Network coordinates (NC) system is an efficient mechanism for Internet distance prediction with scalable measurements. The intrinsical cause for the unsatisfactory accuracy of the simulation-based NC algorithms has been identified. Then Pharos, a fully decentralised and hierarchical scheme, is proposed to solve this problem. Pharos leverages multiple coordinate sets at different distance scales...

An ultra-wide-band (UWB), stripline-fed Vivaldi antenna is characterized both numerically and experimentally. Three-dimensional far-field measurements are conducted and accurate antenna gain and efficiency as well as gain variation versus frequency in the boresight direction are measured. Using two Vivaldi antennas, a free-space communication link is set up. The impulse response of the cascaded...

Singleand dual-polarized arrays of Vivaldi notch elements have been extensively analyzed by using efficient numerical analyses. From these analyses and from experimental studies, element designs and array configurations have been determined to provide more than two octaves of bandwidth while scanning to 45° from broadside in all directions. Parameter studies illustrating the effects of some key...

A frequency agile Vivaldi antenna whose operating frequency band can be switched between two selected bands is proposed in this paper for spectrum monitoring and cognitive radio applications. A RF switch is introduced into the back-slot of a Vivaldi antenna to allow switching of the operational band. The realised gains of the antenna are 10.5 dBi in the low band around 3.1 GHz, and 12 dBi in hi...

A novel idea of conformal corrugated edges (CCE) is put forward in this paper for tapered slot antennas to obtain improved low-frequency characteristics. The CCE is realized using conformal slots whose two longitudinal boundary lines are modelled using curvilinear function of the curves that form the tapered slots. So the conformal slots can sufficiently corrugate edges of the tapered slot ante...

ne lesson offered by historical studies of musical styles is that the greatest composers almost never abandon their musical heritage entirely even in their most progressive compositions. They tend to build their works upon existing styles and genres, and then transform them into new styles in ways unprecedented in their times. Josquin des Prez, the “Beethoven of the Renaissance,” has been regar...

In this research work, a multibeam antenna which is a combination of a beamformer network (BFN) and a linear array antenna, has been designed. A Rotman lens has been chosen as beamformer network and Vivaldi antennas have been selected for constructing array antenna. The Substrate Integrated Waveguide (SIW) was used for implementing Rotman lens. After explanation the structure of Substrate integ...