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The use of equivalent sources for the analysis of antenna arrays for high computational efficiency has been proposed. A single antenna element has been designed, and the fields have been saved on an enclosed geometry. The surface equivalence principle has been utilized to calculate the far‐field patterns from the fields saved on the enclosed geometry which has been termed as Huygens' box (HB). The antenna element has been used to design 2×1 $2\times 1$, 4×1 $4\times 1$, 8×1 $8\times 1$, and 16×1 $16\times 1$ array and the far‐fields have been calculated. For linear arrays of HBs far‐field patterns and computation time have been compared with that of the actual antenna array. As the number of elements increases from 4 to 16, the computation time has been found to reduce from 6% $6 \% $ to 47% $47 \% $. Further, the computation time has been found to reduce by 39% $39 \% $ and 75% $75 \% $ for 2×2 $2\times 2$ and 4×4 $4\times 4$ configurations, respectively. The method is suitable for analysis of complex geometry of antennas used in 5G technology and beyond. [ABSTRACT FROM AUTHOR]

Irrigation is one of the major consumers of fresh water but crops consume only a small part of supplied water and huge quantities emerge downstream as rejuvenated flow and recharge groundwater. The assessment of these flows is cumbersome due to dependence on multiple factors; hence a fixed percentage is assumed by government agencies for designing downstream projects. Three different modeling and measurement techniques, i.e., water balance, isotopic analyses, and hydrological modeling were used to compute surface and sub-surface components of irrigation return flow in an irrigation project (Sanjay Sagar Project with the capacity of 82 MCM and 9863 ha command area) situated in the hard rock region of Central India. The water balance analysis confirmed that a major portion ranging from 12.3 to 35.9%, with an average of 22.9% of supplied water to the command reached the Bah River as regenerated flow, while 1.9–16% with an average of 10.2% of supplied water reached the groundwater body as recharge. The isotopic analysis yielded qualitative insights into the proportional influence of irrigation water on open wells and bore wells in the range of 81% and 9%, respectively. The outcomes of the SWAT model demonstrated that within Sanjay Sagar's command, irrigation led to approximately 27.8% of regenerated flow and 8.9% of recharge from applied irrigation. [ABSTRACT FROM AUTHOR]

The periodic assessment of the revised capacity is essential and conventional techniques through bathymetric surveys and inflow-outflow techniques are time and resource intensive. The application of optical remote sensing data is practiced for a long time to compute the revised capacity of the reservoir but has the limitation of selecting threshold values and inefficacy of the method during the cloudy season. This research proposed the application of the Otsu segmentation technique in Google Earth Engine (GEE) to determine revised water spread using microwave remote sensing data. The Otsu technique is efficient in classifying the image into two distinct classes using within and between-class variances. An application has been developed using Sentinel data in GEE, which has the capacity of cloud-based computing and applied to the four reservoirs of Mahanadi Reservoir Project (MRP) namely Ravishankar Sagar, Murumsilli, Dudhawa, and Sondur reservoir in the Chhattisgarh state of India. The original capacities of these reservoirs vary from 910.51 MCM of Ravishankar (RS) Sagar to 165.89 MCM of Murumsilli reservoir. The revised water spreads computed in the GEE were further used to compute revised volume and in turn the revised cumulative capacities at different levels. The analysis suggested that 17.65% of dead storage (118.26 MCM from 143.00 MCM) and 9.25% of gross storage (85.26 MCM from 910.52 MCM) of RS Sagar has been lost in 42 years (1978 to 2020). Similarly, 10.33% gross capacity of Murumsilli, 13.12% of Sondur, and 12.37% of Dudhawa reservoirs have been lost due to the deposit of sediments from the catchments, and results were found comparable with bathymetric survey results of three reservoirs. The proposed application has been developed in GEE so it can be used in any part of the world in cloudy weather with no human interference. [ABSTRACT FROM AUTHOR]

