Number Of Phase Shifters Research Articles

Reduction of Phase Shifters in Planar Phased Arrays Using Novel Random Subarray Techniques

Reducing the number of phase shifters by grouping antenna elements into subarrays has been extensively studied for decades. The number of phase shifters directly affects the cost, complexity, and power consumption of the system. A novel method for the design of phased planar antenna arrays is presented in this work in order to perform a reduction of up to 70% in the number of phase shifters used by the array, while maintaining the desired radiation characteristics. This method consists of creating fusions of subarrays to generate random sequences that form the best feeding network configuration for planar phased arrays. The obtained solution allows scanning the mainlobe at θ=−40∘ elevation with a range of scanning of [−75∘<ϕ<75∘] in the azimuth plane, while maintaining a side lobe level below −10 dB and achieving a reduction of 62% in the number of phase shifters. It is shown that each solution is created based on search criteria, which influence the morphology of the array in terms of subarray size and orientation. The proposed methodology shows great flexibility for creating new phased antenna array designs that meet the requirements of specific applications in a short period of time.

Aperture-Coupled Beam-Scanning Patch Array With Parasitic Elements Using a Reconfigurable Series-Fed Phase-Shifting Structure

In this letter, we propose a reconfigurable series-fed phase-shifting structure with movable metal plate for active millimeter wave beam-scanning application. The proposed phase-shifting structure can be equivalent to a certain number of phase shifters in the series-fed network. It can be easily controlled with only one metal plate, which further simplify the design of control system for phase shifters and reduce the cost. A prototype of 1-D aperture-coupled patch array with parasitic elements at 28GHz is designed, fabricated and measured for verifying the performance of the proposed phase-shifting structure. The measurement results at 28 GHz show 1-D beam-steering capability with maximum steering angle of ∼22 deg at H-plane can be achieved, revealing great potentials for developing the simple control and cost-effective active phased array for millimeter wave wireless power transmission application.

Double-Phase-Shifter Based Hybrid Beamforming for mmWave DFRC in the Presence of Extended Target and Clutters

In millimeter-wave (mmWave) dual-function radar-communication (DFRC) systems, hybrid beamforming (HBF) is recognized as a promising technique utilizing a limited number of radio frequency chains. In this work, in the presence of extended target and clutters, a HBF design based on the subarray connection architecture is proposed for a multiple-input multiple-output (MIMO) DFRC system. In this HBF, the double-phase-shifter (DPS) structure is embedded to further increase the design flexibility. We derive the communication spectral efficiency (SE) and radar signal-to-interference-plus-noise-ratio (SINR) with respect to the transmit HBF and radar receiver, and formulate the HBF design problem as the SE maximization subjecting to the radar SINR and power constraints. To solve the formulated nonconvex problem, the joinT Hybrid bRamforming and Radar rEceiver OptimizatioN (THEREON) is proposed, in which the radar receiver is optimized via the generalized eigenvalue decomposition, and the transmit HBF is updated with low complexity in a parallel manner using the consensus alternating direction method of multipliers (consensus-ADMM). Furthermore, we extend the proposed method to the multi-user multiple-input single-output (MU-MISO) scenario. Numerical simulations demonstrate the efficacy of the proposed algorithm and show that the solution provides a good trade-off between number of phase shifters and performance gain of the DPS HBF.

A New Generation of Fast and Low-Memory Smart Digital/Geometrical Beamforming MIMO Antenna

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 transmitter antenna. There are two approaches to configure the receiver antenna. In the first approach, the received signal magnitude is maximized by aligning the contribution of all elements of the receiver antenna to the same phase. With this approach, the field gain of the proposed system is 25.52 (14.07 dBi). The signal processing gain at the receiver is 64 (18.06 dBi). Therefore, the overall power gain for this proposed new digital/geometrical smart MIMO system is 32.13 dBi. In the second approach, the receiver beam is directed towards the transmitter by optimizing the phase delay coefficients of the receiver. Here, the overall gain of the system is found to be 134.56 (21.28 dBi). Even though the system gain in the second approach is lower, it has the advantage of low interference at the receiver side.

