Array Gain

Array geometry has a significant impact on aperture array design. For large scale array applications such as the Mid-Frequency Aperture Array (MFAA) of the Square Kilometre Array (SKA) telescope, a regular type grid can result in over 20 million array elements to fulfill the sensitivity requirement. Such a fully filled array has an essentially flat effective area with frequency and can provide excellent control of the radiation pattern, particularly the sidelobe level (SLL). Thinning techniques undersample the aperture to reduce the number of elements required, and hence overall system cost, whilst maintaining angular resolution. In principal, the effective area now becomes a function of frequency, depending on the number and type of elements used and their layout. This is also true of sidelobe levels, particularly at wider angular regions. Initially a mathematical model on aperture arrays has been used to develop the thinning algorithms with the goal of exploring how much thinning could be used without significantly effecting the fully filled array performance for a MFAA application. The robustness of the thinning strategy developed is verified by a full wave simulation on finite array using a broadband planar interconnected array approach. This type of array lends itself to economic production of large scale arrays. A thinned array version can in principal be easily implemented although has not been previously reported in the literature. It is confirmed that the total number of elements can be reduced by 7% without a significant impact on overall array performance compared to a fully filled array. Polarization purity is one of the most stringent requirements for future radio telescopes. The polarization performance of the thinned planar array is analyzed including the intrinsic cross polarization ratio and the polarization orthogonality.

Cultural algorithm (CA) is a new evolutionary program inspired by sociology and archaeology theories that assisting formulating cultural evaluation. Its use to solve optimization problems. This paper analyzed the beamforming of a uniform circular antenna array (UCAA) via using the CA algorithm. The sidelobe level (SLL) is minimized by adjusting the appropriate weight for each element. In addition, the optimal beam pattern is achieved by using CA for UCAA, which means that the main beam is steering to the desired user, while the nulls represent the interference signals. The excitation amplitude is supposed to be constant while the elements are assumed isotropic. The circular array number elements and the interspacing distance between them are setting as optimization parameters. The simulation results show that the CA rationally reacts to the changing environments, and it is valuable for SLL reduction. A −25 dB of relative SLL is achieved under beam scanning (0º) and (15º), respectively.

In this paper a way to achieve a virtual two-dimensional planar array for sonar systems using the multiple input multiple output (MIMO) principle is presented. The time delay information of a planar array can be used for imaging sonars and allows the localization of scatterers in three-dimensional space. In a conventional single input multiple output (SIMO) sonar, this would be achieved using a single transmitter and a receiver consisting of a planar array of N² hydrophones, arranged as a rectangular N × N matrix. We show through simulations and experiments how a virtual planar array can be formed using a linear receiver array and linear transmitter array. For this, an experimental MIMO sonar system was constructed with a 32-channel receiver and a 12-channel transmitter, which allowed the realization of a virtual 32 × 12 array. The array design is analyzed through experiment in a harbor basin and through simulations, validating the principle of the virtual planar array. In addition to the experimental investigations, in which only a limited number of transmitter channels are available, further simulations with a 32 × 32 array are performed for further MIMO arrangements to highlight strengths and weaknesses in different application areas.

A communication system is proposed for the Internet of Things (IoT) applications in desert areas with extended coverage of regional area network requirements. The system implements a developed six-element array that operates at a 2.45 GHz frequency band and is optimized to reduce the size and limit element coupling to less than −20 dB. Analysis of the proposed system involves a multiple-input multiple-output (MIMO) operation to obtain the diversity gain and spectral efficiency. In addition, the radiation efficiency of the proposed antenna is greater than 65% in the operation bandwidth (more than 30 MHz) with a peak of 73% at 2.45 GHz. Moreover, an adaptive beamforming system is presented based on monitoring the direction of arrival (DOA) of various signals using the root MUSIC algorithm and utilizing the DOA data in a minimum variance distortionless response (MVDR) technique beamformer. The developed array is found to have an envelope correlation coefficient (ECC) value of less than...