The quality of speech degradeswhile communicating over Voice over Internet Protocol applications, for example, Google Meet, Microsoft Skype, and Apple FaceTime, due to different types of background noise present in the surroundings. It reduces human perceived Quality of Experience (QoE). Along this line, this article proposes a novel speech quality prediction metric that can meet human's desired QoE level. Our motivation is driven by the lack of evidence showing speech quality metrics that can distinguish different noise degradations before predicting the quality of speech. The quality of speech in noisy environments is improved by speech enhancement algorithms, and for measuring and monitoring the quality of speech, objective speech quality metrics are used. With the integration of these components, a novel no-reference context-aware QoE prediction metric (CAQoE) is proposed in this article, which initially identifies the context or noise type or degradation type of the input noisy speech signal and then predicts context-specific speech quality for that input speech signal. It will have of great importance in deciding the speech enhancement algorithms if the types of degradations causing poor speech quality are known along with the quality metric. Results demonstrate that the proposed CAQoE metric outperforms in different contexts as compared to the metric where contexts are not identified before predicting the quality of speech, even in the presence of limited size speech corpus having different contexts available from the NOIZEUS speech database. [ABSTRACT FROM AUTHOR]

To meet the human perceived quality of experience (QoE) while communicating over various Voice over Internet protocol (VoIP) applications, for example Google Meet, Microsoft Skype, Apple FaceTime, etc. a precise speech quality assessment metric is needed. The metric should be able to detect and segregate different types of noise degradations present in the surroundings before measuring and monitoring the quality of speech in real-time. Our research is motivated by the lack of clear evidence presenting speech quality metric that can firstly distinguish different types of noise degradations before providing speech quality prediction decision. To that end, this paper presents a novel non-intrusive speech quality assessment metric using context-aware neural networks in which the noise class (context) of the degraded or noisy speech signal is first identified using a classifier then deep neutral networks (DNNs) based speech quality metrics (SQMs) are trained and optimized for each noise class to obtain the noise class-specific (context-specific) optimized speech quality predictions (MOS scores). The noisy speech signals, that is, clean speech signals degraded by different types of background noises are taken from the NOIZEUS speech corpus. Results demonstrate that even in the presence of less number of speech samples available from the NOIZEUS speech corpus, the proposed metric outperforms in different contexts compared to the metric where the contexts are not classified before speech quality prediction. [ABSTRACT FROM AUTHOR]

In this article, a wideband low‐profile endfire circularly polarized (CP) antenna using magnetoelectric dipole is proposed. Designing a wideband electric dipole element is easy and well‐studied in the literature. However, designing a compact wideband magnetic dipole element is still a challenge. In this paper, the impedance bandwidth (IBW) of the magnetic dipole is enhanced by reducing the resonance frequency of higher‐order mode half‐TE310 with the help of rectangular slots placed at the null of mode half‐TE310. By combining the resonance frequency of mode half‐TE110 and mode half‐TE310, the magnetic dipole can yield a larger IBW (6.86–7.67 GHz, 11.14%) with smaller planar dimensions of 1.259λ0 × 0.363λ0 × 0.038λ0 (λ0 is the free space wavelength at the centre frequency). To generate a wideband endfire CP wave, a horizontally polarized electric dipole with a feed line is combined with the vertically polarized magnetic dipole. The measured IBW and axial ratio bandwidth (ARBW) are 11.65% and 12.02%, respectively, with a measured peak endfire gain of 5 dBic. The overall dimension of the proposed wideband low‐profile endfire CP antenna is 1.11λ0 × 0.66λ0 × 0.033λ0. [ABSTRACT FROM AUTHOR]

