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In this paper, we reported the wavelet analysis of lightning electric field of Narrow Bipolar Pulses (NBP) measured during two different monsoon season in Johor, Malaysia. The lightning electric field of NBP were divided into Narrow positive Bipolar Pulses (NPBP) and Narrow Negative Bipolar Pulses (NNBP). Analysis on the wavelet and frequency spectrum reveals that the energy spectrum for both NBPs...
Lightning generates electric fields are known to have negative consequences. In this study, two types of lightning electric fields which are Negative Return Stroke (NRS) and Narrow Bipolar Pulses were thoroughly analyzed using wavelet analysis. Hence, analysis on the wavelet and frequency spectrum reveal that the energy spectrum for NBP concentrates at high frequency (200 kHz to 500 kHz) with average...
Signals from collaborative beamforming (CB) nodes are always arriving out of phase at the intended receiver due to unsynchronized clock frequencies of different oscillators of these nodes. Beamforming nodes have to synchronize their carrier frequencies in order to eliminate any phase offset of the received signal. To do this, estimation, correction and prediction of phase offsets due largely to these...
This paper presents a method of collaborative beamforming (CB) of organizing sensor node location in linear array for wireless sensor network (WSN). Appropriate Appropriate selection of active CB nodes and cluster are needed each time to perform CB in WSNs. The nodes are modeled in linear array organization in order to perform as a perform as a linear antenna array (LAA). This newly proposed proposed...
In this paper, temporal characteristics of several initial electric field pulses of preliminary breakdown process (PBP) from very close negative cloud-to-ground (CG) flashes are compared to close narrow bipolar pulses (NBPs) to observe any similarity that may exists. Interestingly, we found that the initial PBP pulses are similar to close NBP with zero crossing time less than 5 µs, do not preceded...
This paper presents the investigation carried out on electrical near-field enhancement of a perturbation slit of a rectangular radiating nanostructure. The operating frequency is defined at thermal radiation spectrum from 20 THz to 40 THz. Single and two identical perturbation slits are introduced at the center of the nano structure. It was found that the former is able to enhance the near-field distribution...
Embedding fractal technology into an antenna provides desirable reduction of its physical size, as well as increasing its operating bandwidth and directivity. Nevertheless, the embedment of fractals is associated with proportionate increase of undesired harmonic problems associated with higher order modes of the antenna. In this paper, a microwave fractal dipole antenna that has tunable capability...
This article presents a novel method of optimizing sensor node location of wireless sensor network (WSN) in a circular arrangement. Appropriate selection of active collaborative beamforming (CB) nodes and cluster are needed each time to perform CB in WSNs. The nodes are modeled in circular array location in order to consider it as a circular antenna array (CAA). This newly proposed intelligent circular...
Recent developments in nano-technology have jumped from well established radiowave concept and analogy. Many designs have been proposed to investigate the capabilities of this high frequency regime. In this article, the dipole-patch nanoantenna has been designed based on effective wavelength scaling and equivalent radius concept. The square cross-sectional dimension has been adapted from circular...
This paper analyzes the interference of lightning flashes with wireless communication systems operating in the microwave band at 2.4 GHz. A bit error rate (BER) measurement method was used to evaluate BER during 3 heavy thunderstorms on January 25, March 17 and March 20, all in year 2011. In addition, BER measurements also were done on January 21 and March 30, 2011 under fair weather (FW) conditions...
Terahertz, THz, antennas have received much attention due to their capability to concentrate field energy and ability to support a wide range of applications such as energy collector and magnetic storage. In this paper, a rectangular patch antenna with perturbation slot is presented. The design is based on the Transmission-Line model. The dominant resonance shows good agreement at THz band with small...
This paper analyzes the effects of transient from lightning channel to wireless communication system operating in microwave band at 2.4 GHz. Received Signal Strength Indicator (RSSI) measurement method has been used to capture 3 lightning flashes (naked eyes method) with 7 spikes recorded at r distance from the lightning channel base with fixed d Transmitter-Receiver (T-R) separation at 1 meter. The...
The presence of harmonics are undesirable in many applications. Embedding fractal technology into an antenna makes it possible to reduce the physical size, increase its operating bandwidth and directivity. However, the technique can cause significant undesired harmonics problems associated with higher order modes of the antenna. This paper presents simulation and measurement work of a reduced size...
Designing a filter with harmonic suppression capability without adding any external filtering capacitors or notch filter is a big challenge. The paper presents the design of a compact microstrip bandpass filter having integrated harmonic suppression capability. The filter operates at a center frequency of 900 MHz. The structure chosen is the Hairpin Filter. The conventional hairpin is modified by...
Dual operation antennas have gained importance in the development of compact structures. In this paper, a simple approach using graphical approximations is presented for the design of a dual-band antenna. An example of dual-band operation is for the GPS (Global Positioning System) satellite reception with frequencies in the L-band. The chosen antenna is the rectangular microstrip patch having two...
This paper presents preliminary investigation and design of a rectangular nano-antenna that exhibits pentahertz (PHz) radiation. A plasmonic material is proposed as the substrate to be used for the antenna. The configuration chosen for the antenna radiating element is the rectangular structure. Numerical simulation based on FDTD has been performed on the designed antenna with varying substrate thickness...
Reduced size frequency reconfigurable fractal dipole antenna with harmonic suppression capability is presented in this paper. The proposed antenna consists of a narrow band radiating element, stub-filters and taper balun, producing harmonic suppression characteristics. In order to investigate the antenna performance, an extensive simulation (by CST and HFSS) and measurement works have been carried...
A novel approach which combines an adaptive linear antenna array and a non-linear function of particle swarm methodology has been developed to estimate the performance of antenna gain in the presence of sensor node geometry location uncertainties. The randomness of sensor nodes geometry location can produce higher energy consumption as it permits the generation of high peaks in radiation beampattern...
A recently introduce technique for improving cross-polarisation in microstrip antenna is to employ defected ground structure (DGS). In this paper, the experimental investigations have been carried out on a microstrip antenna that has been embedded with a DGS element having V-slot shape. It was found that the undesired cross-polarisation has been reduced while the impedance bandwidth has broadened.
IEEE 802.16m Multihop relay network is assiduously developing to accomplish high capacity services with large cell coverage. However due to lack of physical boundaries and injection of distributed relays, it is known to be more vulnerable to security holes as a trade off. In this paper we propose a new distributed authentication key scheme for Multihop Relays IEEE 802.16m network service. The propose...
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