In this paper, a new space-time adaptive processing (STAP) method based on improved nested arrays and pulses configurations is proposed. Specifically, we first decompose the sensor array into two uniform linear arrays (ULAs) plus a separate sensor, similarly for pulse trains. Then, the original received signals from the physical array and pulse trains are introduced into the virtual domain, where the virtual clutter plus noise covariance matrix (CNCM) estimation is performed. Since the system has more virtual sensors and pulses from the perspective of virtual domain, the degrees of freedom (DOF) capability is effectively enhanced to improve the angle and Doppler resolution of radar. With the spatial-temporal smoothing technique, the STAP filter is designed by reconstructing the CNCM and virtual signal steering vector. Simulation results validate the effectiveness and superiority of the proposed algorithm.

Millimeter-wave communication provides highcapacity links for vehicular networks, but it faces challenges such as beam misalignment, rapid topology changes, and energy inefficiency. To address these issues, we propose SA-LS, a 3D hybrid beamforming method that combines simulated annealing (SA) for global optimization with local search (LS) for precise refinement. The method jointly optimizes azimuth, elevation, and complex beamforming weights under realistic vehicular constraints. SA-LS employs an adaptive cooling schedule, stagnationaware restarts, and a Boltzmann-based acceptance criterion to strike a balance between exploration and exploitation. It employs a hybrid beamforming architecture with a uniform planar array (UPA) composed of azimuth and elevation ULAs to form directional beams, with weight normalization. A Hamming window is applied to suppress sidelobes and enhance directivity, and LOS/NLOS awareness enables dynamic beam selection. Simulation results, averaged over multiple vehicular traces, show that SA-LS significantly improves SINR, spectral efficiency, and throughput while reducing path loss, outage probability, beam-switching delay, and energy consumption compared with traditional beamforming and other optimization methods. Index Terms-Adaptive beamforming, millimeter wave (mmWave) communication, simulated annealing (SA), uniform planar array (UPA), vehicular networks.

Successfully achieving the mission of the unmanned aerial vehicle (UAV) requiring a high gain data link between the UAV and the ground control station (GCS). The antenna of the ground station must has a narrow, precisely guided beam towards the UAV. Widening the beamwidth in phased array will be on the expense of reducing the gain and increasing the possibility of receiving the interference signal, this may lead to the failure in achieving the desired link. This paper presents a new method to achieve an automatic forming of the reception beam and automatic tracking of the UAV’s signal in the digital phased array without the need of the complex digital signal processing algorithms used in smart antenna. The proposed approach is based on the complex vector multiplication and phase conjugation technique. The UAV will stay on the beak of the array factor. The resulted array is a combination between retrodirective array and phased array, with beamwidth equal to the field of view without ...

We propose a flexible cluster array concept utilizing diverse antenna elements and the mutual coupling among them to improve the spherical coverage. This innovative approach can not only enhance the impedance matching but also improve the beamforming performance across a wide frequency band by adjusting excitation amplitudes and phases. Equations are derived to achieve specific objectives such as minimizing the total active reflection coefficient or maximizing the realized gain of an antenna array. To validate the concept, we employ a cluster array consisting of eight non-identical patch antenna elements with strong mutual coupling. When compared to a conventional four-element patch antenna array of the same size, the cluster array exhibits high beamforming capability over a wider frequency band. Simulated and measured results confirm that the operational frequency band can be extended from 24.5-26.5 GHz to 24.5-29.5 GHz, while maintaining a spherical coverage of over 6 dBi at the 50%-tile cumulative distribution function (CDF) of maximum realized gain.

To address atmospheric attenuation and path loss issues in the mmwave portion of the spectrum, high gain and narrow beam antenna systems are essential for the next generation communication networks. This paper presents a novel hook-shaped antenna array for 28 GHz 5G mmwave applications. The proposed antenna was fabricated on commercially available Rogers 5880 substrate with thickness of 0.508 mm and dimensions of 10 × 8 mm2. The proposed shape consists of a circle with an arc-shaped slot on top of it and T-shaped resonating lengths are introduced in order to attain broad band characteristics having gain of 3.59 dBi with radiation and total efficiency of 92% and 86% for single element. The proposed structure is transformed into a four-element array with total size of 26.9 × 18.5 mm2 in order to increase the gain up to 10.3 dBi at desired frequency of interest. The four-element array is designed such that it exhibits dual-beam response over the entire band of interest and the simulate...