Real-Valued Optical Matrix Computing with Simplified MZI Mesh

The Mach–Zehnder interferometer (MZI) mesh, a mainstream structure for optical matrix-vector multiplication (MVM), has been widely employed in recently developed optical neural networks (ONNs) and combination optimization problem solvers. The conventional MZI mesh was designed specifically for complex-valued optical MVM. The network includes 2 N 2 phase shifters, and coherent detection is indispensable for retrieving the output complex-valued vectors. Nonetheless, the majority of applications, including ONNs, merely require real-valued optical matrices with N 2 degrees of freedom (DOFs). The DOF gap between the 2 types of matrices results in a severe redundancy in the number of phase shifters when the conventional MZI mesh is applied to implement real-valued optical MVM. In this study, we propose a simplified MZI mesh for performing real-valued incoherent optical MVM. It has N 2 phase shifters and an optical depth of N + 1, and it outperforms the conventional MZI mesh. Furthermore, we constructed an ONN with the proposed MZI mesh and successfully performed the iris classification task via in situ training of particle swarm optimization. More importantly, we introduced a matched on-chip nonlinear activation function, so the proposed MZI mesh can be cascaded onto a single chip. Overall, the proposed real-valued MZI mesh and in situ training method are space efficient, energy efficient, scalable, and robust to fabrication errors. Therefore, they are suitable for large-scale ONNs.

Low-Cost Wide-Angle Beam-Scanning Transmitarray Antennas Using Lens-Loaded Patch Elements: A Proof-of-Concept Study

In this letter, a novel design concept to achieve a low-cost wide-angle beam-scanning transmitarray (TA) using lens-loaded patch (LLP) elements is presented. In this design, each TA element consists of a beam switchable transmitting element, a group of receiving elements, and a signal via. The received powers of a 2×2 subarray are first combined and then transmitted to the corresponding LLP element, where the phases of the transmitted signals are manipulated for beamforming. Compared with the conventional designs, the phase shifters (PSs) can be multiplexed and the number of PSs is effectively eliminated by 75%, which significantly decreases the hardware cost. By employing multiple patches as the feed of the lenses, reconfigurable radiation patterns are obtained, and by properly choosing the transmitting patches, the developed TA achieves a wide-angle two-dimensional beam scanning within ±60° with stable gains. To validate the design concept, passive prototypes with a center frequency of 12.5 GHz are simulated, fabricated, and tested. The measured results show that the aperture efficiency is 30.1%, 19.4%, and 14.1% for beams steered to 0°, 30°, and 60° at 12.5 GHz, respectively. The beam coverage of ±60° with a less than 3.5 dB scanning loss in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane is obtained.

Experimental demonstration of a fast calibration method for integrated photonic circuits with cascaded phase shifters

With the development of research on integrated photonic quantum information processing, the integration level of the integrated quantum photonic circuits has been increasing continuously, which makes the calibration of the phase shifters on the chip increasingly difficult. For the calibration of multiple cascaded phase shifters that is not easy to be decoupled, the resources consumed by conventional brute force methods increase exponentially with the number of phase shifters, making it impossible to calibrate a relatively large number of cascaded phase shifters. In this work, we experimentally validate an efficient method for calibrating cascaded phase shifters that achieves an exponential increase in calibration efficiency compared to the conventional method, thus solving the calibration problem for multiple cascaded phase shifters. Specifically, we experimentally calibrate an integrated quantum photonic circuit with nine cascaded phase shifters and achieve a high-precision calibration with an average fidelity of 99.26%.

