Demyana Adel Saleeb

Human footsteps are a sustainable energy source that is derived from kinetic energy. As a result, in this study, piezoelectric sensors placed beneath floor tiles were excited by human footsteps to provide practical electrical energy. A simple rectifying circuit with a filter was used to capture electrical power. The floor tile is 455 mm in length and 405 mm in width. Two light-emitted diodes were lit up as the actual load by utilising electrical energy obtained from the kinetic energy generated by human footsteps. The greatest attainable power that could be extracted from the suggested floor tile was 249.6 milliwatts, with an approximate cost of $10.2.

Purpose: One of the sustainable energy sources derived from kinetic energy is human footsteps. This research sought to find a substitute for conventional power sources to lessen dependence on them. As a result, a floor tile excited by human footsteps was demonstrated and presented to generate usable electrical power. Methods: Piezoelectric patches, hot melt glue sticks, wood plates, and foam plates are just a few of the commercially available materials used in the suggested technique, making it suitable and practical. In addition to the components, uncomplicated circuits like a voltage multiplier and rectifier with a capacitance filter were employed for the electrical power capture. The proposed prototype has a length of 455 mm and a width of 405 mm. Results: Two LEDs were effectively illuminated as an actual load using electrical energy collected from human footsteps. The maximum useful power that could be harvested successfully via the proposed floor tile (one tile) was 246 mW, with an approximate cost of $10.2. Conclusions: Designing an array of footsteps-based energy harvesting tiles covering broad areas to maximize the harvested power could be considered as a future work. Moreover, the number of pedestrians variable can be also studied for the proposed design of this study in a real excitation environment such as a railway station, subway station, street, discotheque, and wedding festival hall.

Graphene is being used as a patch as it possesses a number of desirable electromagnetic and mechanical properties that assist in providing flexible and reconfigurable antenna structure. A graphene reflective unit cell is examined to demonstrate that the reflection coefficient can be controlled by changing the chemical potential and size of the graphene patch. The phase compensation of the reflected waves is achieved by patches with different sizes. Reflection coefficient phase variations for 0°–525° with a variable slope are obtained for different graphene conductivities. A graphene-based reflectarray antenna is proposed. A reflect array with dimensions of that operates at 1.6 THz is analyzed. The reflectarray is composed of 40x40 unit cells with for each unit cell size. They are placed upon silicon dioxide substrate. A horn antenna is used as a feed. The focal-length-to-diameter (F/D) ratio is equal to one. A maximum gain of 20.7, 13.6, and 21.4 dBi are obtained at 1.4, 1.8, and 1.6 THz respectively.

The use of a circularly polarized patch antenna array to detect kidney cancer by microwave techniques is proposed in this paper. A four-element linear antenna array is designed and fabricated at the ISM frequency of 2.4 GHz. The dimensions of the antenna array are 200 mm $\times78$ mm. The single element is a square patch with side length of 30 mm. The distance between patches is chosen to be 20 mm which ensures that mutual coupling between any two adjacent patches is less than 20 dBs. The substrate is a FR-4 material of relative permittivity 4.3 and thickness 1.6 mm. The circular polarization has an axial ratio of 0.8 dB at 2.4 GHz. The bandwidth at S ₁₁ = −10 dB is 7.23 %. Renal system phantom consisting of kidney cortex, renal capsule, ureter, adrenal gland, muscle, fat, and skin is used. Four stages of renal cancer tumors are considered depending upon the tumor size in each stage. The presence of a tumor causes an increase in the reflection coefficient (S ₁₁ ) and a shift in resonance frequency, which can be used to identify cancer. The increase in reflection coefficient and the shift in resonance frequency are calculated for each stage of the cancer tumors. The shift in resonance frequency for the early stages is too small. Therefore, detection depends mainly on the increase in S ₁₁ . The shift in resonance frequency and increase in S ₁₁ are large for advanced stages of the tumor, which makes detection easier. Computed specific absorption rate (SAR) is found to be less than the safety levels, which means this technique is safe to use. Overall, this work suggests a new simple detection technique of kidney cancer. The advantages of this technique are: safe, compact, fast, inexpensive, comfortable examination, non-invasive, and finally non- ionizing radiation during measurement.