Speech enables easy human-to-human communication as well as human-to-machine interaction. However, the quality of speech degrades due to background noise in the environment, such as drone noise embedded in speech during search and rescue operations. Similarly, helicopter noise, airplane noise, and station noise reduce the quality of speech. Speech enhancement algorithms reduce background noise, resulting in a crystal clear and noise-free conversation. For many applications, it is also necessary to process these noisy speech signals at the edge node level. Thus, we propose implicit Wiener filter-based algorithm for speech enhancement using edge computing system. In the proposed algorithm, a first order recursive equation is used to estimate the noise. The performance of the proposed algorithm is evaluated for two speech utterances, one uttered by a male speaker and the other by a female speaker. Both utterances are degraded by different types of non-stationary noises such as exhibition, station, drone, helicopter, airplane, and white Gaussian stationary noise with different signal-to-noise ratios. Further, we compare the performance of the proposed speech enhancement algorithm with the conventional spectral subtraction algorithm. Performance evaluations using objective speech quality measures demonstrate that the proposed speech enhancement algorithm outperforms the spectral subtraction algorithm in estimating the clean speech from the noisy speech. Finally, we implement the proposed speech enhancement algorithm, in addition to the spectral subtraction algorithm, on the Raspberry Pi 4 Model B, which is a low power edge computing device. [ABSTRACT FROM AUTHOR]

In this letter, a single-layer compact copolarized shorted TM1/2,0 mode microstrip patch antenna is presented for in-band full-duplex application. Two shorted TM1/2,0 mode patch antennas, used for transmission and reception purposes, make the structure compact. The wideband behavior of the patch antenna is obtained by fusing the two resonances, one because of the shorted TM1/2,0 mode radiating patch and the other because of the λ/4 line resonator. To enhance the isolation between the transmitter and receiver antenna, a novel defected ground structure is used. Slots are introduced into the ground plane to create a weak field region for the basic antenna element. The other antenna element (receiver) is located in the weak field region to enhance isolation. Further enhancement in isolation is achieved by introducing a T-shaped metallic strip into the slots. The structure is proposed with the credits of compactness, enhanced bandwidth, colinear polarization, very less fabrication complexity, low profile, and high isolation. The proposed structure is fabricated and measured. The structure experimentally exhibits a bandwidth (≤ −10 dB) of 2.42–2.52 GHz with the isolation of 25 dB, peak isolation of 36 dB, and an average realized gain of 4 dBi in the entire band. [ABSTRACT FROM AUTHOR]

Recognizing background information in human speech signals is a task that is extremely useful in a wide range of practical applications, and many articles on background sound classification have been published. It has not, however, been addressed with background embedded in real-world human speech signals. Thus, this work proposes a lightweight deep convolutional neural network (CNN) in conjunction with spectrograms for an efficient background sound classification with practical human speech signals. The proposed model classifies 11 different background sounds such as airplane, airport, babble, car, drone, exhibition, helicopter, restaurant, station, street, and train sounds embedded in human speech signals. The proposed deep CNN model consists of four convolution layers, four max-pooling layers, and one fully connected layer. The model is tested on human speech signals with varying signal-to-noise ratios (SNRs). Based on the results, the proposed deep CNN model utilizing spectrograms achieves an overall background sound classification accuracy of 95.2% using the human speech signals with a wide range of SNRs. It is also observed that the proposed model outperforms the benchmark models in terms of both accuracy and inference time when evaluated on edge computing devices. [ABSTRACT FROM AUTHOR]

A compact five-port multi-input multi-output (MIMO) antenna for n79 (4.4–5 GHz) 5G band exhibiting pattern and polarization diversity with good isolation is proposed in this paper. This MIMO antenna system comprises of four linearly polarized (LP) endfire monopole antenna elements and one broadside L-shaped slot circularly polarized (CP) antenna element, which provides both pattern and polarization diversity. A T-shaped slot as a decoupling structure is further used to improve the interport isolation by 4 dB. The return loss bandwidth for all antenna elements is in the desired frequency range, and antenna elements provide isolation better than 23 dB. The pattern and polarization diversity provide a low envelope correlation coefficient and good isolation between any two-port of the MIMO antenna. For experimental verification, the proposed 5-port MIMO antenna system is fabricated and measured, which provides decent agreement with the simulated performance. [ABSTRACT FROM AUTHOR]

