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Papers by nishant kumar
2015 International Conference on Communications and Signal Processing (ICCSP), 2015
An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical diele... more An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical dielectric resonator antenna (DRA) is presented for cognitive radio applications. The proposed antenna is a combination of semicircular-semi hexagon shape microstrip patch, which is fed by coplanar waveguide (CPW). The dielectric resonator antenna (DRA) is cylindrical in shape excited by a microstrip slot fed on the rear side which shows a narrow band (NB) characteristics. The microstrip antenna provides a wide bandwidth operates from 2.58 GHz to 14 GHz. The DRA provides a narrow bandwidth operates from 10.07 GHz to 11.38 GHz. The UWB antenna is used for sensing the spectrum and the narrow-band DRA used for communication operation. A very good isolation between the two antenna ports (S 21 less than-15 dB) are also achieved. Compared to the existing designs the peak gain of the antenna is highly increased around 6.15 dB. Index Terms-Cognitive radio, coplanar waveguide, dielectric resonator antenna (DRA), ultra-wideband.
2015 International Conference on Communications and Signal Processing (ICCSP), 2015
An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical diele... more An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical dielectric resonator antenna (DRA) is presented for cognitive radio applications. The proposed antenna is a combination of semicircular-semi hexagon shape microstrip patch, which is fed by coplanar waveguide (CPW). The dielectric resonator antenna (DRA) is cylindrical in shape excited by a microstrip slot fed on the rear side which shows a narrow band (NB) characteristics. The microstrip antenna provides a wide bandwidth operates from 2.58 GHz to 14 GHz. The DRA provides a narrow bandwidth operates from 10.07 GHz to 11.38 GHz. The UWB antenna is used for sensing the spectrum and the narrow-band DRA used for communication operation. A very good isolation between the two antenna ports (S 21 less than -15 dB) are also achieved. Compared to the existing designs the peak gain of the antenna is highly increased around 6.15 dB.
In this paper a dual port microstrip antenna with tunable band pass filter is proposed for cognit... more In this paper a dual port microstrip antenna with tunable band pass filter is proposed for cognitive radio applications. In single port reconfigurable antennas for cognitive radio, sensing and communication is done simultaneously. This can lead to failure of real time communication, also it may induce interference to primary user, dual antenna system solves this problem. The proposed antenna consist of one UWB microstrip antenna for sensing the holes in spectrum and other is communication antenna. Communication antenna is made tunable by using varacter diode in 'G' shaped DMS(defected microstrip structure) filter integrated in feedline.The sensing antenna is having UWB bandwidth from 3.4 GHz to 13.2 GHz and efficiency of more than 80%. The narrowband antenna has dual and triple operating frequencies which is tunable in the range of 4-5 GHz, 6-10 GHz and 10-11 GHz according to the biasing of varacterdiode. This antenna as efficiency more than 70%.. KEYWORDS: ultra wideband (UWB) antenna, Defected microstripstructure (DMS), Tunable filter,varacter diode
Equivalent circuits of electromagnetic devices are an efficient alternative to full transient EM ... more Equivalent circuits of electromagnetic devices are an efficient alternative to full transient EM analysis especially when phenomenon such as inrush currents are investigated. The time-constants in such cases generally, for a 50 Hz transformer, are in the order of several minutes hence rendering full transient EM simulation time consuming. On the circuit level, the simulation time involved is a fraction of the EM transient case. Furthermore, parametric analysis may take place in the circuit simulation allowing what-if scenarios to be tested e.g. effect of system impedance on inrush behaviour.This article shows the application of the CST EM STUDIO® (CST EMS) Magnetostatic solvers within the System and Assembly Modeling (SAM) framework to the emulation of two standard transformer tests for the extraction of T-equivalent circuit parameters at 50 Hz.