An Optimization numerical techniques for a very thin wire to find accurate current distribution, input impedance and radiation pattern using Pocklington's integral equation and Hallen's integral equation. However generally the current distribution is usually assumed to be of sinusoidal form finite diameter wires the sinusoidal current distribution is representative accurate. In this techniques both integral equation and some mathematical formulation is being done and shown with help of MATLAB. If we know the voltage at the feed terminals of a wire antenna and find the current distribution, the input impedance and radiation pattern can then be obtained.

Tightly coupled phased arrays (TCPAs) provide UWB performance due to their strong inter-element coupling. However, in finite tightly coupled phased array realizations, mutual coupling is reduced near the array edges, causing the edge elements to become narrowband. To address this issue, a nonuniform array excitation scheme, referred to as "characteristic mode (CM) excitation," was recently proposed. A more practical alternative for designing UWB tightly coupled phased arrays is proposed here. In this paper, we present a strategy that employs uniform excitation of the central array elements and short-circuits the periphery elements. We report that at least for medium size arrays, this approach provides up to 3 dB more gain and 50% higher efficiency than typical resistive termination. This concept is demonstrated using a 7 7 linearly polarized dipole array, 60.96 cm 60.96 cm (2 2 ) in size, for operation from 200 MHz-600 MHz. Feeding of the active elements is challenging due to several constraints on the feed design, including balanced to unbalanced transitions, impedance transformations, common mode suppression, compact size, low cost, etc. To address these issues we propose a novel array feed using a compact, ultrawideband balun (with 10:1 bandwidth for VSWR ). Simulated and measured data are provided for broadside and 30 scan in the H-plane.

The synthesis of pencil beam and arbitrarily shaped beam patterns of linear antenna arrays (LAA) using reduced number of antenna elements attracts the attention of researchers in recent years. In this paper, a hybrid beamforming technique based on the combination of the genetic algorithm (GA) optimization technique and the l 1 minimization method denoted as (GA/l 1 ) is introduced for LAAs synthesis. The proposed GA/l 1 beamforming technique optimizes both the elements excitations and interelement spacing to synthesize the desired LAA pattern with a minimum number of antenna elements. The GA/l 1 technique provides an excellent approximation to the desired radiation pattern with high accuracy and low complexity (less number of iterations and computational time) compared to the other synthesis approaches introduced in the literature. In addition, as an application of this work, the proposed GA/l 1 technique is used to build up a proposed hybrid precoding and beamforming (HP-BF) structure for Massive Multi-input Multi-output (M-MIMO) systems. In this structure, the transmit antenna array is synthesized for maximum gain realization using the existing number of antenna elements. In the HP-BF structure, the proposed GA/l 1 technique is used to make full use of the existing transmit array elements to synthesize the radiation pattern of much larger size and higher gain arrays without the need for additional elements. Thereby, significant savings in the number of antenna elements and their corresponding radio frequency (RF) chains are achieved, which reduces the system complexity. In addition, the array gain maximization will maximize the received signal to noise ratio (SNR) giving rise to higher system performance in terms of spectral efficiency (SE) and power utilization. INDEX TERMS Array synthesis, analog phase shifters, hybrid precoding and beamforming structure, massive multi-input multi-output, millimeter waves, spectral efficiency, uniform linear array.

This letter defines a physical bound based array figure of merit for both single and multi-band array antennas. It provides a measure to compare their performance with respect to return-loss, bandwidth(s), thickness of the array over the ground-plane, and scan-range. The result is based on a sum-rule result of Rozanov-type for linear polarization. For single-band antennas it extends an existing limit for a given fixed scan-angle to include the whole scan-range of the array, as well as the unit-cell structure in the bound. The letter ends with an investigation of the array figure of merit for some wideband and/or wide-scan antennas with linear polarization. We find arrays with a figure of merit > 0.6 that empirically defines high-performance antennas with respect to this measure.

