose profile is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.09\lambda $ </tex-math></inline-formula> (where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> is the wavelength in free space at the lowest operating frequency), is designed and optimized to achieve higher realized gain and stable radiation pattern. Subsequently, a prototype of this array is fabricated and measured. Measured results demonstrate an overlapping bandwidth of 120.9% from 1.8 to 7.3 GHz, in terms of the −10 dB reflection coefficient bandwidth and 3 dB AR bandwidth. This array has the advantages of simple structure, compact size, high gain, and stable pattern within the entire operating band.

Compact antipodal Vivaldi antenna design with gain enhancement and notched-band characteristics based on D-CRLH metamaterial

A novel compact ultra-wide band (UWB) antipodal Vivaldi antenna with band notched is presented in this communication. T-shaped slot is introduced to extend the lower end limitation of the frequency band from 1.65 GHz to 1.25 GHz, the miniaturization of the antenna is realized. Then a new thought of the gain enhancement, namely the substrate cutout (SCO) is demonstrated to increase antenna gain, which makes the electromagnetic wave get rid of the bondage of the substrate, reducing the edge diffraction, and thus radiates more effectively, without changing the overall dimension of the antenna. The advantage is of great value in limited space especially. Then a compact unit cell based on Dual Composite Right-Left Handed (D-CRLH) metamaterial is proposed to realize the notched band characteristics in the WLAN band (4.95–5.15 GHz). In addition, the passband would be less affected by the notched band due to the sharp transition band between notched and operating band. Finally, the antenna is successfully simulated and measured, it shows broadband matched impedance, stable gain and radiation pattern over the operating band. The experimental results are also given and show a good agreement with the simulated results.

Trajectories of body weight change and survival among mCRC patients treated with systemic therapy: Pooled analysis from the ARCAD database.

80 Background: Higher baseline body mass index is associated with improved survival in metastatic CRC (mCRC). Whether weight gain or loss after mCRC diagnosis is associated with survival remains largely unknown. Methods: We analyzed individual patient data from 3504 patients with previously untreated mCRC enrolled in five phase III randomized trials (AVF2017g, AVF2192g, CRYSTAL, N9741, OPUS) conducted between 2000 and 2006. Weight measurements were prospectively collected at 3 months after diagnosis and then up to 5 years. Patients were categorized into three groups based on the percent weight change at 3 months: stable weight or gain, weight loss up to 5% of baseline weight, and ≥5% weight loss of baseline weight. Cox models were used to assess the prognostic associations of weight change at 3 months with overall survival (OS) and progression-free survival (PFS), adjusting for baseline BMI, age, sex, performance score, chemotherapy backbone (oxaliplatin vs. irinotecan), and biologics type (cetuximab vs. bevacizumab). Sub-analyses included Cox models adjusted for additional clinical-pathological factors (primary tumor sidedness [right colon vs. left colon-rectum], and BRAF status; N=1,511). Results: Median percent weight change at 3 months was -0.5% (IQR -4.0 to+1.6%). OS was better in patients with weight stability or gain than in those with weight loss (up to 5% or ≥5%; (Table). Results were consistent for PFS for patients with ≥5% weight loss of baseline weight, as well as for sub-analyses. Conclusions: Patients losing weight during the first 3 months of systemic therapy for metastatic colorectal cancer have significantly shorter overall survival than those with stable or increasing weight. Degree of weight loss is proportional to the observed increased risk of death and remains evident among underweight, normal weight and obese individuals. Further studies examining possible usefulness of on-treatment early weight loss as a novel intermediary end-point are needed.[Table: see text]

Adaptive Transmit Beamspace Optimization Design based on RD-log-FDA Radar

Because of the range-angle dependency in random log frequency diverse array (RD-log-FDA) radar, a method for designing beamspace transformation matrix in angle and range based on the receive signal has been proposed. It is demonstrated that the designed beamspace transformation matrix basically meets the requirements of beam gain. However, there are some problems in the transformation matrix designed, such as unstable beam gain and high sidelobe. Hence, we propose an optimization method by adjusting array element spacing and random number in frequency offset to get the optimum beam gain. Therefore, particle swarm optimization (PSO) is used to find the optimal solution. The beam gain comparison before and after the optimization is obtained by simulation, and the results show that the optimized array after beamspace preprocessing has more stable beam gain, lower sidelobe, and higher resolution in parameter estimation. In conclusion, the RD-log-FDA is capable of forming desired beam gain in angle and distance through beamspace preprocessing, and suppressing interference signals in other areas.