Data Analysis and Validation of Acquired Temperature Data on Underwater Platform

Underwater missiles are launched from canister by hot gasses produced by a gas generator. Hot gasses eject the missile out of canister, positioned on an underwater platform in high seas at a depth of 50 m to 70 m. During development phase of submarine launched missile, maximum number of physical parameters related to platform and launching mechanism are acquired on a data acquisition system on-board platform and selected critical parameters are transmitted to control station in real time through an optical data communication link. Missile parameters are recorded on-board and transmitted to the control station by delayed transmission technique once the missile is out of water. Exit velocity of missile is very important parameter for the missile trajectory and range, which depends upon the heat loss in canister and annular gap pressure between missile and canister during the ejection process. Prediction of exit velocity is validated by heat loss calculation by measured temperature at different stations during the test. Temperature measurement is carried out by sensors mounted on the inner wall of canister and also by jumping type of temperature sensor, which measures canister gas temperature. In spite of all efforts, few sensors do not work as expected. It is important to measure various parameters according to instrumentation measurement plan. In case of temperature measurement, sometimes, it is required to predict temperature at location, where sensor was originally not mounted. To validate the recorded test data, another set of data is needed for which one has to wait till next test is conducted that may take years and practically impossible to ensure identical test setup and environmental condition. A mathematical approach to predict temperature at required location and to validate the recorded test data is presented. 

A Coplanar Waveguide Fed Rectangular Reconfigurable Patch Antenna with Switchable Strips for Polarization Diversity

A compact single feed rectangular patch antenna with reconfigurable circular polarization has been proposed in this paper. The basic antenna structure is a rectangular patch of dimensions 10 mm x 15 mm printed on a thin FR4 substrate of thickness 3 mm. Two rectangular strips are connected through switches at sideways of the main patch to get polarization diversity. The polarization of the proposed antenna can be reconfigured between left hand circular polarization (LHCP) and right hand circular polarization (RHCP) by the current path, which is changed by operating the switches in ON and OFF modes. The antenna is designed and simulated using IE3D MoM based electromagnetic simulator. The simulated results show good return loss, radiation pattern, axial ratio and acceptable gain at the operating frequency. The antenna has around 15 % effective impedance bandwidth over 4.0 GHz - 4.8 GHz frequency band at a maximum gain of 3.0 dBi with polarization diversity.Defence Science Journal, Vol. 64, No. 1, January 2014, DOI:10.14429/dsj.64.480

A Study on Utilization of Polarimetric SAR Data in Planning a Smart City

AbstractIn the present world, there is a huge requirement for a truly efficient city not only operating in an integrated mode, but also to optimize the resources of each system to have better eco-friendly livelihood. Currently, this novel concept has led to the establishment of smart city with integration among informational and operational efficiency. With recent advances in remote sensing especially in the field of Polarimetric Synthetic Aperture Radar (SAR) data, using suitable polarimetric target decomposition techniques, data can be classified for further utilization in remote sensing applications. As a part of this exploration, a study has been taken to understand the utilisation of polarimetric data in building a smart city by exploiting the available resources in a given urban area. Different types of polarimetric decomposition techniques are applied on the data along with polarimetric speckle filters where classification of targets is performed based on the scattering mechanism of the polarized wave with each target in the scene. Encouraging preliminary results were obtained in the study using polarimetric SAR data adding another dimension in planning a smart city

Robust, Efficient and Low Profile Fractal Enabled EBG Incorporated Wearable Antenna for WLAN Standards

A compact, robust Koch fractal combined triangular monopole antenna incorporated with a Sierpinski fractal EBG unit cell array is proposed for integral solutions of wearable devices in WLAN standards. The fractal enabled EBG-Antenna has a modified triangular microstrip that acts as a radiator and a 2X2 array of Sierpinski square EBG unit cells as a reflective surface to enhance the performance also as a shield linking the antenna and human body. The proposed antenna demonstrations and impedance match bandwidth of 32 MHz, a gain of 7.86 dBi, Front to back ratio of 13 dB, Radiation Efficiency of 90.35 % at 2.45 GHz in free space. The EBG-Antenna performs well under different bending conditions and human tissue loading as verified by measurements. The specific absorption rate (SAR) is also evaluated and found within limits as per standards. The computed results accomplished the SAR of 0.302 W/Kg, 0.1423 W/Kg for 1 g, 10 g of tissue, respectively, which demonstrates about a 95 % drop associated with the antenna without EBG. Furthermore, the fractal loading makes the antenna compact; EBG introduced at the underside of the monopole antenna gives a high gain-bandwidth product and disengages the human body and the antenna, making the realized antenna a potential candidate with possible seamless incorporation of specified wearable applications in WLAN standards

Dual-Band, EBG-DGS Wearable Antenna for Emergency Services and Responses in WBAN

The paper introduces a compact, thin flexible textile antenna integrated with an Electromagnetic Bandgap (EBG) and Defected Ground Structure (DGS) covering the Wireless Local Area Networks (WLAN) bands (2.4-2.485 GHz and 5.1-5.9 GHz) for emergency services and responses. The geometry and configuration of the proposed antenna are made from common clothing jeans fabric, which makes the antenna more flexible, thin, and conformal. A new configuration of EBG structure is developed using Minkowski fractal geometry as base geometry and a DGS with the complementary dumbbell-shaped slot to operate in WLAN standards. The EBG structure is used to isolate the antenna from the human body, whereas the DGS is used to improve the bandwidth and polarization purity. The prototype covers the WLAN bands with gains of 3.37 dBi and 6.47 dBi, a bandwidth of 115.9 MHz, and 398.06 MHz for the specified wireless bands. The integrated antenna demonstrates a Front to Back Ratio (FBR) of 16.77 dB and 32.72 dB, the radiation efficiency of 36.9 % and 73.8 %, and a better cross-polarization level at 2.45 GHz, 5.85 GHz, respectively. The antenna shows a high gain and an efficiency of about 70 % under the various bending scenario. Thus, the anticipated antenna is the most appropriate and potential candidate for wearable applications in various domains