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In active phased-array antennas, the transmit and receive
functions are distributed at the antenna aperture using transmit and
receive (T/R) modules. The use of T/R modules provides a significant
improvement in antenna performance and flexibility in the choice of
array architectures. We present a review of various beamformer
architectures for activ...
Contexts in source publication
Context 1
... of active components, the antenna performance degrades grace- fully as components fail over time. In addition to the T/R modules, the active phased arrays may contain large number of power supplies or dc to dc converters; each dc to dc converter feeds a group of T/R modules. A block diagram of the antenna with these active components is shown in Fig. 8. In Fig. 8, a group of T/R modules share a common control module that houses voltage regulators, drain switches, digital controls, and memory chips. A distributed power system is generally chosen to increase system clutter improvement factor (CIF) [14] and reliability [15]. The choice of beamformer architecture and packaging of ...
Context 2
... components, the antenna performance degrades grace- fully as components fail over time. In addition to the T/R modules, the active phased arrays may contain large number of power supplies or dc to dc converters; each dc to dc converter feeds a group of T/R modules. A block diagram of the antenna with these active components is shown in Fig. 8. In Fig. 8, a group of T/R modules share a common control module that houses voltage regulators, drain switches, digital controls, and memory chips. A distributed power system is generally chosen to increase system clutter improvement factor (CIF) [14] and reliability [15]. The choice of beamformer architecture and packaging of components will ...
Context 3
... this section, we provide guidelines for selecting an active array architecture that maximizes the antenna MTBF. We begin with the phased-array antenna architecture in Fig. 8 and assume that each control module and each power supply drives eight T/R modules. From the maximum allowable number of failures given in Table III for an 8000 element array, we can calculate the antenna MTBF as shown in Table IV for a 3-dB rise in peak ...
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Citations
... This has been extensively studied for phased arrays, in both communication and radar literature [19]. The main difference, however, between a reflective RIS and a phased array radar is that in order to create azimuth-and elevation-difference beams in reception via the latter, separate beamforming architectures are commonly employed [20,21], while on the other hand, a reflective RIS is only able to passively reflect the impinging signals through optimized phase control and does not produce receive beams via dedicated hardware. In a pure RIS-aided communication context, the usual approach is to aim at increasing SNR at the receiver, relying on the estimated cascaded channel responses (i.e., between BS and RIS, and between RIS and UE), or possibly simply based on the prior UE location information (exact or more likely just estimated) [22]. ...
The technology of reconfigurable intelligent surfaces (RISs) has been showing promising potential in a variety of applications relying on Beyond-5G networks. RIS can indeed provide fine channel flexibility to improve communication quality of service (QoS) or restore localization capabilities in challenging operating conditions, while conventional approaches fail (e.g., due to insufficient infrastructure, severe radio obstructions). In this paper, we tackle a general low-complexity approach for optimizing the precoders that control such reflective surfaces under hardware constraints. More specifically, it allows the approximation of any desired beam pattern using a pre-characterized lookup table of feasible complex reflection coefficients for each RIS element. The proposed method is first evaluated in terms of beam fidelity for several examples of RIS hardware prototypes. Then, by means of a theoretical bounds analysis, we examine the impact of RIS beams approximation on the performance of near-field downlink positioning in non-line-of-sight conditions, while considering several RIS phase profiles (including directional, random and localization-optimal designs). Simulation results in a canonical scenario illustrate how the introduced RIS profile optimization scheme can reliably produce the desired RIS beams under realistic hardware limitations. They also highlight its sensitivity to both the underlying hardware characteristics and the required beam kinds in relation to the specificity of RIS-aided localization applications.
... This has been extensively studied for phased arrays, in both communication and radar literature [19]. The main difference, however, between a reflective RIS and a phased array radar is that in order to create azimuth-and elevation-difference beams in reception via the latter, separate beamforming architectures are commonly employed [20], [21]; while on the other hand, a reflective RIS is only able to passively reflect the impinging signals through optimized phase control and does not produce receive beams via dedicated hardware. ...