This paper presents a 1 × 4 linear antenna array working at 28 GHz for 5G communication systems. The proposed array employs four rectangular slotted antenna elements fed by a 1 × 4 T-power divider. An artificial magnetic conductor (AMC) layer is placed below the array for increasing the radiation intensity and improving overall array gain. The measured impedance bandwidth of the proposed array with (|S11| < −10 dB) is extended from 25.36 to 26.03 GHz (with a bandwidth of 0.67 GHz) and from 26.75 to 28.81 GHz (with a bandwidth of 2.06 GHz). The proposed array design exhibits a measured gain value that varies between 11.8 dBi and 13.1 dBi within the operating bands and reaches 13.1 dBi at 28 GHz. The proposed array achieves a radiation efficiency of 83.05%, and a front-to-back ratio ranging between 15 and 20 dB across the operating frequency band. The array is fabricated and tested with good matching between the simulated and tested outcomes. The improved performance of the array m...

This paper investigates the focusing features of a multi-panel near-field focused (NFF) antenna. Differently from conventional NFF planar arrays, the proposed configuration is made of a set of NFF subarrays that are concentrically arranged over a cylindrical boundary. A systematic numerical analysis is performed to show how to control the shape of the -3dB focal spot through the main geometrical and electrical parameters of the proposed antenna layout, such as the number of subarrays, the focal spot location of each subarray and the radius of the cylindrical boundary the subarrays are arranged on. When compared with conventional planar NFF arrays, the additional mechanical complexity is partially balanced by a simpler feeding network design and a more symmetric focal spot. Experimental results are shown for a prototype operating at the 2.4 GHz ISM band. INDEX TERMS Antenna arrays, focused arrays, focal spot shaping, near-field communication, near-field focusing, electromagnetic focusing.

The overheads associated with feedback-based channel acquisition can greatly compromise the achievable rates of FDD based massive MIMO systems. Indeed, downlink (DL) training and uplink (UL) feedback overheads scale linearly with the number of base station (BS) antennas, in sharp contrast to TDDbased massive MIMO, where a single UL pilot trains the whole BS array. In this work, we propose a graph-theoretic approach to reducing DL training and UL feedback overheads in FDD massive MIMO systems. In particular, we consider a single-cell scenario involving a single BS with a massive antenna array serving to single-antenna mobile stations (MSs) in the DL. We assume the BS employs two-stage beamforming in the DL, comprising DFT pre-beamforming followed by MU-MIMO precoding. The proposed graph-theoretic approach exploits knowledge of the angular spectra of the BS-MS channels to construct DL training protocols with reduced overheads. Simulation results reveal that the proposed training-resources allocation method can provide approximately 35% sum-rate performance gain compared to conventional orthogonal training. Our analysis also sheds light into the impact of overhead reduction on channel estimation quality, and, in turn, achievable rates.

Smart multiple-input multiple-output (MIMO) antennas with advanced signal processing algorithms are necessary in future wireless networks, such as 6G and beyond, for accurate space division multiplexing and beamforming. Such a MIMO antenna will yield better network coverage and tracking. This paper presents a smart MIMO antenna configuration with a highly innovative beamforming technique using several nonlinear configurations of dipole arrays. Phase delay factors are optimized at the transmitter to form a single beam and then to steer the beam towards a particular direction. A number of phase shifters are added in order to obtain maximum directional gain. This configuration also significantly increases the power gain of the MIMO antenna at a low cost and with operational simplicity. The paper also demonstrates how the beam width and beamsteering can be effectively controlled. Wolfram Mathematica software was used to generate the three-dimensional radiated beam patterns of the transm...

In this paper, we present a comprehensive performance analysis of dual-hop multiple antenna channel state information (CSI) assisted amplify-and-forward (AF) relaying systems over Rayleigh fading channels employing arbitrary transmit antenna selection (TAS) and receiver maximum ratio combining (MRC) with feedback delay in the presence of co-channel interference (CCI) at both the relay and destination. Specifically, an upper bound on the cumulative distribution function (CDF) of the end-to-end signal-to-interference ratio (SIR) is proposed, based on which closed-form expressions for the outage probability and the average symbol error rate (SER) are derived. To gain further insights, simple and high informative expressions for the outage probability and the average SER are obtained at the high SIR regime, which readily enable us to characterize the achievable diversity order and coding gain of the system. Moreover, we present new analytical upper and lower bounds for the ergodic capacity of the system, which apply to the system with arbitrary number of antennas, CCI and feedback delay at any SIRs. Finally, to minimize the outage probability of the system, an optimum power allocation scheme is devised under the total transmission power constraint between the source and the relay. The findings suggest that the feedback delay limits the diversity order to one, while the CCI degrades the outage performance by affecting the coding gain of the system.

