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Deshmukh A.,D.J.Sanghvi College of Engineering | Ray K.P.,Society for Applied Microwave Electronics Engineering and Research
IEEE Antennas and Propagation Magazine | Year: 2015

A very popularly used technique to realize broadband and compact microstrip antenna (MSA) is by cutting a slot at an appropriate position inside the patch. More frequently, U-slot and its variation, a half U-slot, have been used to increase the bandwidth (BW). In most of the available literature on U-slot cut antennas, a detailed explanation for broadband response due to U-slot has not been reported. In this paper, an extensive study for the broadband behavior for U-slot, half U-slot and double U-slot cut rectangular MSAs (RMSAs) is presented. The U-slot configurations with different aspect ratios (i.e., length-to-width ratio) for patch and slot dimensions have been studied. In U-slot and half U-slot cut patches, it has been observed that slot does not introduce any additional mode, but it modifies the fundamental and higher order mode resonance frequencies of the patch to yield broadband response. The slot also modifies surface current distribution at higher order mode to yield broadside radiation pattern characteristics over the complete BW, without any variations in the directions of principle planes. Further, in double U-slot cut RMSA, the second U-slot optimizes the impedance and frequency at modified higher order TM21 mode and, along with modified TM01 and TM20 modes, yields increase in the BW. This paper will give an insight into the functioning of U-slot cut antennas. © 1990-2011 IEEE. Source

Bhatnagar A.,Society for Applied Microwave Electronics Engineering and Research
International Journal of Microwave and Optical Technology | Year: 2014

Near field reflectance and transmission measurement (NFRTM) using lensed fiber probe has been demonstrated for two dimensional refractive index profiling (RIP) of optical fiber and simultaneous mode field profiling (MFP). The method is a modified version of confocal microscope based reflectivity measurement technique and employs all fiber optic components in the measurement setup. Commercially available telecommunication grade fiber optic components are used for demonstration of this method. The use of lensed fiber probe instead of microscope objective makes the measurement setup compact and reliable. The advantage of reported method lies in single step measurement of refractive index profile of fiber under investigation and also its mode profile. Measured values of these parameters for single mode, multimode and photonic crystal fiber compare quite well with reported results. Further work is being carried out to improve the NFRTM method for achieving higher accuracy in measured parameters. Source

Shirude N.,University of Mumbai | Pinto R.P.,Society for Applied Microwave Electronics Engineering and Research | Panse M.S.,University of Mumbai
International Conference on Communication and Signal Processing, ICCSP 2014 - Proceedings | Year: 2014

RADAR (Radio Wave Detection And Ranging) systems are widely used now days for detecting a target, obtaining its location along with direction and velocity of detected object. Most challenging part in RADAR system is to getting better accuracy and resolution. In this paper, we have designed a radar transmitter and receiver using direct sequence spread spectrum for improving range accuracy. Spread spectrum modulation technique has been chosen as it has some inherent merits like accuracy of ranging, sensitivity of power estimation, interference suppression etc. © 2014 IEEE. Source

Goswami H.,Gauhati University | Devi M.,Gauhati University | Rambabu S.,Society for Applied Microwave Electronics Engineering and Research | Barbara A.K.,Gauhati University | Prakash K.,Gauhati University
Indian Journal of Radio and Space Physics | Year: 2014

The paper aims to examine the relation between rainfall anomalies and occurrence of earthquakes (magnitude > 6.5) in the Indian region. For this purpose, earthquakes of Sikkim (18 September 2011), Gujarat (26 January 2001), Uttarkashi (20 October 1991) and Assam (15 August 1950) are considered. Anomaly in rainfall magnitude is calculated from the synoptic seasonal fluctuation of rainfall as the seasonal ambient level, considering gridded rainfall data from India Meteorological Department (IMD) (1°×1°), NECP/NCAR reanalysis (2.5°×2.5°), and monthly accumulated rainfall data from the Indian Institute of Tropical Meteorology (IITM). Monthly spatial rainfall distribution obtained from Tropical Rainfall Measuring Mission (TRMM) is also plotted over the epicenter zone of the earthquakes under consideration. In Sikkim, Gujarat and Assam earthquake cases, high positive anomaly (beyond ambient level) in rainfall is observed in the earthquake months, whereas no such association is detected for Uttarkashi event. Further, the rainfall anomalies are associated with earthquake induced heat flux and the results obtained are discussed in terms of the seasonal atmospheric variabilities and geographical features of the region near to earthquake epicenter. Source

Iwashita T.,High Energy Accelerator Research Organization | Adachi T.,High Energy Accelerator Research Organization | Arai T.,High Energy Accelerator Research Organization | Arakida Y.,High Energy Accelerator Research Organization | And 7 more authors.
IPAC 2010 - 1st International Particle Accelerator Conference | Year: 2010

The KEK PS-Booster which had finished thirty years of operation in 2006 is currently under renovation as a digital accelerator (DA) [1]. The first plan of us is to accelrate an argon ion beam using the induction accleration system which was developed at KEK [2]. The acceleration devices is described and the acceleration scenario in a case of Ar8+ is given in details. For the induction acceleration, beam bunch monitors and frontend processors is crucial devices to pick up information of the circulating beam timing with accuracy. R&D works of those components are discussed. Source

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