The technology of reconfigurable intelligent surfaces (RIS) has been showing promising potential in a variety of applications relying on Beyond-5G networks. Reconfigurable intelligent surface (RIS) can indeed provide fine channel flexibility to improve communication quality of service (QoS) or restore localization capabilities in challenging operating conditions, while conventional approaches fail (e.g., due to insufficient infrastructure, severe radio obstructions). In this paper, we tackle a general low-complexity approach for optimizing the precoders that control such reflective surfaces under hardware constraints. More specifically, it allows the approximation of any desired beam pattern using a pre-characterized look-up table of feasible complex reflection coefficients for each RIS element. The proposed method is first evaluated in terms of beam fidelity for several examples of RIS hardware prototypes. Then, by means of a theoretical bounds analysis, we examine the impact of RIS beams approximation on the performance of near-field downlink positioning in non-line-of-sight conditions, while considering several RIS phase profiles (incl. directional, random and localization-optimal designs). Simulation results in a canonical scenario illustrate how the introduced RIS profile optimization scheme can reliably produce the desired RIS beams under realistic hardware limitations. They also highlight its sensitivity to both the underlying hardware characteristics and the required beam kinds in relation to the specificity of RIS-aided localization applications.
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... Radar systems utilize transmission and reception, referred to as a TX/RX radar system [1], to detect targets. The system works by emitting a radar signal from a transmitter, which then bounces off an object and is received by a receiver for target identification and detection. ...
... As heterogeneities in the clock components are inevitable in modern integrated circuitry, adding transmissionand feedback-delay elements and allowing for tunable loop filters and gains can enhance the control of the dynamics and perturbation decay processes in such systems. Defined phase differences between frequency-synchronized clocks, for example, enable beamforming, i.e., spatially focused emission of electromagnetic waves, relevant for communication, audio, and radar applications [56][57][58][59]. A common, spatially distributed time reference with locked phases can be the enabler of precise indoor-navigation systems, as the accuracy of the localization depends directly on the synchrony of the satellite nodes. ...
The production process of integrated electronic circuitry inherently leads to large heterogeneities on the component level. For electronic clock networks this implies detuned intrinsic frequencies and differences in coupling strength and the characteristic time delays associated with signal transmission, processing, and feedback. Using a phase-model description, we study the effects of such component heterogeneity on the dynamical properties of synchronization in networks of mutually delay-coupled Kuramoto oscillators. We test the theory against experimental results and circuit-level simulations in a prototype system of mutually delay-coupled electronic clocks, so-called phase-locked loops. Interestingly, our results show that heterogeneity in the system can actually enhance the stability of synchronized states. That means that beyond the optimizations that can be achieved by tuning homogeneous coupling strengths, time delays, and loop-filter cut-off frequencies, heterogeneities in these system parameters enable much better optimization of perturbation decay rates, stabilization of synchronous states, and tuning of phase differences between the clocks. Our theory enables the design of custom-fit synchronization layers according to the specific requirements and properties of electronic systems, such as operational frequencies, phase relations, and, e.g., transmission delays. These results are not restricted to electronic systems, because signal transmission, processing, and feedback delays are common to networks of spatially distributed and coupled autonomous oscillators.
... Another important objective in engineered or electronic systems is to control the phase relations between the oscillators in synchronized states. This is required for, e.g., "beamforming" and communication-related applications of such electronic oscillators [38][39][40][41]. In the following we discuss a method to control the phase dynamics through tunable heterogeneity in the transmission delays. ...
We study synchronization in networks of delay-coupled electronic oscillators, so-called phase-locked loops (PLLs). Using a phase-model description, we study the collective dynamics of mutually coupled PLLs and report the phenomenon of heterogeneity-induced synchronization. This phenomenon refers to the observation that heterogeneity in the system's parameters can induce synchronization by stabilizing the states which are unstable without such heterogeneity. In systems where component heterogeneity can be tuned and controlled, we show how the complex collective self-organized dynamics can be guided towards synchronized states with specific operational frequencies and phase relations. This is of importance for the technical applicability of self-organized dynamics. In electrical engineering, for example, where components can be strongly heterogeneous, our theoretical framework can inform the design process for networks of spatially distributed PLLs. The results presented here are also useful in understanding the collective dynamics in ensembles of phase oscillators with time-delayed interactions, inertia, and heterogeneity.
... For instance, the so-called multibeams were proposed in [13] to support joint communication and sensing, while in [14], the so-called derivative (i.e., difference) beams from the monopulse radar literature [15] were proposed to support accurate localization, and were later extended to an RIS setting in [16]. The main distinction between a reflective RIS and a phased array radar is that separate beamforming architectures are commonly employed in radar hardware to create azimuth-and elevation-difference beams in reception [17], [18], while a reflective RIS does not produce receive beams via dedicated hardware, and can only passively reflect the impinging signals through optimized phase control. Hence, it is worth investigating how RIS phase profiles can be designed under lookup table constraints to produce difference beams. ...