The detection performances of an underwater acoustics detection system such as a sonar, can be reduced by self noise phenomena. In this paper, it is shown that the de®nitions of the noise and array gain terms in the sonar equation are related one to the other, and special attention has to be paid to the choice of the reference sensor. A formalism is introduced to take rigorously into account the self noise in the array gain, by splitting the eects of ambient and self noises. The consistency of this formalism with theoretical and experimental results is checked using case studies. For example, it is shown that for a bow-mounted array inside a sonar dome, the array gain behaves like the directivity index, as for a ¯ush-mounted ¯ank array the assumption of uncorrelated noise is more realistic.

In an uncoupled parallel array of bistable dynamical elements subject to a common noisy subthreshold rectangular signal, the signal-to-noise ratio (SNR) gain can be improved by tuning the internally added array noise. A SNR gain above unity is observed in certain regions of the array noise intensity. The maximum SNR gain is obtained as the size of the array goes to infinity. This form of stochastic resonance (SR), i.e., array SR, is analytically described by introducing a quasi-stationary probability density model, yielding expressions for the transition probability and the stationary autocorrelation function. The analytical results have interpretative value for the mechanism of array SR, and may be of heuristic interest for applying array SR to related signal processing problems. Additionally, the analytical descriptions of an isolated bistable system agree well with numerical results of both conventional SR for a subthreshold rectangular input and residual SR for a slightly suprathreshold signal.

This work is concerned with the methodology for improvement of the radiation pattern performance and eliminating the effect of unwanted interference of symmetric time modulated linear antenna array (STMLAA) in the predefined direction. This is achieved using evolutionary technique called Novel Particle Swarm Optimization with Wavelet Mutation (NPSOWM) for various application specific optimization like SLL only reduction, dual broad null and multiple broad null optimization. The optimized results obtained by using NPSOWM are validated by CST-MWS by captivating practical elements of dipole antenna and its array configuration. The numerical results show the effect of the particular (practical) antenna on the array. Various examples have taken for this purpose. A set of 16-element antenna array have designed for SLL only reduction. 16-, 32-, and 64-element STM-LAA for incorporating the dual broad nulls in the angular range from 400 to 700 over the elevation plane. A set of 24-, 30-, and 32-element antenna array have occupied for multiple broad nulls. The strength of the adopted algorithm is tested for different number of array antenna configuration, which establish the efficacy of the optimization technique NPSOWM adopted for achieving the interference cancellation in the predefined direction and performance improvement of the antenna array such as simultaneous improvements of broad nulls (BNs), sidelobe level (SLL), sideband level (SBL), and the directivity. From the simulated results it is clear that NPSOWM can perform better than that of un-optimized linear antenna array with respect to BNs, SLL, and SBLs and Directivity.

| When the di erence of the signal power between multiple interference signals is very large, the conventional adaptive array can't remove all the interference signals e ectively. This causes a slow convergence rate and degrades the performance of the array system. The reason is that the adaptive array adapts only the interference signal having the highest power. In this paper, we propose an improved adaptive array structure from the signal-tointerference-plus-noise ratio SINR point of view. We utilize correlation improvement techniques between the input and the array output signals by controlling the gain of the array output signal. The proposed array called the automatic gain controlled AGC Applebaum array w orks well in multiple interference signals with di erent p o wer levels. We can get the performance improvement of about 25dB in SINR and much faster convergence rate over the conventional one.

Recently, the use of deflecting covering meta-domes for increasing the scanning range of a phased array has been proposed. Although promising, this solution still presents some inherent limitations, such as the significant reduction of the broadside gain compared to the original array, as well as the complexity of the implementation due to the need for a continuous phase profile. This work aims at proposing some technical solutions for maximizing the meta-dome performance and reducing the gain loss at broadside. By properly discretizing and engineering the phase profile along the dome and by taking into account the different angles of incidence onto the meta-cells, we show how it is possible designing realistic meta-domes with reduced insertion loss at broadside, improved steering capabilities, and a reduced profile.

