This article presents a Phased array antenna employing MEMS Phase shifter. The proposed Phased array antenna consists of eight square patch antennas operating at 10. 4 GHz with a bandwidth of 400 MHz. Feed line for each patch passes through a MEMS Phase shifter realized by a series of bridges above the transmission line. The distance between the bridge and the transmission line underneath it is adjusted using a control signal applied to them, which in turn, introduces a loading effect on the feed signal. This changes the effective length of the feed line and provides Phase shifts with 15-degree resolution. Low loss conversion units are employed in order to couple the Phase shifter and microstrip lines. The integrated numerical analysis approach applied to Phased array antenna employing MEMS Phase shifter and the scattering parameters and radiation patterns at different steering angles demonstrate the effectiveness of employing MEMS Phase shifters in designing Phased array antennas. The proposed design methodology might be applied to other frequency bands, such as millimeter-wave for automotive applications. Employment of MEMS Phase shifters instead of solid-state ones provides high linearity, high power handling, and wide frequency range of operation.

The advancement of technology has significantly increased the importance of defense systems that can scan and identify attacking targets. These systems rely on Phased array antennas to achieve their functionality. The beam remains fixed in a perpendicular orientation without such antennas, preventing effective target detection. Historically, beam rotation was accomplished either mechanically or electronically. Mechanical methods involved the use of levers that required constant rotation, whereas electronic beam rotation was enabled solely by Phased array antennas. This process necessitates the use of Phase shifters, which are typically implemented using either pin diodes or ferrites. In this article, pin diodes are utilized due to their advantages, including high switching speed, reversibility, and superior availability compared to ferrites.rowParametersAmount1Total angle covered45Degree2half power beam width°183Angle change stepLess than 5°4Polarizationlinear5Return Loss (VSWR)Less than 1.56Total weight (antenna, control board, and feeding network)1 kilogram7Dimensions15 cm × 15 cm × 10 mm8Tolerable power1 watt9A(area)126mm10Horn a 35mm11Horn b27mm12horn flare length2inch13C 14Center frequency9.5 G15λ=c/f3× /9.5=31.5 Rather than placing all the PIN diodes on a single unit and rotating the entire antenna pattern to the desired angle, this approach proves to be inefficient, as replacing the PIN diodes each time would be impractical. Additionally, constructing such a system would be highly complex. To address these challenges, a more efficient solution involves quantizing the PIN diode Phases into two discrete states: 0° (off) and 180° (on), which are incorporated into a single-bit unit cell with dimensions of 7 × 7. This configuration allows for the beam to be rotated to the desired angle while maintaining system simplicity. However, one important characteristic of this type of antenna is that, as the scanning coverage angle increases, the antenna gain decreases.

In this paper a modified Gaussian pulse stimulus is employed to improve the accuracy of tumor detection inside breast phantom for 2D reconstructed image results in cylindrical setup of the microwave imaging system. This pulse shaping puts more energy at higher frequencies in contrast with conventional Gaussian pulse shaping in the impulse radar. Hence a wider bandwidth is available to achieve higher accuracy for precise spatial localization. In the present article a simulated cylindrical setup of the microwave imaging system with a modified stimulated pulse is generated. The main purpose of this paper is employing a new stimulating pulse to detect a tumor from a biological phantom for 2D visualization of time-domain results. In order to achieve the goal, the advantages of generating a novel confocal image-reconstructing algorithm based on back-projection method is employed. The advantage conferred by “ high resolution imaging” is that more energy is used at reflected signal than with conventional confocal imaging, and subsequently a relatively lower spatial resolution in identifying the reflected signal is achieved. Simulated results are presented to validate the effectiveness of the proposed method for precisely calculating the time-dependent location of targets.

A new four elements compact antenna array is presented and discussed to achieve enhanced Phase resolution without sacrificing the array output power. This structure inspired by the Ormia Ochracea’ s coupled ears. The analogy between this insect acute directional hearing capabilities and the electrically compact antenna array is used to enhance the array sensitivity to direction of arrival estimation of an electromagnetic wave. This four elements biomimetic compact array is composed of four strongly coupled antenna elements and two external coupling networks which are designed to enhance the Phase resolutions between all antenna element outputs without decrease in the array output power. In other words, this four elements compact array extracts the same power level from the incident EM wave compared with regular array, while the output Phase sensitivity is significantly enhanced. The simulation results confirm the advantages of this new compact array compared with the previously reported ones in the literature.

Flight systems, have extensive applications in various scientific, industrial, and commercial fields. One component utilized in flight systems' structure is radar. In various applications of these systems, it is required to track specific targets and directions in a narrow angular region. This feature is achievable by utilizing the narrow beam-width antennas. array antennas, besides providing the demanded gain, can fulfill such requirement. Also, the beam-width should be tunable in an acceptable range of different directions. Such a tunability can be realized using the Phased array antennas. The capability of change in main lobe direction of these antennas is provided using the active Phase shifting components as feeders of the Phased arrays, such as PIN diodes and ferrite devices. However, using the passive Butler matrix components is considered as simpler and cheaper tool to realize the approach. Utilizing the Butler matrix with more input-output ports, leads to narrower beam-width radiation pattern. In this paper, a simple design of 32×32 Butler matrix for X-band frequency spectra is proposed, and the simulation results of its performance are presented. The simulations are carried out via Comsol software which is based on finite element method. Finally, after applying the appropriate waves to two specific input ports and connecting the Butler matrix structure to the microstrip array, the beam-width of 3. 5 degrees is achieved. The achievement to narrow beam width radiation realized by a microstrip antenna array fed with a 32×32 Butler matrix and only based on a single layer board, is the main purpose of the research.