Antennas in wireless sensor networks (WSNs) are characterized by the enhanced capacity of the network, longer range of transmission, better spatial reuse, and lower interference. In this paper, we propose a planar patch antenna for mobile communication applications operating at 1.8, 3.5, and 5.4 GHz. A planar microstrip patch antenna (MPA) consists of two F-shaped resonators that enable operations at 1.8 and 3.5 GHz while operation at 5.4 GHz is achieved when the patch is truncated from the middle. The proposed planar patch is printed on a low-cost FR-4 substrate that is 1.6 mm in thickness. The equivalent circuit model is also designed to validate the reflection coefficient of the proposed antenna with the S₁₁ obtained from the circuit model. It contains three RLC (resistor–inductor–capacitor) circuits for generating three frequency bands for the proposed antenna. Thereby, we obtained a good agreement between simulation and measurement results. The proposed antenna has an elliptically shaped radiation pattern at 1.8 and 3.5 GHz, while the broadside directional pattern is obtained at the 5.4 GHz frequency band. At 1.8, 3.5, and 5.4 GHz, the simulated peak realized gains of 2.34, 5.2, and 1.42 dB are obtained and compared to the experimental peak realized gains of 2.22, 5.18, and 1.38 dB at same frequencies. The results indicate that the proposed planar patch antenna can be utilized for mobile applications such as digital communication systems (DCS), worldwide interoperability for microwave access (WiMAX), and wireless local area networks (WLAN).

In this paper, a technique for the early detection of brain cancer was proposed. The technique depends upon the use of an antenna and a model for the human head. The reflection coefficient (S ₁₁ ) was found for two cases: with and without tumor in the head model. The large increase of S ₁₁ due to the presence of the tumor provides a good indication for tumor detection. It also gives an idea about the size of the tumor. The antenna used was a reconfigurable four-element linear array of squared microstrip patches. Two arrays were designed one circularly polarized, the other linearly polarized. The antenna operates at Industrial Scientific and Medical (ISM) frequency 2.4 GHz. It was designed on FR-4 (lossy) substrate of relative permittivity 4.3 and thickness of 1.6 mm. To feed the array, a corporate feeding network was designed. The reconfigurability of the array was achieved using three single pole double throw (SPDT) switches. Two models of the human head were used; a specific anthropomorphic mannequin (SAM) model, and a 3-D head model consisting of four different head layers: skin, fat, skull and brain. The simulation calculates the reflection coefficient (S ₁₁ ) with and without tumor for circularly polarized (CP) and linearly polarized (LP) linear array. Calculations were taken for four sizes of the array. The best results were obtained with the four-element circularly polarized array. An increase in S ₁₁ of 1188% was obtained. Tumors as small as 5 millimeters (four-layer model) and 2.5 mm (SAM model) can be detected. Specific absorption rate (SAR) was calculated and found to be within the safe limit. A circularly polarized four-element linear antenna array was fabricated. The measured S ₁₁ and radiation pattern are in excellent agreement with simulated ones.

Radio frequency energy harvesting is one of the new renewable sources that faces some technical challenges, which limit its performance. This study presents two scenarios to enhance the harvested power. The first scenario introduces a quad-band voltage multiplier circuit with a single receiving antenna and four band-pass filters of elliptic type. In this scenario, four frequencies of the Global System for Mobile communications, Universal Mobile Telecommunications System, and Wireless Fidelity frequency bands have been considered for the study. The second scenario proposes a quad-band voltage multiplier circuit with four receiving antennas at the same frequency bands as the first scenario. High conversion efficiencies were achieved for the two scenarios. The proposed quad-band system developed a harvested power level, sufficient for powering up low power micro-devices with no need for an external power supply.

Energy scavenging is a promising technique for micro-devices such as wireless sensor networks (WSNs). Radio frequency (RF) is considered a sustainable source that can be utilized and harvested due to its important features. The essential goal of this study was designing and investigating a wide input power range through a theoretical and simulation work for the 900 MHz frequency band with acceptable efficiency. In this work, we investigated both the low input power and the high input power range circuits; the two circuits were combined to achieve the goal of the wide input power range. L impedance matching elements were used to perform the desired matching between the power source and the circuit to reduce the reflected power resulted in enhanced RF-DC conversion efficiency. 60 % was the peak efficiency for the proposed design at 0 dBm with the output voltage of 16.56 V, and a generated current of 1.39 mA for the load of 12KΩ