Recently, the use of deflecting covering meta-domes for increasing the scanning range of a phased array has been proposed. Although promising, this solution still presents some inherent limitations, such as the significant reduction of the broadside gain compared to the original array, as well as the complexity of the implementation due to the need for a continuous phase profile. This work aims at proposing some technical solutions for maximizing the meta-dome performance and reducing the gain loss at broadside. By properly discretizing and engineering the phase profile along the dome and by taking into account the different angles of incidence onto the meta-cells, we show how it is possible designing realistic meta-domes with reduced insertion loss at broadside, improved steering capabilities, and a reduced profile.

In this paper we show how phase errors between different analogue signal channels of a phased array affects the quality of the output phased array beam. Specifically we look at the reduction in forward gain of the array beam and the array beam pointing offset as a function of phase errors and array size. We use a combination of simulations made using the aperture array simulator OSKAR, developed at the University of Oxford, in conjunction with measured results taken from 2-PAD; a functioning, astronomical, dual-polarisation, digital beamforming, 4 × 4 element, aperture array prototype (Greenwood 2007) for the Square Kilometre Array (Taylor 2007) developed by a consortium of UK universities. We show that phase errors between different signal channels is specifically an important issue for broadband arrays like 2-PAD, and comment on the relative benefit of digital beamforming versus analogue beamforming engines.

We present a practical implementation of a leakywave thinned phased array in printed circuit board (PCB) technology. In this paper, we demonstrate that a reduction of the grating lobes, and therefore an improved gain in a thinned phased array, with respect to standard solutions, is achieved by virtue of the angular filtering introduced by a leaky-wave cavity in the far field. The presented array is designed in PCB and integrated with an inductive partial reflective surface. A full study of the performances of the 7×7 phased array antenna for several scanning angles and frequencies is presented. This paper shows an improved gain, directivity, grating lobe level, back lobe level, beam efficiency, and active reflection coefficient with respect to a reference solution based on 2 × 2 subarrays. The results are validated via the measurements of a 3 × 3 array prototype.

In this paper, a radiating element consisting of a modified circular patch is proposed for MIMO arrays for 5G millimeter-wave applications. The radiating elements in the proposed 2 × 2 MIMO antenna array are orthogonally configured relative to each other to mitigate mutual coupling that would otherwise degrade the performance of the MIMO system. The MIMO array was fabricated on Rogers RT/Duroid high-frequency substrate with a dielectric constant of 2.2, a thickness of 0.8 mm, and a loss tangent of 0.0009. The individual antenna in the array has a measured impedance bandwidth of 1.6 GHz from 27.25 to 28.85 GHz for S11 ≤ −10 dB, and the MIMO array has a gain of 7.2 dBi at 28 GHz with inter radiator isolation greater than 26 dB. The gain of the MIMO array was increased by introducing frequency-selective surface (FSS) consisting of 7 × 7 array of unit cells comprising rectangular C-shaped resonators, with one embedded inside the other with a central crisscross slotted patch. With the FS...

In this paper we show how phase errors between different analogue signal channels of a phased array affects the quality of the output phased array beam. Specifically we look at the reduction in forward gain of the array beam and the array beam pointing offset as a function of phase errors and array size. We use a combination of simulations made using the aperture array simulator OSKAR, developed at the University of Oxford, in conjunction with measured results taken from 2-PAD; a functioning, astronomical, dual-polarisation, digital beamforming, 4 × 4 element, aperture array prototype (Greenwood 2007) for the Square Kilometre Array (Taylor 2007) developed by a consortium of UK universities. We show that phase errors between different signal channels is specifically an important issue for broadband arrays like 2-PAD, and comment on the relative benefit of digital beamforming versus analogue beamforming engines.

