A suspended dual band planar antenna based on a stepped-impedance structure modified to an array, loaded with Complementary Split-Ring Resonators (CSRRs), possessing good directivity pertaining point to point backhaul communication is acquainted. The presented antenna radiates at 2.4-2.5 GHz (4.4%) and 5.3-5.9 GHz (12%) with |S11| < −10 dB, accompanying directivity of 11.6 dBi and 11.3 dBi respectively. The antenna is loaded with CSRRs which works as a L-C tank resonator, to obtain better coupling, and to lower the frequency of radiation in 2.4 GHz band along with decreasing the return loss for both the bands of WLAN. The Suspended antenna, symmetrical across vertical axis, has four branches, each of which are obtained from Maximally Stepped-Impedance filter. A stable radiation pattern with high directivity in both the WLAN bands is achieved.

This study investigated the received signal strength and the propagation profiles for UHF channel 23, broadcast signal in Ondo State, Nigeria, at various elevation levels. The signal strength was measured quantitatively across the state along several routes with the aid of a digital field strength meter. A global positioning system (GPS) receiver was used to determine the elevation above ground level, the geographic coordinates and the line of sight of the various data points from the base station. Data obtained were used to plot the elevation and propagation profiles of the signal along measurement's routes. Results showed that the signal strength was strongest towards the northern parts with respect to distance compared to other routes with the same distance contrary to inverse square law. The threshold signal level for the station was 20dBµV which was recorded up to 50km line of sight from the transmitter towards the northern parts of the state where higher levels of elevation of data locations were recorded and 42km towards the southern parts with lower values of elevation. The propagation profiles for all the routes follow the elevation pattern of the study areas, with some farther locations recording higher signal strength compared to closer locations to the transmitter contrary to theoretical expectation. The overall results show that elevation above ground level is a key factor to be considered for UHF transmission and reception (location of transmitters, transmitting antenna's height, directivity and gain. Others are, transmitter output power, receiving antenna's height and gain) in the study areas.

The content presented in this article provides an insight into the current topology maintenance techniques in general and algorithms in particular. It makes the fine line between topology control, topology construction and topology maintenance all the more prominent. Additionally, it tries to find out how the meaning of topology control has evolved over a period of time since the inception of Wireless Sensor Networks (WSN). An attempt has been made to standardize the definition of topology control and topology maintenance. 

Hyperthermia is a thermal therapy for cancer treatment in which body temperature is exposed to elevated temperature of 40-42oC. Microwave ablation has a potential to be sensitive to changes in the dielectric tissue parameters which results in damaging abnormal tissues. In order to produce heat in the focused area microwave signals are adjusted in time, frequency and strength. The commonly used frequencies in microwave imaging systems are 415MHZ and 2.45GHZ which are transmitted from the antennas enclosing the relevant body part. This paper presents a highly efficient E-Shape micro strip patch microwave antenna operated at 2.45 GHz which can be used in various applicators for hyperthermia treatment system. The simulation is done on IE3D simulator. The results are compared at two feeding points 1 and 2 for the frequency 2.45GHZ. It gives return loss of -19.3dB, bandwidth of 6.2dB and the antenna efficiency of 92% for feeding point 1 which proves to be highly effective in communication.

This paper is concentrated on comparison of rectangular patch antenna with different ground plane dimensions i.e. short edge, double ground, triple ground in terms of Bandwidth, Gain, Directivity, VSWR, Reflection coefficient and efficiency performance. The finite ground plane gives rise to diffraction of radiation from the edges of ground plane resulting in modifying of radiation conductance, radiation pattern, and resonant frequency. The substrate used is Flame Retardant-4epoxy having dielectric constant of 4.4 and dielectric tangent loss of 0.02. The patch antenna is provided by inset feed line. The design was optimized to obtain the most suitable configuration in terms of desired values of reflection coefficient, bandwidth and Voltage Standing Wave Ratio (VSWR) for antenna with and without modifying on ground plane. These antennas are suitable for WLAN Applications. In this observation, the paper calls for an attention that, the cachet is an amelioration of the 2.4 GHz Industrial, Scientific and Medical (ISM) Band patch antenna is simulated and analysed using HFSS 13.0 and fabricated by photo lithography. The proposed antenna is tested using VNA E5071C.As a result it can be also observed in being when the size of ground plane is increased, the ripples in the main pattern diminishes. 

It has been well established that the lifetime of a Wireless Sensor Network (WSN) depends on the energy of the sensor nodes which is limited by the battery capacity of the nodes. This challenge has led to research efforts towards developing a more efficient energy based routing algorithms and architectures. One of such popular algorithm is the Low-Energy Adaptive Clustering Hierarchy (LEACH). The LEACH approach adopts randomized rotation of local base stations (or cluster-heads (CH)) to evenly distribute energy load amongst the sensors in the network. A variant of LEACH known as Vice-LEACH (V-LEACH) introduces the concept of a vice-CH that takes over the role of the main CH in the event of CH death. Random selection of cluster- head node in both LEACH and V-LEACH ignore node's residual energy and the optimal number and distribution of cluster head is not ensured in all rounds. This work presents an enhanced cluster-based routing algorithm which took into consideration the residual energy of nodes in the network while maintaining the optimal number of CHs throughout the network lifetime. A sensor network was developed on OPNET Modeler software tool and simulation tests were performed to evaluate the performance of the enhanced routing algorithm on the network. Simulation results showed that this enhanced routing algorithm distributed network energy consumption across the network nodes hence significantly improving the lifetime of the sensor network. 

In the past decade, Wireless sensor networks (WSNs) have attracted very much attention from the research and industrial community. Various WSN based projects produced fruitful and interesting results. In various applications, the location information of node is vital for the service. The reason is that users usually need to know what happens, but also where the concerned events happen. For example, in battlefield surveillance, the knowledge of where the enemy comes from can be much more important than only knowing the appearance of the enemy, it is much important that sensors reports the information along with their location. Localization is one of the primary and widely useful middle-ware services in sensor networks, mostly allows every node to obtain its location information. The localization schemes can be categorized on the basis of various parameters like availability of GPS, presence of anchors, range measurements, model of computation etc. On the basis of computation model, the localization approaches can be categorized into: centralized and distributed localization techniques. Due to certain advantages, distributed localization is flattering as an active stem in sensor localization. In this paper, we have been reported a detailed analysis on distributed localization techniques and outline the merits and limitations of distributed localization schemes in WSNs. Finally, we conclude the paper with some open issues. 

Orthogonal Frequency Division Multiplexing (OFDM) signaling has been widely used for high data rate transmission applications due to its high spectral efficiency and robustness to the frequency selective fading channels. One of the major drawbacks of the analog OFDM system is frequency shifting in every sub-carrier. That's why bit error rate increased in analog OFDM system. In this research, we want to solve the problem of the analog OFDM system by using IFFT circuit instead of the local oscillator. The IFFT circuit takes an input as frequency domain and provides output as a time domain signal for 4-QAM modulation. Basically IFFT circuit acts as a local oscillator in the analog OFDM system. The IFFT circuit only executes operation on a discrete frequency domain signal which is converted into a time domain signal by its. So no frequency shifting occurs in every sub-carrier in the digital OFDM system. As a result BER also decrease in digital OFDM system over the analog OFDM system.