Department of Electrical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Though the advantages of direct Matrix-based Dual-Active-Bridge (MB-DAB) converters have been highlighted in recent literature, their complete set of modulation possibilities are yet to be analyzed. This holistic study of modulation modes is presented in the paper, which divulges the power transfer boundaries of possible modulation modes in the front-end half-bridge (FE-HB) and front-end full-bridge (FE-FB) MB-DABs, and highlights the acceptable modulation scheme(s). For an optimally designed 1 MVA modular MVAC-LVDC conversion stage of Solid-State-Transformer (SST), the FE-HB MB-DAB configuration proves to be a better alternative compared to FE-FB variant in terms of the power transfer boundaries, apart from the other topology related benefits highlighted in literature. Simulation results for modulation of the full-scale 1 MVA SST's 35.1 kW(pk) submodules validate the mathematical analysis. Further, a scaled-down 1.4 kW(pk) experimental validation verifies the FE-HB MB-DAB converter's working principle.

World University root node

Modulation of Direct Matrix-Based Dual-Active-Bridge (MB-DAB) AC-DC Converters

This paper presents a new compact ultra-thin triple-band absorber which shows near-unity absorption in C, X and Ku-bands. It consists of an inductive stub loaded circular ring resonator and a flower-shaped resonating patch on top of 0.8 mm thin FR-4 grounded dielectric substrate. A transmission line equivalent is proposed, and circuit simulation response is in good agreement with the full-wave analysis. The unit-cell architect's 4fold symmetry makes it polarisation-insensitive for different polarisation angles in the azimuthal plane (= 0°) under normal incidence. Its good shows angular stability up to 45° under TE (75° under TM) incidences for all three frequencies. Surface current patterns are analysed at resonant frequencies to illustrate the mechanism behind the electromagnetic absorption. This design's novelty lies in the centre patch's dual-resonating behaviour, making this design compacted one. The absorber has low-profile nature with cell periodicity of 0.163λL and thickness 0.013λL, where λL is the lowest resonating peak wavelength. An X-band conventional MSA is fabricated on a thin FR-4 substrate. In-band RCS reduction (nearly 18 dBsm) of the antenna is verified after loading with the proposed absorber. The absorptivity peaks are optimised such that the same structure would be used in different applications like RF energy harvesting, RCS reduction and sensor applications. © 2021 Wiley Periodicals LLC.

International Journal of RF and Microwave Computer-Aided Engineering

Compact polarisation insensitive wide angular stable triple band absorber for RF energy harvesting, RCS reduction, and sensor applications

This work describes an Ultra-Wideband (UWB) antipodal antenna utilized for the microwave imaging of a breast phantom. The designed antenna consists of stubs arraged at a particular length apart to widen the bandwidth and an elliptical patch at the aperture of the structure is placed to improve the performance at high frequencies. The proposed antenna achieves a bandwidth from 1.3 GHz to around 14 GHz with good impedance matching as well. The designed antenna attains a peak gain of 10 dBi at 6 GHz and the proposed structure is utilized for the monostatic microwave imaging of the breast with two tumors using Synthetic Aperture Radar. © 2021 IEEE.

2020 IEEE MTT-S Latin America Microwave Conference (LAMC 2020)

Microwave Breast Imaging using Synthetic Aperture Radar Method utilizing UWB Antenna

This paper presents a new compact unit cell for reflection-type linear co to cross-polarization conversion. The metasurface is printed on a perfect conductor-backed dielectric substrate. The unit cell consists of double E-shaped resonators. The structure exhibits a broadband linear cross conversion from 6.46 - 14.07 GHz (7.61 GHz or 74.2 %) with a polarization conversion ratio (PCR) is &gt; 90 %. The converter response is found to be stable at a high incidence angle of &gt; 30°. Periodicity of the unit cell is 0.38 λ 0 , where λ 0 is the free space wavelength at the center frequency of the operating range. This proposed converter can be used for stealth technology for radar cross-section (RCS) reduction. At frequency 9.8 GHz, the 4 x 4 array of the converter reduces the RCS by more than 21 dB for both monostatic and bistatic conditions.

IEEE Xplore

Double E-Shaped Reflection Type Polarization Converter For Radar Cross Section Reduction

In this work, radio frequency (RF) micro-electromechanical system (MEMS)-based frequency and bandwidth tunable bandpass filter is presented for application in 24 GHz Doppler radar transceivers. The filter is fabricated on 635 μm alumina substrate using surface micromachining process. Total area of the filter is only 2.8 mm2 excluding bias lines and pads. Functional building blocks of the proposed filter are fabricated and tested independently to ensure optimum filter responses. The proposed filter can be tuned to any frequency between 22 and 24 GHz based on electrostatic actuations. It demonstrates insertion loss of 1.67 dB and matching of 18.6 dB at 24 GHz with fractional bandwidth of 6.5%. Filter gives acceptable matching over a 5 GHz bandwidth (21.65-26.65 GHz) with an average insertion loss of 4.7 dB. Filter works satisfactorily up to 10 billion cycles with 0.1 to 1 W of RF power. To the best of our knowledge, this is the first reported tunable MEMS bandpass filter at 24 GHz with 10 billion cycles reliability and with 1 W of RF power for radar applications. © 2021 Wiley Periodicals LLC.

