A novel compact fractal UWB antenna with triple reconfigurable notch reject bands applications

A compact, circular UWB fractal antenna with triple reconfigurable notch rejection bands is proposed. It rejects the crowded frequency bands WiMAX, WLAN and X band interferences produced in UWB communication systems. The proposed fractal structure consists of a basic circular patch with circular fractal iterations. By employing this new structure of fractals, the overall size of antenna is reduced 53% to 21 × 25 mm, in comparison with traditional circular monopole antenna. The implemented antenna operates at 3.1–10 GHz. Re-configurability is realized by designing slots and split ring resonators in desired frequencies with the attached PIN diodes. WLAN band rejection was realized by creating a pair of optimized L-shaped slots in the ground plane. By etching a split ring resonator and a U-shaped slot, X and WiMAX bands were also rejected. Furthermore, by attaching diodes to aforementioned slots and designating the diodes on/off, different bands can be included or rejected. In time domain, the antenna properties are evaluated by a figure of merit called fidelity factor. Finally, the antenna properties are measured in anechoic chamber and the results agrees with simulation findings

Emergency Water Information Network (EWIN)

Flooding is a global problem and as a representative example, Mexico is currently struggling to manage flood situations which are increasing in regularity and severity. Many developing countries have substandard flood monitoring infrastructure. However, in common with the UK, they have state-of-the-art cellular mobile phone systems. In this research, expertise in water engineering and radio communications from the UK and Mexico have been combined to design a cost effective flood forecasting system based on hydrology sensing and mobile networks. Recent events such as hurricane Patricia in Mexico (October 2015) has emphasised the need for systems that can predict the dynamic behaviour of large-scale water flows. Currently, management of flood situations in many developing countries is carried out through prediction of water behaviour (Hydro Meteorological Warning System). This system is based on estimates of rainfall, runoff and water levels. In Mexico two central registers and rain measuring stations are used to gather data. The data collected is compared with pre-established risk thresholds which determine whether a warning should be issued. In general, the rainy season in Mexico occurs during the summer and fall, starting in May and ending in October. Along the main waterways, the change in state is dynamic between dry and rainy both in terms of the water volume in the channels and the vegetation on the banks. Vegetation in Mexico is normally sparse but grows quickly and in abundance during the rainy season. During flood events, new rivers form along river beds that are normally empty. These conditions are typical of flooding in many countries. In order to develop a real time flood forecasting system, several areas of research need to be investigated. These include: data sensing at the appropriate location and time, wireless transmission of flood data, sensor data fusion, model generation and prediction at the remote weather station. This multidisciplinary research project is addressing each of these areas by employing UK expertise in Water Engineering and Radio Communications to complement the research base in Mexico

Channel models for underwater acoustic communications

The successful transmission of high-speed digital data through any medium requires a knowledge of the degradations and distortions introduced into the received signal by the medium itself. This knowledge can then be used to design suitable detection schemes, usually based around adaptive equations, to take account of the distortion when detecting data from the received signal. In the case of an underwater communication channel, these degradations are mainly caused by multipath propagation of the transmitted signal energy, which for the realistic cases of turbulent sea conditions, non-homogeneous media and acoustic scattering will be time-varying in nature. It follows that the received signal can suffer severe and rapid amplitude fluctuations (fades) across the bandwidth of the signal. [Continues.

RFID light weight server-less search protocol based on NLFSRs

© 2016 IEEE.Spectacular expansion of RFID systems and applications by several industries such as business, electronics, health, marketing, transportation, etc. has made RFID ever more popular. Within this context, the industry search for lower tag weight and low cost system together with solemn security to satisfy the consumer. Tag search is among the most requested protocols in such systems. Being light weight is regarded as another important specification for the said protocols, so that they can be utilized in low expense tags. In this paper, a server-less search protocol is proposed in low expense tags with the aid of NLFSRs and simple logical operations to conflict with security attacks. This protocol requires only a two steps information exchanges between tag and reader, and although it has simple structure, but is completely safe against most of the known security attacks. In comparison with other protocols, this protocol also requires a small number of gates for implementations. There are no need to exclude the collisions in tags as its other privileges

Application of fractal binary tree slot to design and construct a dual band-notch CPW-ground-fed ultra-wide band antenna

A compact dual band-notch ultra-wide band (UWB) antenna with a co-planar waveguide (CPW)-ground-feed is presented. A desired band-notch antenna is achieved by etching a narrowband dual resonance fractal binary tree into the radiating element of an existing UWB antenna. The new antenna reduces interference from UWB in the wireless local area network (WLAN) bands by attenuation of the measured return. The built prototypes have a compact size of 16×22 mm2 including the ground plane. This miniature size also delivers advantageous radiation patterns with good mono-polar characteristics across the UWB band. For this design the gain is attenuated within the desired WLAN bands. The maximum suppression obtained for the stops at 5.65 and 9.9 GHz are -13.1 and 7.2 dB, respectively

Wideband fan-beam low-sidelobe array antenna using grounded reflector for DECT, 3G, and ultra-wideband wireless applications

low-sidelobe fan-beam wideband linear array antenna employing a nonparasitic grounded reflector is presented. This fan-beam antenna is achieved using a six-element conventional planar monopole array antenna and feed network, which together produce sidelobes at 26 dB. Dolph–Tschebyscheff distribution is employed, and a broadband array feed network is designed to satisfy beneficial input impedance bandwidth requirements in the frequency range 1.7–2.2 GHz. Therefore, this array covers applications of GSM-DCS2, DECT, and 3G. Combining planar monopole antenna as an array with nonparasitic grounded reflector allows an advantageous fan beam pattern to be generated. H-plane 3-dB beamwidths are controllable using grounded reflector height. In addition, the results are compared with and without reflector array antenna