SUMMARYA methodology for designing FIR multi notch filters (NFs) derived from second-order prototype IIR NFs is suggested. Rejection bandwidth for the designed filter can be controlled by suitable choice of 'r ', the pole radius of the IIR prototype NFs. The suggested multi NF can also be adapted to eliminate second-, third-and fourth-order harmonics of periodic noise besides the fundamental noise frequency component. A special case when two notch frequencies 1 and 2 are such that [(cos 1 )(cos 2 ) = −1/2] has also been discussed. The IIR multi NF design for this special case results in reduction of the number of multipliers without affecting the response of the desired NF. For the aforereferred condition, the required coefficients of impulse response of FIR multi notch filter get reduced to almost half in number resulting in reduced computations. The number of zero coefficients further reduces with increase in 'r ' value. In addition, the frequency response becomes better, with reduced ripples in the pass bands, when 'r ' is increased and length 'L' of the FIR NF is chosen appropriately.
This paper presents the design of a wideband Balun for Archimedean spiral antenna. The Balun is designed with a microstrip Line (MSL) to parallel stripline (PSL) transition which is used as a balanced feed for Archimedean spiral antenna. This transition Balun has the wideband performance of 194% over the band of 0.5GHz to 18.5 GHz. The back-to-back MSL to PSL has a return loss of better than 15dB over the band of operation. The performance of the Balun was validated with the spiral antenna. The measured results were compared with the simulated results and it shows that the Balun operates well over wideband frequency range. The Balun is designed and fabricated using the commonly available FR4 substrate with permittivity of 4.2. The designs have been simulated and optimized using 3D Electromagnetic Solver CST Microwave Studio.
A methodology for designing FIR bi notch filters derived from second order prototype IIR notch filters is suggested. A special case when two notch frequencies ω 1 and ω 2 are such that [(cos ω 1 )(cos ω 2 ) = -1/2] has been discussed. The IIR bi notch filter design for this special case results reduction in the number of multipliers without affecting the response of the desired notch filter. For the referred condition, the required design weights of FIR bi notch filter reduce to almost half in number resulting in reduced computations.
Real time monitoring of high voltage devices in smart grid is implemented using wireless sensors. They ensure reliable power transfer and avoid cascading power failures. Powering these sensors remotely is a challenge. This paper presents a novel method of powering sensors remotely using magnetic field harvester. A dumbbell shaped magnetic core is designed and optimized to harvest magnetic field near high voltage bus bars/transformers in electrical substation. The harvested power is rectified and boosted. Impedance matching circuit is designed to obtain maximum power transfer to the wireless sensor. The energy thus harvested is used to power wireless sensors and make them self sustainable. The experimental results show that the proposed core with 40,000 turns can harvest 17.6 mW of output power when placed in magnetic flux density of 9 µTrms.
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