BIRDS-1 CubeSat Constellation using Compact UHF Patch Antenna

BIRDS-1 satellites, a constellation of five identical 1U CubeSats, were designed, manufactured, assembled, integrated, and tested at LASINE Laboratory, Kyutech, Japan. Students from five nations (Japan, Ghana, Mongolia, Nigeria, and Bangladesh) collaborated to develop a number of CubeSats with coordinated ground coverage, named “Joint Global Multi-Nation BIRDS,” or abbreviated as “BIRDS.” To establish the downlink communication between satellite and Earth, an UHF patch antenna was utilized. Patch antennas offer an ideal solution to Cube satellite communication requirements due to their compact dimension and lightweight. However, the limited surface area available in CubeSats, conventional UHF and VHF patch antennas cannot be used. In this paper, a compact coaxial fed UHF (437.375 MHz) patch antenna system for 1U BIRDS-1 CubeSat (small satellite) is presented. The proposed antenna consists of a spiral meander line patch at the top side and partial ground plane another side of the substrate. A shorting pin has also been utilized to change the resonance to the required UHF band. For the intended 1U BIRDS-1 application, the goal is to mount on satellite body within a limited area of 1U BIRDS-1 satellite. The proposed antenna dimension (0.105λ×0.047λ×0.002λ at 437.375 MHz) and characteristics are compatible with any CubeSat standard structure. A prototype of the antenna was developed with a 1.57-mm-thick single layer Roger\u27s substrate having a relative permittivity of 2.2, and measured results are consistent with simulation. The proposed UHF antenna has integrated and tested with 1U BIRDS-1 satellite. Finally, the satellite was successfully launched on June 3, 2017, from the John F. Kennedy Space Center, the USA at Low Earth Orbit for earth observations, message relay, space environment, and technology demonstration through the International Space Station

Null Steering of Adaptive Beamforming Using Linear Constraint Minimum Variance Assisted by Particle Swarm Optimization, Dynamic Mutated Artificial Immune System, and Gravitational Search Algorithm

Linear constraint minimum variance (LCMV) is one of the adaptive beamforming techniques that is commonly applied to cancel interfering signals and steer or produce a strong beam to the desired signal through its computed weight vectors. However, weights computed by LCMV usually are not able to form the radiation beam towards the target user precisely and not good enough to reduce the interference by placing null at the interference sources. It is difficult to improve and optimize the LCMV beamforming technique through conventional empirical approach. To provide a solution to this problem, artificial intelligence (AI) technique is explored in order to enhance the LCMV beamforming ability. In this paper, particle swarm optimization (PSO), dynamic mutated artificial immune system (DM-AIS), and gravitational search algorithm (GSA) are incorporated into the existing LCMV technique in order to improve the weights of LCMV. The simulation result demonstrates that received signal to interference and noise ratio (SINR) of target user can be significantly improved by the integration of PSO, DM-AIS, and GSA in LCMV through the suppression of interference in undesired direction. Furthermore, the proposed GSA can be applied as a more effective technique in LCMV beamforming optimization as compared to the PSO technique. The algorithms were implemented using Matlab program

Microwave breast imaging using compressed sensing approach of iteratively corrected delay multiply and sum beamforming

Microwave imaging (MI) is a consistent health monitoring technique that can play a vital role in diagnosing anomalies in the breast. The reliability of biomedical imaging diagnosis is substantially dependent on the imaging algorithm. Widely used delay and sum (DAS)-based diagnosis algorithms suffer from some significant drawbacks. The delay multiply and sum (DMAS) is an improved method and has benefits over DAS in terms of greater contrast and better resolution. However, the main drawback of DMAS is its excessive computational complexity. This paper presents a compressed sensing (CS) approach of iteratively corrected DMAS (CS-ICDMAS) beamforming that reduces the channel calculation and computation time while maintaining image quality. The array setup for acquiring data comprised 16 Vivaldi antennas with a bandwidth of 2.70-11.20 GHz. The power of all the channels was calculated and low power channels were eliminated based on the compression factor. The algorithm involves data-independent techniques that eliminate multiple reflections. This can generate results similar to the uncompressed variants in a significantly lower time which is essential for real-time applications. This paper also investigates the experimental data that prove the enhanced performance of the algorithm. 2021 by the authors. Licensee MDPI, Basel, Switzerland.Acknowledgments: This work was supported by Grant NPRP12S-0227-190164 from the Qatar National Research Fund, a member of Qatar Foundation, Doha, Qatar and the internal grant of Qatar University QUST-1-CENG-2021-6 and the claims made herein are solely the responsibility of the authors. This work was supported by the Ministry of Higher Education of Malaysia (MOHE), grant code No. FRGS/1/2018/TK04/UKM/01/3. This work was supported by Grant NPRP12S-0227-190164 from the Qatar National Research Fund, a member of Qatar Foundation, Doha, Qatar and the claims made herein are solely the responsibility of the authors. Open Access funding provided by the Qatar National Library.Scopu

