This paper focuses on radiofrequency (RF) coils that can produce a high electromagnetic field homogeneity to be used for magnetic resonance imaging (MRI) applications. The proposed structure is composed of four wire loops symmetrically located on an ellipsoidal surface. The main objective of this work is to improve field homogeneity compared to a standard Helmholtz coil. Numerical simulation was carried out to assess the RF electromagnetic field behavior of the proposed coil. Different electrical modeling and simulations were investigated, particularly the study of the whole modeling of the proposed structure taking into account all the couplings between the loops. The proposed coil was evaluated and compared with the standard Helmholtz coil. Simulation and experimental results confirmed the good performance of the developed coil in terms of electromagnetic field homogeneity, efficiency, sensitivity, and quality factor.

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A dust storm is the main attenuation factor that can disturb receiving radio signals in arid climate condition as in Saudi Arabia. This paper presents a study on the effect of dust storms on the received radio frequency power in a homogenous environment in the city of Riyadh. A number of micrometer and millimeter wave links have been considered along with several measured dust storm data to investigate the dust storm effects. The results showed that dust storm can critically influence the communication link and this effect grows up as the physical distance between the transmitter and the receiver increases. The negative effect of the dust storm apparently appears at high-frequency bands allocated for the next communication generation (5G) which imposes finding solutions to mitigate the effects of this phenomenon.

A conventional temperature sensing system employs a single transducer to convert temperature into an electrical signal. Such a system suffers from the limitation of the sensing range of the sensing device thereby affecting its accuracy and its capability. Therefore to make an accurate measurement in a typically abrupt temperature varying environment, a broad range high precision sensor is required. In this paper, an attempt is made to implement a wide spectrum temperature measurement system using auto-selected multi-sensor core in LabVIEW. This multi-sensor core can be composed of a set of different sensors having different capabilities to measure different temperatures ranges. These sensors are auto-selected by the program depending on the environment. This concept may be useful for space applications or it can also be useful for the monitoring of temperature and pressure in an oil/gas transportation or supply by means of underground/sea pipeline system or in a refinery plant. Further, this may also be applied for high precision temperature sensing in magnetic resonance imaging system applications.

In this paper, we present the design and testing of a radiofrequency prototype coil with good performances in terms of B 1 magnetic field homogeneity and can be utilized for Magnetic Resonance Imaging. It is constituted of four coaxial separately tuned rings of wire and symmetrically located on a spherical surface. Compared to standard Helmholtz pair, which has 2nd-order magnetic field homogeneity, it yields to improvement in field homogeneity, while preserving the simplicity of design. The four coils of proposed structure are tuned to the same frequency. The proposed structure gets at 4th-order magnetic field homogeneity by optimizing the distance between rings and the diameters of outer loops. An electrical modeling of the four-coil system taking into account the coupling effects between all rings permits to determine the resonance frequency in the homogenous mode. Measurements of B1 field homogeneity were introduced in free space. Compared to the Helmholtz coil, the proposed structure presents good performances in terms of B1 homogeneity, quality factor and sensitivity. The design of proposed coil has been optimized for best SNR performances. Globally, this work claims to be a contribution to the study of the four-coil RF systems derived from the Helmholtz pairs.