An Innovative Way of Using Coherently Radiating Periodic Structures for Phased Arrays With Reduced Number of Phase Shifters

This article presents an innovative design technique for feeding phase antenna arrays using coherently radiating periodic structure (CORPS) technology for reducing the number of phase shifters (PSs) in limited-scan applications with low sidelobe level (SLL). The proposed configuration is implemented taking advantage of the phase interpolation property of a CORPS network of one layer. This configuration is built by interconnecting <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 3$ </tex-math></inline-formula> CORPS networks in a strategic way in order to provide a reduction in the number of PSs while maintaining the scanning capability. Experimental results and full-wave simulations based on CST Microwave Studio reveal that the proposed design technique reduces the recombination losses and generates a better phase slope with respect to the basic CORPS network providing a reduction in the number of PSs. As a novel contribution, this article provides the full antenna system design in order to analyze and study the PSs reduction performance and scanning capabilities of the proposed technique to feed linear antenna arrays. The proposed design technique provides a reduction in the number of PSs for a scanning range of ±25° in linear arrays. The array design model includes the application of the raised cosine amplitude distribution to generate a radiation pattern with minimum SLL. The linear array system was validated by experimental measurements of the full system prototype and full-wave simulations results are provided to verify the accuracy of the array model and to take mutual coupling into account. The proposed case provides a good design compromise with respect to other cases in the state of the art.

Optimization of antenna array pattern for uniformly excited rectangular array via a thinning method

Antenna arrays have various applications, such as radar, military systems, and wireless communications. The performance of the communication system depends heavily on the antenna array design process. The major challenges in designing such arrays are the high sidelobe levels and the enormous number of elements. Recently, optimization techniques that exploit the evolutionary algorithms have been used extensively for thinning the antenna arrays to reduce power consumption and improve the radiation pattern by decreasing the sidelobe levels. However, due to the stochastic nature of the resolution algorithms, achieving a global optimal for such algorithms is not assured. Based on the combination theory, this paper adopts an element-by-element removing strategy for thinning planar arrays. Without loss of generality, a uniformly excited 25 elements rectangular array with isotropic elements is investigated as an example. The proposed thinning method examines all the possible arrangements of the placements of 25 elements in the phased array aperture. The optimum position of elements is selected to achieve the desired characteristics of the radiation pattern. The results show that with the 40% thinning percentage, the same radiation pattern for the full array (without thinning) can be witnessed. Consequently, a considerable reduction in resource utilization can be achieved in terms of power consumption, the number of phase shifters, and the number of attenuators.

Energy-Efficient Analog Combiner Design Using Low-Resolution Phase Shifters and Antenna Selection for mmWave D2D Communications

This study investigates the use of an analog combiner comprising low -resolution phase shifters (PSs) to suppress interference from other devices and improve the received signal power of interest in millimeter-wave device-to-device networks simultaneously. Unlike typical analog combining architectures with PS numbers equaling the number of receiver antennas, the number of PSs in this study is less than that of receiver antennas; this feature saves on equipment costs and improves power efficiency. We jointly optimize the receiver antenna selection and analog combiner design with low-resolution PSs to maximize the spectral efficiency of the resultant device. Because the formulated joint optimization problem is non-convex, we propose a probabilistic evolutionary optimization algorithm with an explicit expression for learning the tilting parameters of the designed sampling distribution. Simulation results demonstrate the excellent performance of the proposed algorithm compared with the semidefinite relaxation approach in terms of spectral and energy efficiency.

Single-Pixel Imaging Using Multimode Fiber and Silicon Photonic Phased Array

Due to the unique nature of offering minimal invasiveness and high spatial resolution simultaneously, multimode fibers (MMFs) are receiving significant attention in bio-imaging applications. While a spatial light modulator is typically used for controlling the wavefront of the light emitted from the MMF, it makes the system slow, bulky, and expensive. To solve this problem, in this work, we demonstrate the use of a chip-scale integrated optical phased array (OPA) for imaging through an MMF. A silicon OPA with 128 independent phase shifters is fabricated and combined with a 3D waveguide interface to generate speckle patterns at the MMF output. Using the generated speckles and the optical power detected by a bucket detector, we experimentally obtain fine 2D images of the target. From the point spread function analysis of the system, the number of resolvable points is derived to be 1007 points, which is much larger than the number of phase shifters.