In this letter, a miniaturized triband printed monopole antenna with circular polarization (CP) characteristic has been designed and demonstrated. The proposed geometry is comprised of two orthogonal stubs and one meander pattern on the top layer and a defected ground plane. By carefully designing the top and bottom layer topologies, the antenna is made significantly compact having an overall size of 0.26λ × 0.28λ × 0.017λ, where λ denotes the free space wavelength at the lowest CP frequency. The geometry exhibits a wide 10‐dB impedance bandwidth of 53.63% (3.22–5.58 GHz) covering three distinct CP resonances appearing at 3.30, 4.50, and 5.40 GHz. The structure has been fabricated and the measured responses show a reasonable agreement with the simulated results. The proposed antenna has a simple topology, broadside radiation, moderate gain, and an improved miniaturization performance as compared to the earlier reported multi‐band CP antennas. [ABSTRACT FROM AUTHOR]

In this paper, a compact triple-band printed monopole antenna with circular polarization (CP) has been presented for C-band wireless applications. To achieve the triple-band CP response, the top layer of antenna geometry consists of a meander structure and two orthogonal stubs, whereas a ground plane consists of a vertical slot. The 10-dB impedance bandwidth of the proposed antenna is 450, 560, and 830 MHz at center frequencies of 4.1, 5.8, and 6.7 GHz, respectively. The 3-dB axial ratio (AR) bandwidth's attained around center frequencies is 4.29%, 4.03%, and 3.52%, respectively. Additionally, the proposed design exhibits a miniaturized performance with an overall size of 0.35 × 0.39 × 0.017 λ, where λ represents free space wavelength at smallest CP frequency. Furthermore, the structure has a simple topology, broadside radiation, and sufficient moderate gain. The proposed antenna has been fabricated and its measured responses are in good agreement with the simulated results. [ABSTRACT FROM AUTHOR]

A dual‐band, dual‐polarized in‐band full‐duplex antenna with good isolation performance is presented for wireless local area network (WLAN) applications. A neutralization line is connected between the grounds of the transmitter (Tx) and receiver (Rx) antennas to enhance the isolation. Further enhancement in isolation is achieved by using a 180° ring hybrid coupler between receiving antenna elements. Here the dual‐band monopole antennas are used as transmitting and receiving antenna elements. For better isolation, the receiving antenna elements are placed opposite to each other and fed through the differential ports of the 180° ring hybrid coupler. The proposed structure is fabricated, and the comparison of measured results and simulated results are studied. The simulated and measured impedance bandwidths (≤−10 dB) of the antenna cover the entire 2.4 GHz WLAN band (2.4–2.48 GHz), and for this band, the measured isolation is better than 40 dB. For the higher band, the measured isolation is more than 40 dB for 200 MHz (5.15–5.35 GHz) of bandwidth. The simulated radiation patterns of the antenna are well‐matched with the measured patterns at both the frequencies. [ABSTRACT FROM AUTHOR]

In this article, a three‐port circularly polarized (CP) multiple‐input multiple‐output (MIMO) antenna for wireless local area network (WLAN) application with pattern and polarization diversity is proposed. The proposed MIMO antenna system comprises of a broadside CP antenna element with a T‐shaped slot and two endfire CP antenna elements. Good impedance bandwidth of 16.9% and 5.5% are achieved by the broadside CP antenna and endfire CP antenna, respectively, and their corresponding axial ratio (AR) bandwidth is 7% and 10.47%. The isolation between the different antenna elements is better than 20 dB, and the polarization purity for all CP antenna is more than 25 dB along with the maximum radiation. [ABSTRACT FROM AUTHOR]

