One of the major challenges in the design of SKAI is the required ultra-wide frequency bandwidth. The decade of bandwidth could be split up into several frequency regions. For each region a separate radiator could be used with an element distance smaller than λ/2 in order to avoid grating lobes. The main disadvantages of this concept are the complexity (costs) and mutual coupling between the va...

In this paper, a hybrid dual-band cylindrical dielectric resonator antenna with parasitic slot fed by a microstrip line that is suitable for wireless body area network is proposed. In this configuration, the dielectric resonator performs the functions of an effective radiator along with the feeding structure and the slot in the ground plane. By optimizing the structural parameters, the antenna ...

The change from steerable motor to rotary steerable system has been both technically and commercially successful in Lybia. Through these case histories the paper will demonstrate benefits resulting from the use of rotary steerable systems that have led to a step change in overall drilling performance in the Middle East. This paper describes the successful introduction and application of a rotar...

An analysis is accomplished of the input power requirement of High-Frequency Gravitational Wave (HFGW) generators. Several techniques are explored using both off-the-shelf and advancednanotechnology generator elements. It is concluded that proof-of-concept test, involving N off-the-shelf array elements could be of meter to kilometer length and require 25 MW or less power if array elements are i...

[1] ELF/VLF radio waves (300 Hz–30 kHz) are difficult to generate with practical antennae, because of their extraordinarily long (10–1000 km) wavelengths, and the lossy nature of the Earth’s surface at these frequencies. ELF/VLF waves have been successfully generated via amplitude modulated (AM) HF (2–10 MHz) heating of the lower ionosphere. Through the temperature-dependent conductivity of the...

We present a means of containing Wi-Fi coverage to physical boundaries that are meaningful to users. We call it geo-fencing. Our approach is based on directional antennas, and our motivation is to provide wireless access and privacy models that are a natural fit with user expectations. To evaluate geo-fencing, we use measurements from an indoor testbed of Wi-Fi nodes and APs with electronically...

The emerging applications of the parametric loudspeaker, such as 3D audio playback systems, require both controllable directivity and high fidelity at the audible frequency (a.k.a. the difference frequency). Although phased array techniques have been applied and proven adequate to steer the mainlobe of a parametric loudspeaker, and preprocessing methods have been studied to reduce the harmonic ...

The paper studies the effect of clay soil blocking the heat transfer area of the radiator on the engine coolant temperature by developing a mathematical model. The results of the study indicated that the percentage area covered resulted in a proportional increase of the inlet and outlet temperatures of the coolant in the radiator. The mathematically model developed also predicted the experiment...