Beamspace Channel Estimation in mmWave Systems via Cosparse Image Reconstruction Technique

This paper considers the beamspace channel estimation problem in 3D lens antenna array under a millimeter-wave communication system. We analyze the focusing capability of the 3D lens antenna array and the sparsity of the beamspace channel response matrix. Considering the analysis, we observe that the channel matrix can be treated as a 2D natural image; that is, the channel is sparse, and the changes between adjacent elements are subtle. Thus, for the channel estimation, we incorporate an image reconstruction technique called sparse non-informative parameter estimator-based cosparse analysis AMP for imaging (SCAMPI) algorithm. The SCAMPI algorithm is faster and more accurate than earlier algorithms such as orthogonal matching pursuit and support detection algorithms. To further improve the SCAMPI algorithm, we model the channel distribution as a generic Gaussian mixture (GM) probability and embed the expectation maximization learning algorithm into the SCAMPI algorithm to learn the parameters in the GM probability. We show that the GM probability outperforms the common uniform distribution used in image reconstruction. We also propose a phase-shifter-reduced selection network structure to decrease the power consumption of the system and prove that the SCAMPI algorithm is robust even if the number of phase shifters is reduced by 10%.

Random Feeding Networks for Reducing the Number of Phase Shifters in Limited-Scan Arrays

A new phased-array feeding network that results in low sidelobe levels (SLLs) over a limited scan region is demonstrated. The proposed concept groups the individual phased-array elements into random sequences of nonuniform subarrays and employs a single phase shifter (PS) for each subarray. When these random sequences are optimized, the resulting phased array can scan over a wide angle with low SLLs. A methodology for analyzing the random arrays is provided, multiple cases with different numbers of PSs and subarray groups are optimized, and design guidelines are presented. The performance of the random arrays is compared with conventional uniform subarrays and it is shown that random arrays reduce the number of PSs by up to 40% while preserving the same performance. A random array is demonstrated at 7.9 GHz for a 30-element linear design (scan in one direction) with 12 PSs and results in a half-power beamwidth of 4.1° with a scan angle up to ±14° and SLLs less than −15 dB. It is also shown that random arrays can be used in 2-D phased arrays with up to 60% reduction in the number of PSs. Application areas are in low-cost phased arrays with limited scan angles such as automotive radars or landing systems.

A Low-Cost 2 &lt;formula formulatype="inline"&gt; &lt;tex Notation="TeX"&gt;$\times$&lt;/tex&gt; &lt;/formula&gt; 2 Planar Array of Three-Element Microstrip Electrically Steerable Parasitic Array Radiator (ESPAR) Subcells

<?Pub Dtl=""?> A low-cost electrically scanned phased array utilizing microstrip patch electrically steerable parasitic array radiator (ESPAR) subarray cells is presented for the first time. Four single-layer three-element ESPAR subarray cells at one-wavelength spacing are uniformly illuminated by a corporate feed network consisting of microstrip Wilkinson power dividers and ring hybrids. The array is scanned using a combination of ESPAR capacitive mutual coupling control and microstrip switched delay line phase shifters at the subarray level to achieve a scanning range from <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-{\hbox{20}}^{\circ}$</tex></formula> to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$+{\hbox{20}}^{\circ}$</tex></formula> while maintaining high return loss. The ESPAR coupling technique allows a 50% reduction in the number of phase shifters used by utilizing a full wavelength subcell spacing, resulting in excellent performance with inexpensive fabrication. The fabricated prototype exhibits boresight gain of 12.1 dBi with low scan loss and 7.0-dB worst case sidelobe level. The array is compared quantitatively to thinned arrays with and without parasitic elements to illustrate this advantageous technique. A functional prototype is fabricated and measured and is aptly predicted by the full-wave model.