Conference Presentations by nishant kumar
— An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow–band cylindrical die... more — An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow–band cylindrical dielectric resonator antenna (DRA) is presented for cognitive radio applications. The proposed antenna is a combination of semicircular-semi hexagon shape microstrip patch, which is fed by coplanar waveguide (CPW). The dielectric resonator antenna (DRA) is cylindrical in shape excited by a microstrip slot fed on the rear side which shows a narrow band (NB) characteristics. The microstrip antenna provides a wide bandwidth operates from 2.58 GHz to 14 GHz. The DRA provides a narrow bandwidth operates from 10.07 GHz to 11.38 GHz. The UWB antenna is used for sensing the spectrum and the narrow-band DRA used for communication operation. A very good isolation between the two antenna ports (S 21 less than-15 dB) are also achieved. Compared to the existing designs the peak gain of the antenna is highly increased around 6.15 dB. Index Terms— Cognitive radio, coplanar waveguide, dielectric resonator antenna (DRA), ultra-wideband.
— This paper presents a selective frequency reconfigurable antenna, suitable for cognitive radio ... more — This paper presents a selective frequency reconfigurable antenna, suitable for cognitive radio applications. Reconfigurability is achieved by inserting PIN diode switches in DMS(defected microstrip structure) 'T' slot filter. The proposed antenna is capable of switching between a wide operating band of 3.0 GHz – 10 GHz and six different narrow band operating from 5 GHz to 10 GHz. UWB case is used for sensing the entire band and then adjusting its bandwidth to select the suitable sub-band and pre-filter out the other ones to communicate with wireless devices without interference with others. The proposed antenna patch is a combination of two semi-circular patches. For each case reflection coefficient is calculated, it maintains less than-10 dB throughout the operating frequency. Radiation Patterns for each case also reveal a very low distortion as required. Gain is more than 70% in each case. Index Terms— Cognitive radio, frequency-reconfigurable antenna,P-in diode switches, wideband-to-sub-bands reconfiguration, defected microstrip structure.
—A novel UWB antenna is consisting of elliptical structure with symmetrical slots which performs ... more —A novel UWB antenna is consisting of elliptical structure with symmetrical slots which performs over Ultrawideband (UWB), an antenna with high isolation over-25dB throughout the entire band. The proposed structure is designedon an FR4 substrate with dimensions of 23mm X 38mm X 1.6mm. The configuration of antenna is designed for high isolation with reflector element on the ground plane over the entire UWBband. The proposed design also exhibits 2:1 VSWR impedance Bandwidth over the UWB band.
2015 International Conference on Communications and Signal Processing (ICCSP), 2015
An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical diele... more An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical dielectric resonator antenna (DRA) is presented for cognitive radio applications. The proposed antenna is a combination of semicircular-semi hexagon shape microstrip patch, which is fed by coplanar waveguide (CPW). The dielectric resonator antenna (DRA) is cylindrical in shape excited by a microstrip slot fed on the rear side which shows a narrow band (NB) characteristics. The microstrip antenna provides a wide bandwidth operates from 2.58 GHz to 14 GHz. The DRA provides a narrow bandwidth operates from 10.07 GHz to 11.38 GHz. The UWB antenna is used for sensing the spectrum and the narrow-band DRA used for communication operation. A very good isolation between the two antenna ports (S 21 less than-15 dB) are also achieved. Compared to the existing designs the peak gain of the antenna is highly increased around 6.15 dB. Index Terms-Cognitive radio, coplanar waveguide, dielectric resonator antenna (DRA), ultra-wideband.
2015 International Conference on Communications and Signal Processing (ICCSP), 2015
An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical diele... more An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow-band cylindrical dielectric resonator antenna (DRA) is presented for cognitive radio applications. The proposed antenna is a combination of semicircular-semi hexagon shape microstrip patch, which is fed by coplanar waveguide (CPW). The dielectric resonator antenna (DRA) is cylindrical in shape excited by a microstrip slot fed on the rear side which shows a narrow band (NB) characteristics. The microstrip antenna provides a wide bandwidth operates from 2.58 GHz to 14 GHz. The DRA provides a narrow bandwidth operates from 10.07 GHz to 11.38 GHz. The UWB antenna is used for sensing the spectrum and the narrow-band DRA used for communication operation. A very good isolation between the two antenna ports (S 21 less than -15 dB) are also achieved. Compared to the existing designs the peak gain of the antenna is highly increased around 6.15 dB.