The 'Normalized Antecedent Precipitation Index (NAPI)' model developed based on water balance equation was found capable to predict runoff yields from ungauged catchment when its parameters estimated from the gauged catchment are updated using the linear relationship of geomorphologic parameters of an ungauged to that of the gauged catchment, and cumulative geomorphologic index (CGI). The CGI was developed by assigning a relative weight on each geomorphologic parameter multiplied by the ratio of characteristic value of that parameter of the ungauged and gauged catchment. Influence of land-use and land-cover (LULC) on the model's parameters was also analyzed by developing an index for LULC. The NAPI model has three parameters and its mathematical structure has rational form and the parameters possessed resonance with curve number (CN) of the SCS (Soil Conservation Services) model. The NAPI model demonstrated ability to simulate rainfall-runoff events both as direct and inverse problem. Performances of the model to predictions of runoffs from ungauged catchments were also tested with the data of two observation sites of the Bina basin in Madhya Pradesh (India) considering the data of one site as the runoffs from the ungauged catchment. The results exhibited a close match between the computed and observed values when the model's parameters were also updated by the index of LULC. [ABSTRACT FROM AUTHOR]

As most of the bio-molecules sizes are comparable to the terahertz (THz) wavelength, this frequency range has spurred great attention for bio-medical and bio-sensing applications. Utilizing such capabilities of THz electromagnetic wave, this paper presents the design and analysis of a new non-intrusive and label-free THz bio-sensor for aqueous bio-samples using the microfluidic approach with real-time monitoring. The proposed THz sensor unit utilizes the highly confined feature of the localized spoof surface plasmon (LSSP) resonator to get high sensitivity for any minute change in the dielectric value near it's surface. The proposed sensor, which is designed at 1 THz, exploits the reflection behavior (S11) of the LSSP resonator as the sensing response. The proposed sensor has been designed with a high-quality factor of 192 to obtain a high sensitivity of 13.5 MHz/mgml-1. To validate the proposed concept, a similar sensor unit has been designed and implemented at microwave frequency owing to the geometry dependent characteristics of the LSSP. The developed sensor has got a highly sensitive response at microwave frequency with a sensitivity of 1.2771e-4 MHz/mgml-1. A customized read-out circuitry is also designed and developed to get the sensor response in terms of DC-voltage and to provide a proof of concept for the low-cost point of care (PoC) detection solution using the proposed sensor. It is anticipated that the proposed design of highly sensitive sensor will pave a path to develop lab-on-chip systems for bio-sensing applications. [ABSTRACT FROM AUTHOR]

This paper reports a label-free, highly sensitive plasmonic metamaterial inspired multi-band planar microwave sensor for aqueous biological samples. The proposed sensor consists of a spoof surface whispering gallery mode (SS-WGM) resonator connected to a spoof surface plasmons polariton (SSPP) transmission line in a special arrangement. The SS-WGM resonator of the proposed sensor is capable of localizing the electromagnetic (EM) field into a specific region due to its slow-wave propagation characteristics. This feature enhances the interaction time of the sample under test (SUT) with EM wave and offers higher sensitivity. The EM wave localization enables the proposed design to sense the small volume of the bio-samples. This is required in the case of the aqueous samples because a large volume of SUT absorbs radio frequency (RF) signals and reduces the ${Q}$ -factor of the sensors. The microfluidic approach has been adopted as it supports a small sample size. The proposed sensor is numerically analyzed and optimized for multi-band capability using full-wave EM simulation. To ensure maximum sensitivity, the microfluidic channel is kept appropriately above the hot-spot of the sensor. Glucose aqueous solution is being used here as a biological sample. Experimental validation of the proposed approach has been done using different concentrations of the SUT. The proposed sensor offers a maximum measured sensitivity of 77.3e−02 MHz/mgml−1, which shows a fair improvement in the sensitivity as compared to the state-of-the-art. It is anticipated that the proposed microfluidic planar microwave sensor is paving the path for the development of the microwave-based modern lab-on-chip system arrangement. [ABSTRACT FROM AUTHOR]