Frequency and bandwidth tunable reliable MEMS bandpass filter for 24 GHz radar applications

This paper proposes a hybrid decoupling method based on a novel electromagnetic bandgap (EBG) structure and hair-pin shaped defected ground structure (DGS) to obtain high isolation between 2-element multiple input multiple output (MIMO) antenna at 5G millimeter wave band over 27.5-28.35$ GHz. The proposed EBG designed on stacked dielectric substrates, achieves a wide frequency band-gap between 26.2-32.03 GHz (20 %). A 2 × 3 array of the EBG is arranged between two electromagnetically coupled radiating patches in order to suppress the surface wave coupling. Substrate integrated waveguide (SIW) feeding network and cavity are strategically incorporated in the antenna design for improving the radiation performance and minimizing the losses from the feed. EBG shows an average isolation improvement of 13.9 dB within 5G band as compared to unloaded MIMO antenna. The additional reduction in coupling is achieved by placing hair-pin DGS (HP-DGS) on the ground plane, resulting in maximum isolation improvement of 47.7 dB at 27.94 GHz. The prototype of the MIMO was fabricated and experimentally verified. Measured peak isolation between the antennas is obtained as 71.9 dB, having a gain of 9 dBi and front to back ratio (FTBR) of 19.8 dB. A good diversity performance is also noticed for the designed MIMO with envelope correlation coefficient (ECC) of 0.00015, diversity gain (DG) of 9.99, and channel capacity loss (CCL) of 0.025 bits/Hz/sec. Later, SIW corporate feed network is designed for 4-element linear array loaded with EBG and HP-DGS to achieve higher gain and narrow beamwidth. The array was fabricated and the measured results are found in good accordance with the simulation results. The peak gain, beamwidth, and FTBR of the array are 13.3 dBi, 16.2°, and 19.97 dB respectively. © 2021 IEEE.

Fulltext

IEEE Access

Isolation Improvement of MIMO Antenna Using Novel EBG and Hair-Pin Shaped DGS at 5G Millimeter Wave Band

IEEE Transactions on Electron Devices

2020 Index IEEE Transactions on Electron Devices Vol. 67

The COVID-19 pandemic has accelerated the need for automatic triaging and summarization of ultrasound videos for fast access to pathologically relevant information in the Emergency Department and lowering resource requirements for telemedicine. In this work, a PyTorch based unsupervised reinforcement learning methodology which incorporates multi feature fusion to output classification labels, segmentation maps and summary videos for lung ultrasound is presented. The use of unsupervised training eliminates tedious manual labeling of key-frames by clinicians opening new frontiers in scalability in training using unlabeled or weakly labeled data. Our approach was benchmarked against expert clinicians from different geographies displaying superior Precision and F1 scores (over 80% and 44%).

Software Impacts

vid-SAMGRAH: A PyTorch framework for multi-latent space reinforcement learning driven video summarization in ultrasound imaging

Localized plasmon resonance in metallic nanoparticles can enable polarization-dependent electric field enhancement. Semiconducting monolayers are used in conjunction with polarization-sensitive plasmonic structures, to maximize the field overlap and promote polarization-sensitive photon detection. © OSA 2021, © 2021 The Author(s)

Optics InfoBase Conference Papers

Polarization sensitive photodetection using semiconducting monolayers

Objective: This paper presents a simple automated method to estimate respiration rate (RR) from the photoplethysmography (PPG) signals. Methods: The method consists of preprocessing, extremely low-frequency two-pole digital resonator, fast Fourier transform, spectral magnitude computation, prominent spectral peak identification and respiration rate computation. Validation Dataset: The proposed RR estimation method is evaluated using standard PPG databases including MIMIC-II and CapnoBase. Results: The proposed method had estimation accuracy with absolute error value (median, 25th–75th percentiles) of 0.522 (0, 1.403) and 0.2746 (0, 0.475) breaths/minute for the PPG recordings from the MIMIC-II and CapnoBase databases, respectively for the 30 s segment. Results showed that the proposed method outperforms the existing methods such as the empirical mode decomposition and principal component analysis (EMD-PCA), ensemble EMD-PCA, and improved complete EEMD with adaptive noise-PCA methods. Conclusion: Results demonstrate that the proposed method is more accurate in estimating RR with less processing time of 0.0296 s as compared to that of the existing methods. This study further demonstrate that the two-pole digital resonator with extremely low-frequency can be simple method to estimate the RR from the PPG signals. © 2020, Springer Nature Singapore Pte Ltd.