Specific attenuation and depolarisation in rain from 2-dimensional video disdrometer data

Data from 2-dimensional video disdrometers (2DVD) taken in different locations are used to derive the specific attenuation for horizontal and vertical polarisations at 20 GHz. The data include both drop-size distribution and their axis ratio distributions. T-matrix calculations using data over 1 min integration time show a power-law dependence on rain rate. The best-fit coefficients are compared with those given in the ITU-R Recommendation P. 838, both versions 2 and 3. Closest agreement is seen for vertical polarisation for version 2 and the largest discrepancies are seen for horizontal polarisation for version 3. The discrepancies are attributed to the different assumptions in the drop-size distributions, as well as the upper limit of integration for deriving the specific attenuation. The variation of the crosspolar discrimination (XPD) against copolar attenuation (CPA) is also examined. The 2DVD data are used to simulate a beacon experimental scenario at 20 GHz, the actual locations of the two instruments being different but climatically similar. Good agreement is seen with one year of beacon measurements, but the latter shows more spread in the variation, partly attributed to drop oscillations. Calculations also show that XPD-CPA variation is sensitive to the assumed drop shapes     

Performance Enhancement with Improved Security an Approach for Formulating RFID as an Itinerary in Promulgating Succour for Object Detection

Wireless Personal Communications - In real time process, tracking of objects allows an agency to record, track, and examine an object and these features enhance the public service through better...     

Correction to: A Detailed Evolutionary Scrutiny of PEIS with GPS Fleet Tracker and AOMDV-SAPTV Based on Throughput,Delay, Accuracy,Error Rate,and Success Rate

Wireless Personal Communications - Radio frequency identification (RFID) is a promising and widespread wireless communication technology for entity identification or authentication. By the emerging...     

A vertically-pointing Doppler radar to measure precipitationcharacteristics in the tropics

Describes the design and preliminary results from a vertically-pointing pulsed S-band Doppler radar, capable of measuring reflectivity (dBZ), linear depolarization ratio (LDR), and the Doppler spectrum. The data reported were acquired during a short experimental campaign while the radar was sited in Southern UK. The system has now been sent to Papua New Guinea for a 12 month programme of statistical measurements on the nature of tropical rainfall. The results from this study will be applicable to communications system engineering in the tropics, and in providing ground truth for satellite-based rainfall measurements for global climatic modeling     

Design,analysis and characterization of four port multiple-input-multiple-output UWB-X band antenna with band rejection ability for wireless network applications

Wireless Networks - In this proposed research article, four-port dual notched bands multiple-input-multiple-output (MIMO) antenna configuration is proposed and is experimentally investigated by...     

A Detailed Evolutionary Scrutiny of PEIS with GPS Fleet Tracker and AOMDV-SAPTV Based on Throughput,Delay, Accuracy,Error Rate,and Success Rate

Wireless Personal Communications - Radio Frequency Identification (RFID) technology is projected to address the issue of handling the bulk of nodes for consequently recognized and tracking tags...     

Radiowave propagation research in the tropics using a transportablemultiparameter radar system

Although accurate models for Earth-space microwave propagation, based on extensive measured data, exist for temperate regions of the world, this is not the case for the tropics. With the proliferation of satellite communications in these areas, it has become important to test the validity of currently recommended techniques for calculating circuit availability and co-channel interference levels due to attenuation by precipitation and scattering from precipitation, respectively. Multiparameter radar measurements, employing both polarimetric and Doppler techniques and made over a significant period of time on a statistically-valid basis, provide an ideal tool for these investigations. The paper describes the design considerations for, and construction of such a radar. A selection of its data products are presented, illustrating its potential for radio propagation and meteorological research     

Freezing height distribution in the tropics

The calculation of fade margins required to meet the user‐specified availability criteria needs to take into consideration a number of meteorological factors specific to the earth‐station location. One such factor is the annual average of the freezing level height. Information on this height is available in ITU‐R Recommendation P. 839‐3, which provides contours that are generated on a 1.5° by 1.5° latitude by longitude resolution grid. This paper compares these heights with the bright‐band heights (BBH) obtained from the precipitation radar on‐board the TRMM (Tropical Rainfall Measuring Mission) satellite. Four years of TRMM radar data have been analysed, and their averages are compared within the latitude range covered by the satellite orbit (35°N to 35°S). Comparisons show that the radar bright‐band heights typically occur 300 m below the 0°C isotherm heights. However, results also indicate that this difference may be latitude dependent. Also examined are the year‐to‐year variability and the seasonal variation. In the former case, only 1998 showed BBH values which are somewhat higher in tropical regions, this year having had one of the strongest El Niño events recorded. In the latter case, results show significant seasonal variation, becoming more pronounced at higher latitudes. Copyright © 2003 John Wiley & Sons, Ltd.     

The Chilbolton advanced meteorological radar: a tool formultidisciplinary atmospheric research

An ex-air-surveillance S-band radar was installed on the 25 m antenna at Chilbolton, near Winchester, over 20 years ago for studies of the effects of rain on communications systems. Since that time the functionality of the radar has been steadily developed to keep it at the forefront of meteorological research radars throughout the world. Recent developments have added phase and Doppler capabilities to the radar. The paper briefly discusses the use of differential reflectivity measurements in determining rainfall rates, microwave attenuation and the phase of hydrometeors. The new hardware and signal processing are described and examples of radar scans and applications of the radar are presented