Multitude Of Antennas Research Articles

Towards Practical Antenna Selection Based on Multilabel CNN for Large‐Scale MIMO System in an Indoor Scenario

ABSTRACTLarge‐scale multiple input multiple output (MIMO), also known as massive MIMO, serves as a transformative technology that effectively addresses the surging need for data‐intensive applications in the realm of 5G mobile networks and beyond. With a multitude of antennas at its disposal, a large‐scale MIMO base station possesses the capability to concurrently improve by orders of magnitude system spectral and energy efficiencies. Nevertheless, hardware cost and power consumption arise as serious challenge. To circumvent this latter, we investigate the potential of multilabel convolutional neural network (ML‐CNN) to develop an antenna selection (AS) model that based on the available channel state information (CSI) at the transmitter, it dynamically selects the optimal subset of antennas in real‐time. We evaluate the model performance using real indoor channel measurements under three different antenna array configurations. The obtained results demonstrate that the proposed ML‐CNN approach performs similarly to the convex relaxation‐based method, a mathematical technique often used for AS problems that provides optimal solutions with high computation cost, with the advantage of significantly reduced computation time. Moreover, it exhibits strong resilience across various antenna array configurations. Additionally, assessing the ML‐CNN's performance in scenario with imperfect channel estimation confirms its robustness.

UAV-Assisted Wideband Terahertz Wireless Communications with Time-Delay Phased UPA under Beam Squint

Future Unmanned Aerial Vehicle (UAV)-assisted wireless communication systems are expected to utilize wide bandwidths available at terahertz (THz) frequencies to enhance system throughput. To compensate for the severe path loss in the THz band, it is essential to have a multitude of antennas in the UAV to generate narrow beams for directional transmission. However, narrow beams severely limit its spatial coverage, which greatly affects the efficiency of large-scale access UAV-assisted THz systems. Moreover, the combination of massive antennas and large bandwidth at THz makes the misalignment of the beams caused by beam squint non-negligible and also high energy consumption. UAV-assisted communication technology can effectively increase spatial coverage and provide reliable LoS communication links. In addition, reducing the number of radio frequency (RF) chains while ensuring the number of transmitted data streams and space division multiplexing capability is also an effective way to reduce energy consumption in the UAV communication. In this paper, a single RF chain uniform planar array (UPA) with true-time-delays (TTDs) is equipped on the UAV to achieve two dimensional (2D) beams and split spatial beams to improve transmission efficiency. We analyze the 2D beam squint of the UPA and design a time-delay phased UPA for UAV-assisted THz communication systems. By introducing TTDs between the single RF chain and phase shifters, the beam squint can be controlled flexibly by introducing the delay between each antenna. When TTDs are arranged in both the horizontal and vertical dimensions, the coverage of the beams becomes more complicated compared to uniform linear arrays (ULA). Simulation results show that the proposed time-delay phased UPA can achieve better performance in both single-beam and multi-beam modes for single user and multi-user scenarios compared with conventional phased UPA, respectively. In addition, we propose frequency division beam multiple access (FDBMA) multi access technology, which achieves more efficient multi access by reusing resources from different frequency beam pairs. Finally, the results also show that the enlargement of the beamwidth through the proposed FDBMA strategy can also increase the performance in multi-user scenarios.

Application and Optimization of MIMO Communication in Wide Area Monitoring Systems

Multiple-Input Multiple-Output (MIMO) technology uses a multitude of antennas at both transmitter and receiver to transfer a larger data mount simultaneously. It is the key technology in the 4th and 5th communication system generations. In this work, the use of MIMO technology to enhance the data transfer in terms of completeness, correctness and latency in Wide Area Monitoring Systems (WAMS) is envisaged. To further enhance the system, optimization is done to design the communication system in terms of physical layout. A comparison with the state of art technologies is done to highlight how the adoption of the MIMO technology would enhance the data transfer within the smart grid.

Design and Simulation of Tri-Band Active Automotive Antenna

Automotive antenna requirements continue to push for smaller, more integrated solutions while maintaining the high performance expected from modern infotainment and multimedia systems. The multitude of antennas placed inside the car comprises of active antenna systems which is capable of receiving multiband frequency signals for receiver systems. In this work, sensitive circuitry Low Noise Amplifier and slotted rectangular patch antenna together constitutes active antenna systems have been designed and simulated as separate units operating at Tri-Band frequency bands of 833 MHz, 1.892GHz, and 2.772 GHz for Personal Cellular Communication and Direct to Home Satellite Television respectively. These separate design units operating with these frequencies can be integrated as Low Noise Active Integrated Antenna which can be implemented for automotive application.Through simulation we show that the results of the proposed designs are in accordance with Tri-Band frequency operation for specified application.

Pattern synthesis for opportunistic array radar using least square fitness estimation-genetic algorithm method

Pattern synthesis in three-dimensional (3D) opportunistic array radar becomes complex when a multitude of antennas are considered to be randomly distributed in a 3D space. To obtain an optimal pattern, several freedoms must be constrained. A new pattern synthesis approach based on the improved genetic algorithm (GA) using the least square fitness estimation (LSFE) method is proposed. Parameters optimized by this method include antenna locations, stimulus states, and phase weights. The new algorithm demonstrates that the fitness variation tendency of GA can be effectively predicted after several “eras” by the LSFE method. It is shown that by comparing the variation of LSFE curve slope, the GA operator can be adaptively modified to avoid premature convergence of the algorithm. The validity of the algorithm is verified using computer implementation. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011. © 2011 Wiley Periodicals, Inc.

A Brief Perspective on Computational Electromagnetics

There is a growing interest in many quarters in acquiring the ability to predict all manner of electromagnetic (EM) effects. These effects include radar scattering attributes of objects (airplanes, missles, tanks, ships, etc.); the mutal interference of a multitude of antennas on board a single aircraft or ship; the performance of integrated circuits (IC); the propagation of waves (radio and radar) over long distances with the help of hindrance of complicated tomography and ionospheric/atmospheric ducting; and the propagation of pulses through dispersive media (soil, treetops, or concrete) to detect pollutants or hidden targets, or to assess the health of runways. All of the above require extensive computation and, despite the fact that Maxwell`s equations are linear in all these cases, codes do not exist which will do the job in a timely and error-controlled manner. This report briefly discusses how this can be rectified. 16 refs.