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Kumar C.,Communication Systems Group | Guha D.,University of Calcutta
IEEE Transactions on Antennas and Propagation | Year: 2012

Experiments with probe-fed circular patches using conventional and defected ground planes flashed some interesting features relating to cross-polarized (XP) electric fields and associated radiations before the present authors. Those led to a series of new investigations for understanding the nature of XP fields and to deal with them using defected ground structure (DGS) for improved XP performance. In the first phase of investigation, the XP radiations of a probe-fed circular patch with conventional ground plane have been critically studied as a function of the radial probe location. Remarkably significant effect is experimentally demonstrated. New information about orthogonal resonant fields and its importance in designing an antenna is provided. In the second phase of investigation, limitations of dot-shaped DGS in reducing XP level are experimentally studied. As its improved variants, two new DGS geometries such as annular ring and circular arcs have been explored. The arc-DGS appears to be highly efficient in terms of suppressing XP fields. Suppression by 10-12 dB has been experimentally demonstrated. Each design has been experimented in both C- and X-bands to earn confidence on the measured data. © 2006 IEEE. Source


Guha D.,University of Calcutta | Banerjee A.,University of Calcutta | Kumar C.,Communication Systems Group
IEEE Transactions on Antennas and Propagation | Year: 2012

A resonant mode (HEM 12δ), other than those (HEM 11δ and TM 01δ) conventionally excited and used in a cylindrical dielectric resonator antenna (CDRA) has been examined with a view for using it as another radiating mode with broadside radiation patterns. Excitation of the mode, being the most challenging aspect, has been discussed and resolved by employing an innovative technique. The proposed concept has been successfully verified and experimentally demonstrated for the first time. More than 8-dBi peak gain with excellent broadside radiation has been obtained from a prototype shaped from a commercially available low-loss dielectric material with relative permittivity 10. © 2006 IEEE. Source


Guha D.,University of Calcutta | Gajera H.,University of Calcutta | Kumar C.,Communication Systems Group
IEEE Transactions on Antennas and Propagation | Year: 2015

In this communication, cross-polarized (XP) radiation of cylindrical dielectric resonator antenna (CDRA) has been investigated with a view to identify the source of the same. The study starts with a conjecture, which has been established through a systematic study using simulated results. The inference has been verified experimentally with the help of a set of prototypes. HEM21δ has been identified as the XP generating mode and a small metallic grounded post of circular cross section has been conceived to perturb the same to prove the conjecture. This insight has been extended to demonstrate a practical application indicating a possibility of achieving up to 8-10-dB suppression in XP radiation from a CDRA. © 1963-2012 IEEE. Source


Guha D.,University of Calcutta | Banerjee A.,University of Calcutta | Kumar C.,Communication Systems Group | Antar Y.M.M.,Royal Military College of Canada
IEEE Antennas and Wireless Propagation Letters | Year: 2014

Higher-order {\rm HEM}12 \deltamode has been experimentally realized in a cylindrical dielectric resonator antenna (CDRA) very recently revealing broadside radiation like the dominant {\rm HEM}11 \deltamode. The primary challenge is the excitation of the mode in a practical DRA sitting on a metal ground plane, which was first resolved by introducing a floating feed as an equivalent current ribbon. In this letter, yet another technique has been explored using a conventional probe-fed CDRA placed on a metal plate. Only a new trough-shaped air cavity has been introduced in the ground plane just beneath the DRA to simulate a special boundary condition, which enunciates desired modal fields. Such a technique may be improvised for other potential applications. The proposed concept has been verified using both simulated and experimental results. © 2002-2011 IEEE. Source


Biswas S.,Institute of Technology and Marine Engineering | Guha D.,University of Calcutta | Kumar C.,Communication Systems Group
IEEE Transactions on Antennas and Propagation | Year: 2013

Controlling higher order modes up to third harmonic of the fundamental operating frequency in a microstrip line-fed patch antenna has been successfully demonstrated. Harmonic rejection in the antenna has been achieved at its feed level using highly compact design of defected ground structure (DGS). Rejection characteristics have been improved adding an open stub to the feed line. All possible higher order modes occurring in between the fundamental and the 3rd harmonic have been identified. Relative suppression of radiated fields with and without DGS-control has been quantitatively measured and effective control of harmonics has been experimentally ensured. The area occupied by the proposed DGS has been compared with earlier designs and over 40-90% reduction in size has been documented. © 2013 IEEE. Source

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