This article presents the amplification of the propagating spoof surface plasmon polariton (SSPP) modes in the ring resonator-based filtering structure. SSPP-based corrugated ring resonator has been used to design a high- $Q$ dual-band bandpass filter (BPF). Afterward, a subwavelength scale amplifier has been embedded on the output port of the designed BPF to provide loss-compensation as well as amplification at the specified frequency bands of the filtering structure. A microwave laminate with a dielectric constant of 3.38 and a height of 1.52 mm is used to develop the proposed circuit. An 8.2 and 9 - dB gains have been obtained at the two frequency bands, respectively. Good agreement has been achieved between simulated and measured results. The proposed loss compensation and amplification of the SSPP modes in the ring resonator-based structure paves a path to develop active biosensing applications and ultracompact spoof plasmonics-based radio frequency (RF)-to-terahertz (THz) transceiver systems. [ABSTRACT FROM AUTHOR]

The water availability assessment is an important aspect for planning and management of water resources in the basin; however, non-availability of observed runoff is an important issue often found in the developing countries. The farmers of irrigation projects incur more expenditure due to assured supply and suffer huge economic loss in dry years. In the present study, a water balance of reservoir for computation of runoff coupled with the application of spatially distributed Soil and Water Assessment Tool (SWAT) model, the SWAT model and SWAT–CUP application have been proposed for hydrological modeling can be used asses the inflows for efficient reservoir operation and planning of releases. The proposed methodology has been applied on Tandula reservoir catchment in Chhattisgarh state of India, which is well-known for its paddy cultivation and any short supply affect the economic status of marginal farmers in the command. The water balance of Tandula reservoir has been carried out for the period of 1991 to 2015 using daily reservoir levels, releases, evaporation, seepage, supplies from other sources, and spillway information. The percentage error in water balance analysis of Tandula reservoir varied between − 6.87 and 3.39% and seem reasonably well matched. The runoff obtained from water balance was checked with the SCS–CN technique and found close resemblance on the monthly and yearly basis. The digital image processing of remote sensing data has been used for determination of land uses and found that forest and agriculture land with rice cultivation are the principal land uses covering nearly 86% area of the catchment. The sensitivity analysis suggested that SCS curve number (r_CN2), saturated hydraulic conductivity (sol_k), soil antecedent water content (sol_AWC), and Manning's N for the main channel (Ch_N2) are the most sensitive parameters. The sequential uncertainty fitting (SUFI2) technique has been used for calibration of model for the period of 1995 to 2007 and validated for 2008 to 2015. The model performance was adjudged using P-factor, r-factor, and Nash–Sutcliff efficiency, and best-fit model parameters were determined. The Nash–Sutcliff efficiency for calibration and validation were found as 0.75 and 0.65 respectively suggested that the developed model can be used for assessment of runoff from the catchment. The knowledge of the availability of water using the amalgamation of water balance, SWAT model, and SWAT CUP application can be used for reservoir operation, irrigation management, and assessment of the impact of climate and land use change on runoff from the catchment. [ABSTRACT FROM AUTHOR]

The declining baseflow and drying up of river during the lean period are important issues in major rivers systems in India. In recent times, more focus has been given to formulate an action plan for river rejuvenation. The present study aims at the assessment of declining flow regime in Shipra river in the Madhya Pradesh state of India. Long-term daily runoff data recorded at the Ujjain gauge discharge site on Shipra river was analyzed to identify trends in dependable flows using a non-parametric Mann–Kendall test. The declining trend for dependable river flow at various probability levels was observed at Ujjain during the beginning of monsoon (month of July) and at the end of monsoon (months of September and October). However, a rising trend was observed during the mid-monsoon season (month of August). The trend analysis of pre-monsoon and post-monsoon groundwater level data indicated falling groundwater level trend in the entire Shipra basin. Significant declining trends in groundwater levels were observed in the middle reach area of the basin where important cities like Indore and Ujjain are located. Wigley and Jones's index was used to judge the rising or declining flow regime of Shipra river. Average annual rainfall, as well as river runoff, has decreased substantially during the last two decades. The trend analysis of flow and groundwater level data of the Shipra river basin and information derived using Wigley and Jones index will be useful to formulate strategies for the river rejuvenation planning. [ABSTRACT FROM AUTHOR]