In this paper we show how phase errors between different analogue signal channels of a phased array affects the quality of the output phased array beam. Specifically we look at the reduction in forward gain of the array beam and the array beam pointing offset as a function of phase errors and array size. We use a combination of simulations made using the aperture array simulator OSKAR, developed at the University of Oxford, in conjunction with measured results taken from 2-PAD; a functioning, astronomical, dual-polarisation, digital beamforming, 4 × 4 element, aperture array prototype (Greenwood 2007) for the Square Kilometre Array (Taylor 2007) developed by a consortium of UK universities. We show that phase errors between different signal channels is specifically an important issue for broadband arrays like 2-PAD, and comment on the relative benefit of digital beamforming versus analogue beamforming engines.

The significance of high gain directional antennas stems from the need to cope up with the everyday progressing wireless communication systems. Due to low gain of the widely used microstrip antenna, combining multiple antennas in proper geometry increases the gain with good directive property. Over other array forms, this paper uses concentric circular array configuration for its compact structure and inherent symmetry in azimuth. This proposed array is composed of 9 elements on FR-4 substrate, which is designed for WLAN applications at 5.8GHz. Antenna Magus software is used for synthesis, while CST software is used for optimization. The proposed array is designed with optimum inter-element spacing and number of elements achieving a high directional gain of 15.7 dB compared to 14.2 dB of available literature, with a high reduction in side lobe level of-17.6 dB.

Antenna array of large scale have been examined for different applications including 5G technology. To get better data rate or a reliable link substantial number of antenna arrays have been utilized to provide high multiplexing gains as well as array gains with high directivity. In this paper a simple but efficient implementation technique of using sub-arrays for the improvement of large-sized uniform arrays. By repeating a small sub-array multiple times large arrays can be designed. This implication of utilizing small array simplifies the design of a larger array which allows the designer to concentrate on the smaller sub-array before assembling larger arrays. So, by investigating the sub arrays the performance and radiation characteristics of large arrays can be anticipated. The array-factor for a planar sub-array of 2x2 (4 elements) is analyzed using Mat-lab software and then a large array is formed by placing the 2x2 sub-array indifferent configurations in a rectangular arrangem...

5/6G is anticipated to address challenges such as low data speed and high latency in current cellular networks, particularly as the number of users overwhelms 4G and LTE capabilities. This paper proposes a microstrip patch antenna array comprising six radiating patches and utilizing a microstrip line feeding technique to facilitate the compact design crucial for 5G implementation. ROGER 3003, chosen for its advanced and environmentally friendly features, serves as the dielectric material, ensuring suitability for 5G and B5G applications. The designed antenna, evaluated at a resonating frequency of 28.8 GHz with a −10 dB impedance bandwidth of 1 GHz, offers a high gain of 9.19 dBi. Its compact array, cost-effectiveness, and broad impedance and radiation coverage position it as a viable candidate for 5G and future communication applications.

In this paper, the microstrip line fed rectangular patch antenna with inset has been designed and simulated by using ADS software in order to study the effects of various parameters on the antenna's radiation characteristics. Also, two- by-two, four-by-four, eight-by-eight and sixteen-by-sixteen microstrip patch antenna arrays has been discussed. The effect on the antenna parameters due to increasing the antenna elements (array) is observed clearly on antenna gain, directivity. This type of antenna can be used for cellular phones application.

In this work, spatial diversity techniques in the area of multiple-input multiple-output (MIMO) diffusion-based molecular communications (DBMC) are investigated. For transmitter-side spatial coding, Alamouti-type coding and repetition MIMO coding are proposed and analyzed. At the receiver-side, selection diversity, equal-gain combining, and maximum-ratio combining are studied as combining strategies. Throughout the numerical analysis, a symmetrical $2\times 2$ MIMO-DBMC system is assumed. Furthermore, a trained artificial neural network is utilized to acquire the channel impulse responses. The numerical analysis demonstrates that it is possible to achieve a diversity gain in molecular communications. In addition, it is shown that for MIMO-DBMC systems repetition MIMO coding is superior to Alamouti-type coding.

