No abstract

The quality of medical image is crucial due to the sensitivity of medical diagnoses. Nowadays medical images are commonly shared between various entities across the medical sector to improve the quality of diagnoses. Thus, watermarking process is usually applied on these images to embed patient’s private information. One of the key challenges is preserving image quality, keeping it clean of distortions after the watermarking process, and sustaining robustness. In this work, a hybrid Discrete Cosine Transform (DCT) and Singular value decomposition (SVD) based image watermarking scheme with chaotic encryption is proposed. The obtained results have demonstrated that the proposed scheme is secure and robust compared to the present schemes. In particular, the results show decent robustness and excellent imperceptibility of watermarked host medical images. Moreover, Peak signal to noise ratio (PSNR), and Normalized Correlation (NC) are used to evaluate the performance of the scheme. The scheme has shown a minimum PSNR of 59 dB and an NC value of 1 with no attacks applied, and not less than 0.5 with the presence of various attacks.

In this paper, a new antenna system for rapidly emerging multifunction devices is presented. The proposed antenna system consists of four antenna components each one operating at different frequency bands separately. The designed antennas are isolated and integrated on a single substrate. The first antenna is designed to operate at 1920–2170 MHz covering the UMTS band, whereas the second antenna is proposed for the lower band 5G systems and WiMAX operating within the frequency range of 3.4–4.2 GHz. Furthermore, another antenna is designed to cover the higher band 5G system and the IEEE 820.11a WLAN within the frequency range of 5.1–5.85 GHz. Finally, a 28 GHz bowtie-based MIMO antenna array is designed and simulated for the mmWave future 5G mobile networks. The proposed antennas were designed and simulated by using CST microwave studio. The results showed that all of the proposed antennas exhibited excellent reflection characteristics below −20 dB at the resonant frequency and achieved high radiation efficiency reached 99% in some cases with a peak gain ranging between 4–6 dBi. The proposed antenna system helps smartphones to perform multitasks and achieve a better-quality operation especially with the enormous growth of IoT techniques.

This paper presents a low-cost, compact, beam-steering phased array antenna (PAA) system based on a novel approach to integrating low-cost, high-performance phased shifters with their controlling boards within an antenna structure. Consequently, the system has been reduced to one structure for the antenna array and integrated phase shifters, rather than the sophisticated PAA with two separate boards which are connected by RF coaxial cables. The system has been achieved by the following stages; Firstly, the steering vector weights matrix was calculated by MATLAB. Then, four elements of uniform linear Microstrip patch antenna array with their feeding network power divider were designed and simulated in the CST simulation program. As a result, a practical model has been implemented. The designed RF-PCB for the 4-bit phase shifters MAPS_010143 were integrated within the antenna panel. The system works at a resonance frequency of (2.4 GHz), with (±45°) steering capability. The results are presented for the three models. The practical results match the simulation results very closely, fence proving the accuracy of the model and demonstrating a highly effective design.

This paper presents the design and investigation of array antennas formed of two narrow rectangular slots. Two approaches for feeding the two slots by microstrip lines are investigated as well as the influence of changing the distance between the slots on the radiation pattern. The two slots are etched on one side of the substrate, while the feed network is placed on the other side. Two designs, depending on the feeding approach, are presented. In the first design, a simple T-shaped divider is used to feed the two slots, while the second design is based on a single microstrip line which feeds the two slots in series. Two antennas are for the first design, each with dimensions of 57.83 × 41.3 mm 2 , while those of the second design have dimensions of 83.45 × 36.9 mm 2. The four proposed designs have been simulated and optimized using Computer Simulation Technology (CST-MWS) simulation program. Prototypes were fabricated and tested to verify the designs. The four antennas achieved −10 dB impedance bandwidths between 8.6% and 9.4%, while the gain values were between 4.7 dB and 5.7 dB. The comparisons between the fabricated and simulated antennas considered the reflection coefficient and radiation pattern showing good agreement.