In this study, we report a design concept to obtain center frequency and bandwidth reconfigurable spoof surface plasmon polaritons (SSPP) band-pass filter using T-shaped spoof SPP resonator. The design, analysis, and implementation of the proposed filter have been given with detailed mathematical analysis. Tuning has been performed using varactor diode which is introduced at different positons in the T-shaped resonator. Since spoof SPP has high field confinement and enhancement, hence it offers low crosstalk and mutual coupling as compared with conventional microstrip which is desirable to make low-loss system. The filter has been fabricated using a 1.52-mm-thick microwave laminate and characterization has been done using Keysight Field-Fox analyzer N9918A. The fabricated filter has a reconfigurable center frequency from 4.2 to 4.4GHz with insertion loss ~4.2 dB and bandwidth reconfigurable from 4.12 to 4.52GHz with ~3.8 dB insertion loss in the tuning range. The proposed reconfigurable band-pass filter will pave an important role in the designing and developing of the flexible plasmonic circuits and systems. [ABSTRACT FROM AUTHOR]

In this letter, we report the design theory and analysis of an end-coupled broadband spoof plasmonic based band-pass filter (BPF) at sub-wavelength scale enabled by multi-mode grooved stepped impedance resonators (GSIRs) at THz frequency regime. The proposed GSIRs are end-coupled to each other and externally coupled to the source and load through spoof surface plasmon polaritons (SPP)-based transmission line. The designed filter has 3-dB bandwidth of 0.35 THz (from 0.17 THz to 0.52 THz) and fractional bandwidth (FBW) of 87.85%, respectively, with the shape factor of 1.35. The simulated transmission and reflection coefficients in the pass-band of proposed filter are better than ∼6 dB and 15 dB respectively. Also, 60 dB spurious rejection bandwidth of the designed filter in the upper stop-band is 1.3 THz (0.62–1.92 THz). For the validation of the proposed approach, similar design is implemented at microwave frequency due to the geometrical dependence feature of spoof SPP and its S-parameters response is presented. Such broadband BPF will pave a path to design and development of advanced integrated plasmonic circuits and systems for high-speed and low-loss THz wireless communication applications. [ABSTRACT FROM AUTHOR]

In this paper, we report the design, analysis, and development of spoof surface plasmon polariton (SSPP)-based reconfigurable band-pass filter using a planar ring resonator. A transition from quasi-transverse electromagnetic (QTEM) mode of microstrip to SSPP mode was implemented which has been subsequently used to develop a reconfigurable band-pass filter. Trapezoidal shape periodically corrugated metallic grooves etched on the planar metallic surface have been used in the implementation of this transition. In the designed transition, impedance and mode matching between QTEM mode and SSPP mode have been achieved using gradient grooves. The developed transition has been used in the characterization of a ring resonator corrugated with the periodical array of the trapezoidal shape grooves. This SSPP ring resonator shows multiple passbands at different frequencies within the specified frequency range. Varactor diodes have been incorporated in the SSPP ring resonator to obtain tunable passband. Three types of varactor-tuned circuits have been experimentally implemented and characterized using SMV2019-079LF diode package. These circuits will pave the path for development of other front-end circuit elements using the concept of spoof SPP. [ABSTRACT FROM AUTHOR]

