In this research, a reconfigurable metamaterial (MM) structure was designed using a millimeter-wave (MMW) band with two configurations that exhibit different refractive indices. These two MM configurations are used to guide the antenna’s main beam in the desired direction in the 5th generation (5G) band of 28 GHz. The different refractive indices of the two MM configurations created phase change for the electromagnetic (EM) wave of the antenna, which deflected the main beam. A contiguous squares resonator (CSR) is proposed as an MM structure to operate at MMW band. The CSR is reconfigured using three switches to achieve two MM configurations with different refractive indices. The simulation results of the proposed antenna loaded by MM unit cells demonstrate that the radiation beam is deflected by angles of +30° and −27° in the E-plane, depending on the arrangement of the two MM configurations on the antenna substrate. Furthermore, these deflections are accompanied by gain enhancements of 1.9 dB (26.7%) and 1.5 dB (22.4%) for the positive and negative deflections, respectively. The reflection coefficients of the MM antenna are kept below −10 dB for both deflection angles at 28 GHz. The MM antennas are manufactured and measured to validate the simulated results.

In this article, a new multiband frequency reconfigurable substrate integrated waveguide cavity slot antenna was designed using Computer Simulation Technology software tool for addressing the specific design challenges posed by the internet of things (IoT) based cognitive radio networks. Reconfiguration of frequency bands is achieved using PIN diodes. The antenna resonated at 2.624, 2.664, 2.720, 2.752, 4.304, 4.532, 4.556, 5.236, 5.304, 5.368, 5.332, and 5.392 GHz. The resonant frequency capability and radiation performance are demonstrated by both simulations and measurements. The simulated and measured results were in agreement. The higher efficiency, gain and average bandwidth obtained are 90%, 8.2 dBi and 65 MHz, respectively. The compactness, integrity, reliability, and performance at various operating frequencies make the proposed antenna a good candidate for IoT applications.

The autonomous landing of an unmanned aerial vehicle (UAV) on a moving platform is an essential functionality in various UAV-based applications. It can be added to a teleoperation UAV system or part of an autonomous UAV control system. Various robust and predictive control systems based on the traditional control theory are used for operating a UAV. Recently, some attempts were made to land a UAV on a moving target using reinforcement learning (RL). Vision is used as a typical way of sensing and detecting the moving target. Mainly, the related works have deployed a deep-neural network (DNN) for RL, which takes the image as input and provides the optimal navigation action as output. However, the delay of the multi-layer topology of the deep neural network affects the real-time aspect of such control. This paper proposes an adaptive multi-level quantization-based reinforcement learning (AMLQ) model. The AMLQ model quantizes the continuous actions and states to directly incorporate simple Q-learning to resolve the delay issue. This solution makes the training faster and enables simple knowledge representation without needing the DNN. For evaluation, the AMLQ model was compared with state-of-art approaches and was found to be superior in terms of root mean square error (RMSE), which was 8.7052 compared with the proportional–integral–derivative (PID) controller, which achieved an RMSE of 10.0592.

Cognitive radio (CR) exploits the spectrum efficiently and minimizes the interference between different devices. Meanwhile, multiband frequency-reconfigurable antennas (FRA) are desirable for CR where it is beneficial to dynamically reconfigure a single antenna to be transmitted and/or received on multiple frequency bands. As stated by the literature review, there is a dearth of work into multiband FRA that is directly applied in CR applications with substrate-integrated waveguide (SIW) technology. Frequency-reconfigurable SIW (FRSIW) is seen as promising for the development of microwave and millimeter waveband antennas. This study’s key objective is for the technical operational advances of SIW antennas to be summarized and compared. The design structure of FRSIW elements using different techniques is discussed in detail. The findings supported the effectiveness of FRSIW for managing radio spectrum to work in most efficient way.