Design and Optimization of LTE 1800 MIMO Antenna

A multiple input and multiple output (MIMO) antenna that comprises a printed microstrip antenna and a printed double-L sleeve monopole antenna for LTE 1800 wireless application is presented. The printed double-L sleeve monopole antenna is fed by a 50 ohm coplanar waveguide (CPW). A novel T-shaped microstrip feedline printed on the other side of the PCB is used to excite the waveguide’s outer shell. Isolation characteristics better than −15 dB can be obtained for the proposed MIMO antenna. The proposed antenna can operate in LTE 1800 (1710 MHz–1880 MHz). This antenna exhibits omnidirectional characteristics. The efficiency of the antenna is greater than 70% and has high gain of 2.18 dBi

A novel user classification method for Femtocell network by using affinity propagation algorithm and artificial neural network

An artificial neural network (ANN) and affinity propagation (AP) algorithm based user categorization technique is presented. The proposed algorithm is designed for closed access femtocell network. ANN is used for user classification process and AP algorithm is used to optimize the ANN training process. AP selects the best possible training samples for faster ANN training cycle. The users are distinguished by using the difference of received signal strength in a multielement femtocell device. A previously developed directive microstrip antenna is used to configure the femtocell device. Simulation results show that, for a particular house pattern, the categorization technique without AP algorithm takes 5 indoor users and 10 outdoor users to attain an error-free operation. While integrating AP algorithm with ANN, the system takes 60% less training samples reducing the training time up to 50%. This procedure makes the femtocell more effective for closed access operation

Stochastic Leader Gravitational Search Algorithm for Enhanced Adaptive Beamforming Technique.

In this paper, stochastic leader gravitational search algorithm (SL-GSA) based on randomized k is proposed. Standard GSA (SGSA) utilizes the best agents without any randomization, thus it is more prone to converge at suboptimal results. Initially, the new approach randomly choses k agents from the set of all agents to improve the global search ability. Gradually, the set of agents is reduced by eliminating the agents with the poorest performances to allow rapid convergence. The performance of the SL-GSA was analyzed for six well-known benchmark functions, and the results are compared with SGSA and some of its variants. Furthermore, the SL-GSA is applied to minimum variance distortionless response (MVDR) beamforming technique to ensure compatibility with real world optimization problems. The proposed algorithm demonstrates superior convergence rate and quality of solution for both real world problems and benchmark functions compared to original algorithm and other recent variants of SGSA

A Homogeneous Breast Phantom Measurement System with an Improved Modified Microwave Imaging Antenna Sensor

Microwave breast imaging has been reported as having the most potential to become an alternative or additional tool to the existing X-ray mammography technique for detecting breast tumors. Microwave antenna sensor performance plays a significant role in microwave imaging system applications because the image quality is mostly affected by the microwave antenna sensor array properties like the number of antenna sensors in the array and the size of the antenna sensors. In this paper, a new system for successful early detection of a breast tumor using a balanced slotted antipodal Vivaldi Antenna (BSAVA) sensor is presented. The designed antenna sensor has an overall dimension of 0.401λ × 0.401λ × 0.016λ at the first resonant frequency and operates between 3.01 to 11 GHz under 10 dB. The radiating fins are modified by etching three slots on both fins which increases the operating bandwidth, directionality of radiation pattern, gain and efficiency. The antenna sensor performance of both the frequency domain and time domain scenarios and high-fidelity factor with NFD is also investigated. The antenna sensor can send and receive short electromagnetic pulses in the near field with low loss, little distortion and highly directionality. A realistic homogenous breast phantom is fabricated, and a breast phantom measurement system is developed where a two antennas sensor is placed on the breast model rotated by a mechanical scanner. The tumor response was investigated by analyzing the backscattering signals and successful image construction proves that the proposed microwave antenna sensor can be a suitable candidate for a high-resolution microwave breast imaging system

Design of a Miniaturized Meandered Line Antenna for UHF RFID Tags.

A semi-circle looped vertically omnidirectional radiation (VOR) patterned tag antenna for UHF (919-923 MHz for Malaysia) frequency is designed to overcome the impedance mismatch issue in this paper. Two impedance matching feeding strips are used in the antenna structure to tune the input impedance of the antenna. Two dipole shaped meandered lines are used to achieve a VOR pattern. The proposed antenna is designed for 23-j224 Ω chip impedance. The antenna is suitable for 'place and tag' application. A small size of 77.68×35.5 mm2 is achieved for a read range performance of 8.3 meters using Malaysia regulated maximum power transfer of 2.0 W effective radiated power (ERP)

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21 novembre 19341934/11/21 (A63).Appartient à l’ensemble documentaire : PoitouCh