Dams or reservoirs have proven to be very beneficial for the sustained development of human beings since its evolution. The usefulness of dam depends upon its capacity to store water. Sedimentation is a process which involves deposition of silt carried by flowing water from erosion of soil of upstream catchment area. Sedimentation has proven to be very detrimental for the capacity of dams or reservoirs. Sedimentation results in huge loss of storage capacity of dams or reservoirs thus reducing its life. Many methods have developed to measure the reservoir sedimentation like hydrographic survey, inflow-outflow approaches, remote sensing method etc. Out of these, remote sensing method is widely used as it is very simple and involves very less human survey thus reducing the chances of error. In remote sensing method, revised water spread area at different levels of reservoir is calculated and used for computation of loss of capacities between these levels. The present study has been carried out on Kharkhara reservoirs situated in Chhattisgarh state. Multi-date satellite data of IRSP6, LISS-III is used for Kharkhara dam to estimate revised capacity. The normalized difference water index (NDWI), band ratioing technique (BRT) and false color composite (FCC) along with field truth verification were used to differentiate water pixels from rest of image. As the revised water spread at dead storage and full reservoir levels were not available, best -fit curve has been used to get revised spreads on these levels. From the analysis, it has been observed that Kharkhara reservoir has lost 8.41 MCM of gross storage against its total capacity of 169.54 MCM during 50 years(1967-2017). The average rate of sedimentation in Kharkhara reservoir is 16.82 Ha-m per year. [ABSTRACT FROM AUTHOR]

This letter reports the design and analysis of the bandwidth (BW) reconfigurable band-pass filter using spoof surface plasmon polaritons at THz/microwave frequency. The designed filter consists of a spoof SPP T-shape resonator in which tuning has been introduced using variable capacitor device (having a cutoff frequency in THz regimes). Even and odd mode analysis has been carried out for a better understanding of the phenomenon. The proposed concept of variable bandwidth at a THz frequency in the SSPP structure has been demonstrated through Co-EM simulation. For the experimental validation of the proposed approach, the filter has been designed at microwave frequency, developed on a 60 mil (1.52 mm) thick microwave laminate, and characterized using a Keysight Field-Fox analyzer N9918A. In THz and microwave frequency regime, the designed filter has 3-dB BW reconfigurability of 20 GHz (0.41–0.43 THz) and 300 MHz (100–400 MHz) with the insertion loss of ~3 dB and ~1.7 dB–3.2 dB, respectively. The proposed reconfigurable bandpass filter will have an important role in the design and development of plasmonic circuits and systems. [ABSTRACT FROM AUTHOR]

In this paper, a new time-domain (TD) solution is proposed for corner diffraction by finite-edge flat plate structures. First, TD solution is considered for corner amplitude diffraction by edges of a flat plate, and then for corner slope diffraction (CSD) which takes into account the finiteness of the plate edges. To show the significance of CSD, results have been shown for diffraction of ultra-wideband signals by edges of a horn antenna which is a structure made by interconnected flat plates. The comparison between the TD solution and the numerical inverse fast Fourier transform of the corresponding frequency-domain solution validates the proposed solution. Finally, the computation times of both methods have been compared. [ABSTRACT FROM AUTHOR]

This paper reports development, design, and analysis of designer (or spoof) surface plasmon polariton-based feeding configuration to excite a dual-band antenna. As an example, a planar transverse electric and magnetic horn antenna is designed and fed by the proposed transition structure. Designer surface plasmon polariton modes are supported by a metal surface at microwave frequency when it is corrugated with periodical grooves. An efficient transition for converting quasi-transverse electric and magnetic waves of microstrip line into spoof surface plasmon polariton (SSPP) waves has been designed in microwave frequency range using periodically corrugated metal strip. SSPP wave is confined at the teeth part of the corrugation. Simulated and measured reflection and transmission characteristics are in good agreement. The spoof SPP-fed dual-band antenna is designed, fabricated, and characterized in microwave anechoic chamber and measured results are coincident with simulated results. [ABSTRACT FROM AUTHOR]