The main purpose of this article is to evaluate and to compare the performance metrics, array factor (AF), signal to interference plus noise ratio (SINR), mean square error (MSE), bit error rate (BER), and also computational complexity of different modified blind adaptive beamforming algorithms based on constrained constant modulus (CCM).Two modified algorithms use adaptive step size mechanisms in the stochastic gradient (SG) algorithm for adjusting the step size. The third one, CCM-RLS, uses recursive least squares (RLS) optimization algorithm which is replaced by the inverse correlation matrix instead of the step size. In the case of a uniform linear array (ULA) and 5 users, one as desired signal and the others as interference signals, simulation results show that the modified algorithms, CCMRLS, CCM-SG-time averaging adaptive step size (TAASS) and CCM-SG-modified adaptive step size (MASS), offer higher performance with respect to conventional CCM-SG, respectively. Comparing the performance of CCM-RLS and adaptive step size versions of CCM-SG show that CCM-RLS converges faster and it can cancel the interferences close to the desired signal, more effectively. Moreover, the resulting SINR level is higher and BER is less than the other methods.However, CCM-SG-MASS and CCM-SG-TAASS have less computational complexity, additions and multiplications.

Numerical investigation has been made on a linear array of surface wave driven plasma monopole antenna using finite difference time domain simulation. Variations of the excitation power can be used for construction of a dynamically reconfigurable antenna. Plasma elements in the nominal pressure of 0.4 mb are fed through an RF power at 500 MHz using an equal power divider. The results show that while the variations of the excitation power shift the array resonant frequency between 50 MHz to 120 MHz, the array gain and directivity remain approximately unchanged in the new resonant frequency. Since efficiency is critical to communication systems, the total efficiencies of the reconfigurable array were analyzed from the least to the highest excitation power. The highest efficiency belongs to the array which the separation between elements is a quarter of wavelength. Using this cutting edge technology in space application, it will be possible to transmit through an antenna in a multiple frequency avoiding interference between adjacent antennas.

Biogeography based optimization (BBO) is a new stochastic force based on the science of biogeography.Biogeography is the schoolwork of geographical allotment of biological organisms. BBO utilizes migration operator to share information between the problem solutions. The problem solutions are known as habitats and sharing of features is called migration. In this paper, BBO algorithm is developed to optimize the current excitations of concentric circular antenna arrays (CCAA). Concentric Circular antenna array (CCAA) has numerous attractive features that make it essential in mobile and communication applications. The goal of the optimization is to reduce the side lobe levels and the primary lobe beam width as much as possible. To confirm the capabilities of BBO, three different CCAA antennas of different sizes are taken. The results obtained by BBO are compared with the Real coded Genetic Algorithm (RGA), Craziness based Particle Swarm Optimization (CRPSO) and Hybrid Evolutionary Programming (HEP).

High-gain antennas are crucial for ensuring stable communication in imaging and remote sensing satellites due to their ability to support high data transmission rates while compensating for the limitations associated with increasing transmitter power or reducing transmission rates. Various antenna types, including electromechanical pointing structures, planar Phased array antennas, and conformal Phased array antennas, are employed for high-resolution image transmission and communication with ground stations. In satellite communication systems, small-gain omnidirectional antennas typically exhibit a significant gain of 15 dBi. Among these, the conical structure maximizes effective area, while the polyhedral pyramidal structure is also highly effective. An X-band patch antenna was designed and subjected to full-wave simulation using CST software to enhance performance. The designed antenna achieved a peak gain of 5.64 dBi at 8.45 GHz. The antenna array configuration includes eight patch antennas mounted on each face of a polyhedral array, with power distributed via an 8-way Wilkinson power divider. The resulting array achieved a gain of 14.3 dBi, by array theory principles. The construction of a polyhedral conformal array yielded a maximum gain of 18.3 dBi, with consistent gains exceeding 15 dBi for elevation angles beyond 30°. A high-gain circularly polarized array antenna was specifically engineered for satellite system applications, ensuring a robust and effective design and construction. A triangular planar array facilitates the development of various conformal array configurations, making it well-suited for satellite applications.

In this article, the synthesis of the two-dimensional radiation pattern of multi-beams in the time-modulated planar antenna array is discussed. With the aim of reducing the time of numerical calculations of multi-beam synthesis and eliminating the traditional and optimization approaches, which are mostly complicated and time-consuming, the convolutional neural network approach has been investigated. In this study, the simultaneous shaping of multiple beams as desired in the time modulated antenna array is presented for the first time. By using the method of switching elements and their time modulation, which is based on the Chabi-Sheff distribution, to use and realize multi-beams such as the fundamental beam and the first and second harmonics with low side lobe level and steering at different spatial angles, create various random data. After that patterns and modulations like them are stored. After that, by presenting and designing a model of the convolutional neural network, learning the model for the relationship between the main beam pattern and the first two harmonic patterns with the time modulation of each element has been done. The presented neural network has been able to learn the relationship between the time modulation parameters of the antenna array elements with the main beam patterns and the first and second harmonics with a mean square error of about 0.03. In order to evaluate this model, a random sample of data has been selected to give its patterns to the input of the network. The output of the network has estimated the time modulation sequence of each element. Finally, the modulation pattern of the estimated elements is compared with the main patterns of the comparison and shows the closeness of the original pattern to the estimated pattern. This method provides a good capability for arbitrary control of multiple beams for applications that require establishing multiple connections.