Smart multiple-input multiple-output (MIMO) antennas with advanced signal processing algorithms are necessary in future wireless networks, such as 6G and beyond, for accurate space division multiplexing and beamforming. Such a MIMO antenna will yield better network coverage and tracking. This paper presents a smart MIMO antenna configuration with a highly innovative beamforming technique using several nonlinear configurations of dipole arrays. Phase delay factors are optimized at the transmitter to form a single beam and then to steer the beam towards a particular direction. A number of phase shifters are added in order to obtain maximum directional gain. This configuration also significantly increases the power gain of the MIMO antenna at a low cost and with operational simplicity. The paper also demonstrates how the beam width and beamsteering can be effectively controlled. Wolfram Mathematica software was used to generate the three-dimensional radiated beam patterns of the transm...

For receive-side maximal-ratio combining (MRC) and maximum-average-SNR beamforming (BF), the wirelesschannel fading correlation impacts symbol-detection performance-decreasing correlation improves/degrades MRC/BF performance-whereas the numerical complexity of these methods is fixed-high/low for MRC/BF. Matching signal processing complexity to the actual correlation conditions, and thus to the achievable performance, is possible with a superset of MRC and BF known as maximal-ratio eigencombining (MREC). For imperfectly known and correlated fading gains, new closedform expressions are derived for the probability density function of the MREC output signal-to-noise ratio, as well as for the outage probability (OP) and average error probability. These new expressions permit seamless evaluation for any correlation value of MREC, MRC, and BF performance measures such as the amount of fading, deep-fade probability, diversity and array gains, and OP. Our results confirm that, in realistic scenarios, adaptive MREC can achieve MRC-like performance for BF-like complexity. Index Terms-Adaptive antenna arrays, array gain, channel estimation, diversity gain, eigencombining, Rayleigh fading, Laplacian power azimuth spectrum, lognormal azimuth spread, numerical complexity, statistical beamforming. I. INTRODUCTION S MART-antenna-based wireless communications systems promise tremendous benefits in terms of data rate, user capacity, cell coverage, link quality, and transmitted signal energy [1] [2] [3] [4] [5] [6]. For receive-side smart antennas, two conventional signal processing algorithms are: 1) maximum average signal-to-noise ratio (SNR) beamforming, also referred to as statistical beamforming (BF) [7] [8, Section 9.2.2], whereby the received signal vector is linearly combined with the dominant eigenvector of the correlation matrix of the channel gain vector; and 2) maximal-ratio combining (MRC) [6] [9], whereby the received signal vector is linearly combined with the channel gain vector. BF and MRC are designed for particular spatial fading correlation conditions and only then yield significant performance gains over the single-input single-output (SISO) transceiver. The fading gains on the different received signal branches have to be fully correlated (coherent) for BF, and uncorrelated for MRC [8, Section 9.2.2] [9] [10] [11] [12] [13] [14].

Multi-input Multi-output (MIMO) systems are of the most promising ones in the field of wireless communications as they provide high data rates and reduce the bit error rate (BER) using spatial multiplexing (SM) and diversity gain techniques, respectively. The deep review of MIMO systems shows that most of them are based on the utilization of uniform linear antennas (ULA) arrays. For further performance enhancement, a new digital array beamforming technique for linear antenna arrays optimization is introduced for both singleuser and multi-user MIMO systems to achieve maximum gain. In our proposed technique, the antenna arrays are implemented for a higher gain by adjusting the feeding and the distance between the antenna elements. The modified mathematical model for our proposed digital array beamforming MIMO system has been derived and merged to the current linear detection techniques such as Maximum Likelihood (ML), Zero Forcing (ZF), and Minimum Mean Square Error (MMSE). The simulation results demonstrated the superiority of our proposed technique over the traditional MIMO systems in terms of BER and spectral efficiency (SE).

We present a design of a linear array of tilted dipoles to achieve radiation patterns with asymmetric angular filtering characteristics. To realize the asymmetric radiation, the dipole elements are spaced by a distance larger than half a wavelength, thus allowing for grating lobes to occur in the visible region. Moreover, the dipoles are loaded with artificial dielectrics to increase the front-to-back ratio and consequently to enable higher gain in certain desired angular regions. Based on the design, a linear array with 10 elements is manufactured and tested. The measured results show the ability of such an array to achieve stable gain from broadside up to 90 degrees scanning, while implementing a stop-band angular filter for negative scanning angles.