No Arabic abstract
Ultra-wideband is increasingly advancing as a high data rate wireless technology after the Federal Communication Commission announced the bandwidth of 7.5 GHz (from 3.1 GHz to 10.6 GHz) for ultra-wideband applications. Furthermore, designing a UWB antenna faces more difficulties than designing a narrow band antenna. A suitable UWB antenna should be able to work over the Federal Communication Commission of ultra-wide bandwidth allocation. Furthermore, good radiation properties across the entire frequency spectrum are needed. This paper outlines an optimization of fractal square microstrip patch antenna with the partial ground using a genetic algorithm at 3.5 GHz and 6 GHz. The optimized antenna design shows improved results compared to the non-optimized design. This design is optimized using a genetic algorithm and simulated using CST simulation software. The size of the optimized design is reduced by cutting the edges and the center of the patch. The optimized results reported, and concentrated on the rerun loss, VSWR and gain. The results indicate a significant enhancement as is illustrated in Table II. Thus, the optimized design is suitable for S-band and C-band applications.
Microstrip patch antennas (MPAs) are rapidly gaining more attention due to the proliferation of communication devices and systems with frequencies becoming more suitable for the size and performance of this type of antenna. Due to recent advancements in semiconductor technology, high dielectric constant materials are used to achieve additional size reduction which has made MPAs very useful and popular in the design of mobile devices and wireless systems. However, MPAs suffer from problems associated with narrow bandwidth and low gain. Techniques employed for improving the performance of MPA hinge on tweaking features such as the patch size, substrate height, ground plane size and feeding method. In view of this, this research designs and analyzes the performance of an X-band MPA for wireless systems using CST Microwave Studio. Including the ground plane, the proposed design has a low profile structure of 17 mm x 17 mm x 1.6 mm which is suitable for wireless systems. The proposed design also resonates at a frequency of 10 GHz with an omnidirectional radiation pattern exhibiting a gain of 7.2 dBi. Return Loss, VSWR, Gain and Radiation Pattern are the performance indicators employed in this research. The proposed MPA design demonstrates marked performance improvement when benchmarked with a similar MPA designed for 5G applications.
In this paper, a single layer Coplanar Waveguide-fed microstrip patch antenna array is presented for biomedical applications. The proposed antenna array is realized on a transparent and flexible Polyethylene Terephthalate substrate, has 1x4 radiating elements and measures only 280 x 192 mm2. The antenna array resonates at 2.68 GHz and has a peak-simulated gain of 10 dBi. A prototype is also fabricated, and the conductive patterns are drawn using cost-efficient adhesive copper foils instead of conventional copper or silver nanoparticle ink. The corresponding measured results agree well with the simulated results. The proposed low profile and cost-efficient transmit antenna array has the potential for wearable born-worn applications, including wireless powering of implantable medical devices.
We employ an evolutionary algorithm to automatically optimize different stages of a cold atom experiment without human intervention. This approach closes the loop between computer based experimental control systems and automatic real time analysis and can be applied to a wide range of experimental situations. The genetic algorithm quickly and reliably converges to the most performing parameter set independent of the starting population. Especially in many-dimensional or connected parameter spaces the automatic optimization outperforms a manual search.
In this paper, the real-time deployment of unmanned aerial vehicles (UAVs) as flying base stations (BSs) for optimizing the throughput of mobile users is investigated for UAV networks. This problem is formulated as a time-varying mixed-integer non-convex programming (MINP) problem, which is challenging to find an optimal solution in a short time with conventional optimization techniques. Hence, we propose an actor-critic-based (AC-based) deep reinforcement learning (DRL) method to find near-optimal UAV positions at every moment. In the proposed method, the process searching for the solution iteratively at a particular moment is modeled as a Markov decision process (MDP). To handle infinite state and action spaces and improve the robustness of the decision process, two powerful neural networks (NNs) are configured to evaluate the UAV position adjustments and make decisions, respectively. Compared with the heuristic algorithm, sequential least-squares programming and fixed UAVs methods, simulation results have shown that the proposed method outperforms these three benchmarks in terms of the throughput at every moment in UAV networks.
A novel and compact dual band planar antenna for 2.4/5.2/5.8-GHz wireless local area network(WLAN) applications is proposed and studied in this paper. The antenna comprises of a T-shaped and a F-shaped element to generate two resonant modes for dual band operation. The two elements can independently control the operating frequencies of the two excited resonant modes. The T-element which is fed directly by a 50 $Omega$ microstrip line generates a frequency band at around 5.2 GHz and the antenna parameters can be adjusted to generate a frequency band at 5.8 GHz as well, thus covering the two higher bands of WLAN systems individually. By couple-feeding the F-element through the T-element, a frequency band can be generated at 2.4 GHz to cover the lower band of WLAN system. Hence, the two elements together are very compact with a total area of only 11$times$6.5 mm$^{2}$. A thorough parametric study of key dimensions in the design has been performed and the results obtained have been used to present a generalized design approach. Plots of the return loss and radiation pattern have been given and discussed in detail to show that the design is a very promising candidate for WLAN applications.