New proposed spherical slotted antenna covered by the layers of dielectric material and plasma

The operation of the new proposed spherical slotted antenna covered by layers of dielectric material and plasma was analyzed numerically in this paper. By utilizing the Integra-functional equations method, the optimum thickness of dielectric material layer and suitable conditions which improve the operation of this antenna are analyzed here by MATHCAD. The thickness of dielectric layer must not be less or more than λ/6. Furthermore, the authors propose manipulating the operation frequency to enable such antenna to work in most circumstances

Cooperative Reception of Multiple Satellite Downlinks

Popular small satellites host individual sensors or sensor networks in space but require ground stations with directional antennas on rotators to download sensors’ data. Such ground stations can establish a single downlink communication with only one satellite at a time with high vulnerability to system outages when experiencing severe channel impairments or steering engine failures. To contribute to the area of improving the reception quality of small satellites signals, this paper presents a simple receive diversity scheme with proposed processing algorithms to virtually combine satellite downlink streams collected from multiple omnidirectional receivers. These algorithms process multiple received versions of the same signal from multiple geographically separated receiving sites to be combined in one virtual ground station. This virtual ground station helps detect the intended signal more reliably based only on a network of simple and cooperating software-defined radio receivers with omnidirectional antennas. The suggested receive diversity combining techniques can provide significant system performance improvement if compared to the performance of each individual receiving site. In addition, the probability of system outages is decreased even if one or more sites experience severe impairment consequences. Simulation results showed that the bit error rate (BER) of the combined stream is lower than the BER of the best quality receiving site if considered alone. Moreover, virtual ground stations with cooperative omnidirectional reception at geographically separated receivers also allow data to be received from multiple satellites in the same frequency band simultaneously, as software-defined receivers can digitize a wider portion of the frequency band. This can be a significant conceptual advantage as the number of small satellites transmitting data grows, and it is reasonable to avoid the corresponding necessary increase in the number of fully equipped ground stations with rotators

Collaborative Network of Ground Stations with a Virtual Platform to Perform Diversity Combining

SGS-2021-005A conventional ground station can establish a single downlink with only one satellite at a time through steerable high-gain antenna. In addition to the lack of tracking more than one satellite at once, such single radio communication is highly vulnerable to outages when experiencing severe degrading circumstances or even with steering engine failures. Accordingly, such problematic single radio link would leave the operator with no alternative options to overcome the consequences. This work exhibits a solution to the ground station through networking. Multiple ground stations, with omnidirectional antennas instead of the steerable directive ones, can be engaged in a collaborative network to receive multiple versions of the same transmitted data for processing and combining. The suggested receive diversity combining is performed at a virtual ground station which utilizes a combining algorithm to help detect the original data from the received versions with less errors and hence reflecting more efficient and reliable services. To exploit this aimed diversity gain, a simple combining algorithm is also developed in this article. The simulation results from the proposed scheme have indicated significant performance enhancement over the single site ground station. This cooperative scheme will not only improve the system performance but also offer to track more than one satellite at a time

A numerical analysis of a HYBRID PV+WT power system

The increase in global energy consumption and the expected exhaustion of traditional energy sources, especially in the last century, led to an increased search for alternative sources of energy.The use of renewable energy sources has become extremely important to reduce dependence on fossil fuels. Due to the stochastic nature of the renewable energy sources such as the wind speed fluctuation and the intensity of solar radiation the stable operation of the systems base single renewable source can be problematic. But the using two or more of these sources results in higher stability than relying on a single source. For this reason, hybrid renewable energy systems have become an attractive solution in thefield of renewable energy. A hybrid energy system is a combination of two or more renewable energy sources that can enhance each another to increase the reliability of the supplied energy. The objective of this paper is investigation about the energy supplying improvement and the energy efficiency utilisation by hybridisation using two renewable energy resources: wind energy and solar energy with respect two different optimisation objectives: economical to reduce the net present cost and ecological to reduce CO2 emissions. Presented system has been implemented to supply a single household with an electric load