A Novel phased array antenna that uses ferroelectrics and bulk phase shifting

A new concept for phased arrays is proposed using a voltage controlled ferroelectric lens. The ferroelectric lens concept uniquely incorporates bulk phase shifting; the array does not contain individual phase shifters but rather uses ferroelectric material. This will reduce the number of phase shifters from (n × m) to (n + m), where n is the number of columns and m is the number of rows in a phased array. The number of phase shifter drivers and phase shifter controls is also significantly reduced by using row-column beam steering. Thus, the ferroelectric lens concept can potentially lead to low-cost phased arrays. This paper presents the ferroelectric lens concept, theoretical analysis and design, and experimental results. Latest results obtained for C band (4-8 GHz) lens are included. A brief description of ferroelectric materials used for this work is also included

Pattern Nulling By Iterative Phase Perturbation

This paper presents a method for linear array pattern synthesis with multiple suppressed sectors using phase-only control of the antenna elements. Large phase perturbations are obtained by solving the nonlinear problem using an iterative procedure with linear programming. This technique can impose symmetrical and non-symmetrical suppressed sectors in the perturbed pattern. The full phase-only control is accomplished as well as the partial control of the edge elements. The partial control leads to a significant reduction in the number of phase shifters used for sector suppression as compared to the full control implementation.

Pattern Nulling by Iterative Phase Perturbation

This paper presents a method for linear array pattern synthesis with multiple suppressed sectors using phase-only control of the antenna elements. Large phase perturbations are obtained by solving the nonlinear problem using an iterative procedure with linear programming. This technique can impose symmetrical and non-symmetrical suppressed sectors in the perturbed pattern. The full phase-only control is accomplished as well as the partial control of the edge elements. The partial control leads to a significant reduction in the number of phase shifters used for sector suppression as compared to the full control implementation.

Phased array antennas based on bulk phase shifting with ferroelectrics

A new concept for phased arrays is proposed using a voltage controlled ferroelectric lens. The ferroelectric lens concept uniquely incorporates bulk phase shifting; the array does not contain individual phase shifters but rather uses ferroelectric material. This will reduce the number of phase shifters from (n × m) to (n + m), where n is the number of columns and m is the number of rows in a phased array. The number of phase shifter drivers and phase shifter controls is also significantly reduced by using row-column beam steering. Thus, the ferroelectric lens concept can potentially lead to low-cost phased arrays. This paper presents the ferroelectric lens concept, theoretical analysis and design, and experimental results. A brief discussion of ferroelectric materials is also included.

Concept of an interlaced phased array for beam switching

A novel concept is described for feeding and phasing a large linear array of N antenna elements using only three or five feed points and phase shifters and still achieving beam switching. The idea consists of drastically reducing the number of input points by interlacing a small numer of serially fed subarrays which are suitably phased. This so-called interlaced phased array (IPA) concept was tested using an array of 15 four-element Yagi antennas with a spacing equal to 0.8 wavelengths and found feasible. Some of the distinct advantages of the IPA in comparison with a conventional system of beam switching are reduced power loss, reduced phasing errors, reduced cost, increased reliability resulting from greatly reduced number of phase shifters, and better symmetry of off-zenith beams. >

Design for steering accuracy in antenna arrays using shared optical phase shifters

Uniform linear phased arrays where many radiating elements share a relatively small number of phase shifters are investigated. Such architectures arise in arrays which derive the time delays in the signal paths from a small group of independent phase shifters. In particular, a true time-delay device which has been suggested recently for optically controlled arrays is used as the basic phase shifter. Different architectures, viz. alternative procedures of deriving the necessary time delay for each antenna in the face of phase-shifter inaccuracies, are examined. The variance of the steered beam's direction is used as the performance criterion. The direction-optimal architecture is obtained by means of quadratic programming, and is shown not to be unique. The nonuniqueness of the optimal architecture is exploited to improve other characteristics of the array's beam shape, and the optimal solution is shown to compare favorably with a suboptimal interleaved solution which is easier to implement. >