This paper presents a multilayered microstrip patch antenna with a semicircle patch with a PEC sheet. First, we investigate the antenna with a single substrate giving the gain value of 6.3dB. Secondly, a double substrate is used in which a metal plate is inserted between both substrates to act as the ground of the antenna and a metal plate is placed on the backside of the lower substrate which acts as a reflector and unfortunately does not improve the gain more than 6.3dB. Furthermore, the gain is enhanced by placing a PEC sheet at ??/4 distance from the antenna. The proposed design covers the frequency band from 5GHz to 6GHz with a maximum gain value of 9.6 dB. The proposed antenna is suitable

for C-band applications.

In this work, the attenuation of the microwave signal is simulated taking into account the terrain features for unmanned aerial vehicles. Mathematical models of microwave signal attenuation have been developed to create radio communication between unmanned aerial vehicles. Comparisons were made between existing methods and the developed method and good agreement was found. Also, for the first time, empirical expressions have been formed that allow taking into account the building factor for calculating signal losses on the route between air and ground unmanned vehicles as part of a mixed group. The developed empirical model is an extension of existing models in the microwave range. Its use makes it possible to simulate the propagation of a radio signal in an urban environment to assess and select the required characteristics of communication systems by unmanned vehicles and calculate the maximum communication range between elements of the air and ground segments of mixed groups of unmanned vehicles.

In this millimeter wave-based wireless positioning study of the 6G communication service, two parameter estimation techniques are proposed to estimate the angle-of-arrival (AOA) parameters of multiple clusters under an indoor 60 GHz millimeter wave positioning channel built in accordance with the IEEE 802. 15. 3c standard specification. It is seen that the proposed weighted-mean AOA estimation technique gives an optimal AOA estimate under a non-line-of-sight (NLOS) condition, as does the proposed mean AOA estimation technique under the line-of-sight (LOS) condition, however the previously published method meets a failure in AOA estimation under the NLOS or LOS condition.

The prototypes of Dual Band Right Hand Circularly Polarized (RHCP) Stacked Microstrip Patch Antennas (SMPA) over the novel Reactive Impedance Surface (RIS) based metasubstrate have been designed, developed and measured exclusively for the Global Navigational Satellite System (GNSS) application. The proposed designs have adopted the multistacked structures of patches over the multistacked substrates. The proposed low-cost dual band antenna-1 achieves 10 dB return loss bandwidths (RLBW) of 2.55% and 11.23%, respectively, for L5 and S band frequencies. The simulated and measured cross-polar discrimination (XPD) values are 21.5 and 15.62 dB, respectively.Which in turn also has wide 3 dB axial ratio beamwidth of 130º and 140º respectively at L5 and S band frequencies. At the corresponding operating frequencies, the simulated and measured RHCP gains are 1.92 dB and 6.25 dB, respectively. Another highly miniaturized dual band antenna-2 has been designed and simulated. It achieves a size reduction of 52.73% compare to antenna-1 along with simulated 10 dB RLBWs of 2.55% and 2.01% at L5 and S band frequencies, respectively. It achieves RHCP gains of 3.1 dB at L5 band frequency and 5.5 dB at S band frequency. The XPD values of 15.92 and 17.58 dB at the targeted frequencies indicate highly effective RHCP operation. The proposed dual band antenna-2 is the most compact size dual band antenna ever reported with miniaturized size of 0.19?0 × 0.19?0 × 0.03?0 for any of GNSS frequency bands.

A folded dipole antenna is made with a microstrip structure that can work at a frequency of 9.02 GHz. This frequency is located in the Super High Frequency (SHF) region. It consists of copper and FR-4. A Reconfigurable folded dipole antenna is made by installing photodiodes on the right and left sides. This photodiode is irradiated with 808 nm, 200 mW infrared light. Based on the simulation results, the working frequency has decreased from 9.02 GHz to 6.60 GHz. However, based on the measured results, the working frequency has increased from 13.859 GHz to 14.851 GHz. Based on these results, the frequency changes between the simulation and measured results are not the same. Next, a resonator is installed on the folded dipole antenna to reduce the error between the simulation and measuring methods. It is because the electromagnetic waves of the antenna can be reflected by the resonator.

Based on the simulation results, the working frequency has decreased from 10.78 GHz to 2.56

GHz. However, based on the measured results the working frequency decreased from 12.510 GHz to 4.861 GHz. In addition, based on the simulation results, gain increased from 2.384 dBi to 4.133 dBi before infrared irradiation and from -2.306 dBi to 2.525 dBi after infrared irradiation. It can be used for 5G applications. 

The free space optical (FSO) links are severely affected by the fog, smoke and thermal gradient which attenuate and disperse optical pulses. This paper shows the analysis of experimental results of the FSO communication link under the influence of atmospheric turbulence and fog in the dedicated atmospheric chamber. A non-coded data using on-off keying (OOK) modulation with the return to zero (RZ) scheme is propagated through the controlled atmospheric chamber and the received signal was analyzed to study the performance of the FSO link. We have proposed an empirical model of the FSO test link which shows a different approach to replicate outdoor atmospheric turbulence and fog effects through a controlled atmospheric environment. The proposed work helps in establishing a practical FSO link having Rytov variance ?????? ranges from 0.016 to 5.012 for weak-to-strong turbulence regimes and attenuation coefficient ???? ranges from 15.2 dB/km to 618.9dB/km for the light to dense fog effects.

In this paper, we have proposed a novel design and simulated an all-optical 1-bit half-adder based on photonic crystal. The fundamental structure is a square lattice of 2D Silicon rods, operating around the central wavelength of 1550 nm. The proposed half adder is composed of an optical combiner with two input ports, A and B are used for excitation power, and two parallel nonlinear ring resonators with two output ports, S and C, which are SUM and CARRY, respectively. In the creation of a nonlinear ring resonators at the resonant wavelength of 1550 nm and 1538 nm, respectively, we replaced the central rods with defect rods made of doped glass with a linear refractive index and nonlinear Kerr coefficient are about 1.4 and 10-14 m2/W. The optical intensity 10 mW/µm2 is used at the input ports A and B. The contrast ratios for output ports SUM and CARRY are about 13.71 dB, 13.67 dB and the total footprint is 198.9 µm2. The proposed structure has the advantage of simple design and small size with dimensions of 15.3×13 µm2. The normalized power values are low which correspond to 0 state in the output, whereas the power is reasonably high at output for logic stat 1, the power level for logic states "0" and "1" is equal to 4% and 94% respectively. The power difference with high and low logic values improves the constant ratios and reduce the bit error rate BER. The finite element method FEM and Plane-wave expansion PWE method are used to simulate the proposed structure under COMSOL Multiphysics software.