In this paper a dual port microstrip antenna with tunable band pass filter is proposed for cognit... more In this paper a dual port microstrip antenna with tunable band pass filter is proposed for cognitive radio applications. In single port reconfigurable antennas for cognitive radio, sensing and communication is done simultaneously. This can lead to failure of real time communication, also it may induce interference to primary user, dual antenna system solves this problem. The proposed antenna consist of one UWB microstrip antenna for sensing the holes in spectrum and other is communication antenna. Communication antenna is made tunable by using varacter diode in 'G' shaped DMS(defected microstrip structure) filter integrated in feedline.The sensing antenna is having UWB bandwidth from 3.4 GHz to 13.2 GHz and efficiency of more than 80%. The narrowband antenna has dual and triple operating frequencies which is tunable in the range of 4-5 GHz, 6-10 GHz and 10-11 GHz according to the biasing of varacterdiode. This antenna as efficiency more than 70%.. KEYWORDS: ultra wideband (UWB) antenna, Defected microstripstructure (DMS), Tunable filter,varacter diode
Equivalent circuits of electromagnetic devices are an efficient alternative to full transient EM ... more Equivalent circuits of electromagnetic devices are an efficient alternative to full transient EM analysis especially when phenomenon such as inrush currents are investigated. The time-constants in such cases generally, for a 50 Hz transformer, are in the order of several minutes hence rendering full transient EM simulation time consuming. On the circuit level, the simulation time involved is a fraction of the EM transient case. Furthermore, parametric analysis may take place in the circuit simulation allowing what-if scenarios to be tested e.g. effect of system impedance on inrush behaviour.This article shows the application of the CST EM STUDIO® (CST EMS) Magnetostatic solvers within the System and Assembly Modeling (SAM) framework to the emulation of two standard transformer tests for the extraction of T-equivalent circuit parameters at 50 Hz.
— An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow–band cylindrical die... more — An ultra-wideband (UWB) planar microstrip antenna integrated with a narrow–band cylindrical dielectric resonator antenna (DRA) is presented for cognitive radio applications. The proposed antenna is a combination of semicircular-semi hexagon shape microstrip patch, which is fed by coplanar waveguide (CPW). The dielectric resonator antenna (DRA) is cylindrical in shape excited by a microstrip slot fed on the rear side which shows a narrow band (NB) characteristics. The microstrip antenna provides a wide bandwidth operates from 2.58 GHz to 14 GHz. The DRA provides a narrow bandwidth operates from 10.07 GHz to 11.38 GHz. The UWB antenna is used for sensing the spectrum and the narrow-band DRA used for communication operation. A very good isolation between the two antenna ports (S 21 less than-15 dB) are also achieved. Compared to the existing designs the peak gain of the antenna is highly increased around 6.15 dB. Index Terms— Cognitive radio, coplanar waveguide, dielectric resonator antenna (DRA), ultra-wideband.
— This paper presents a selective frequency reconfigurable antenna, suitable for cognitive radio ... more — This paper presents a selective frequency reconfigurable antenna, suitable for cognitive radio applications. Reconfigurability is achieved by inserting PIN diode switches in DMS(defected microstrip structure) 'T' slot filter. The proposed antenna is capable of switching between a wide operating band of 3.0 GHz – 10 GHz and six different narrow band operating from 5 GHz to 10 GHz. UWB case is used for sensing the entire band and then adjusting its bandwidth to select the suitable sub-band and pre-filter out the other ones to communicate with wireless devices without interference with others. The proposed antenna patch is a combination of two semi-circular patches. For each case reflection coefficient is calculated, it maintains less than-10 dB throughout the operating frequency. Radiation Patterns for each case also reveal a very low distortion as required. Gain is more than 70% in each case. Index Terms— Cognitive radio, frequency-reconfigurable antenna,P-in diode switches, wideband-to-sub-bands reconfiguration, defected microstrip structure.
—A novel UWB antenna is consisting of elliptical structure with symmetrical slots which performs ... more —A novel UWB antenna is consisting of elliptical structure with symmetrical slots which performs over Ultrawideband (UWB), an antenna with high isolation over-25dB throughout the entire band. The proposed structure is designedon an FR4 substrate with dimensions of 23mm X 38mm X 1.6mm. The configuration of antenna is designed for high isolation with reflector element on the ground plane over the entire UWBband. The proposed design also exhibits 2:1 VSWR impedance Bandwidth over the UWB band.