Smart radio environments (SREs) are seen as a key rising concept of next generation wireless networks, where propagation channels between transmitters and receivers are purposely controlled. One promising approach to achieve such channel flexibility relies on semipassive reflective Reconfigurable intelligent surfaces (RISs), which can shape the bouncing multipath signals for enhancing communication quality of service, making localization feasible in adverse operating conditions, or reducing unwanted electromagnetic emissions. This paper introduces a generic framework that aims at optimizing the end-to-end precoder controlled by RISs, so that arbitrary beam patterns can be generated, given a predefined lookup table of RIS element-wise complex reflection coefficients. This method is validated and illustrated for different targeted beam patterns in both the far-field and the near-field regimes, while considering the prior characterization of real-life RIS hardware prototypes. These results show how, and to which extent, RIS configuration optimization can approximate the desired beams under realistic hardware limitations and low-complexity implementation practicability, or conversely, which RIS elements' lookup tables would be more suitable. The latter can provide useful guidelines for future RIS hardware designs.
... However, they are limited to narrow band applications. Therefore, there is still significant interest in simple, low-loss RF beam formers especially for wide band applications [16]. Yet, the complexity, bulkiness, and high loss of RF beam formers need to be improved. ...
A low-loss electronic beam steering model is presented in this paper based on tightly-coupled dipole array topology for satellite communications applications for K through Ka-band (18-40) GHz. The array is low-profile having < 3.4 mm height and printed on an affordable single-layered PCB. As proof-of-concept, a 4 × 4-element, single polarized array is fabricated and measured showing (18-40) GHz (VSWR < 2) continual band coverage. A compact, low-loss electronic beam steering architecture for moderate bandwidth arrays is also utilized for beam steering. A 2-bits tunable phase shifter, spanning over (18-30) GHz with IL < 2.5 dB, is developed using micro-electro mechanical systems (MEMS) technology. The phase shifter is integrated at the array elements resulting in reduced size, cost, and complexity of the feeding network. A full-wave simulation of the 4 × Infinite array with the integrated MEMS phase shifter is conducted to prove the concept.
... Millimeter-wave (mm-wave) phased arrays designed for 5G networks can serve other needs as well in addition to communications. For example, the state-of-the-art radar systems also utilize phased arrays [1][2][3], and thus, have similar operation principles to the upcoming 5G antennas presented, e.g., in [4][5][6]. Millimeter-wave frequencies are also suitable for imaging purposes, since the small wavelength enables higher spatial resolution in the image reconstruction. ...
This paper presents a recent progress in a millimeter-wave imaging done with a potential 5G base-station phased-array antenna exhibiting frequency-diverse, non-focused beams. The presented imaging system operates in 24–32 GHz band and is the first realization where phased arrays primarily developed for 5G communications are utilized in a frequency-diverse imaging application. The image reconstruction method solves the linear inverse problem with an iterative algorithm, and several images have been reconstructed based on the measurement data. Currently, a metallic sphere can be successfully located in the target space. However, future work is still required, and the paper further discusses the possibilities and restrictions of the current imaging setup.
... Аналіз останніх досліджень та публікацій Розробці методів розрахунку надійності АФАР присвячено декілька праць зарубіжних та вітчизняних авторів [2][3][4][5][6][7][8][9][10][11]. ...
... У працях професора А. К. Агравала [2][3][4] розглядається розрахунок надійності АФАР за критерієм допустимого погіршення рівня бічних пелюсток. У праці [2] досліджується надійність АФАР, представленої матрицею на 8000 елементів зі значенням амплітуди головної бічної пелюстки розподілу Тейлора, рівному 40 дБ і гексагональною структурою розміщення випромінювачів, відстань за елементами якої становить половину довжини хвилі. ...
... Such a model should take into consideration energy parameters of the modules and their elements, dependence of efficiency (and operating temperature) on the output power level, dependence of temperature on the design parameters of the cooling system, a more accurate description of module failure rate based on analysis of failure rate of module elements. A model of reliability of a single-level APAA of a multifunctional RS was developed in [7,8]. A formula for calculating the meantime-between-failures (MTBF) of the antenna array was proposed. ...
A generalized probabilistic-physical model of reliability of a two-level active phased antenna array (APAA) of a multifunctional radar station was presented.
When constructing the APAA physical model, definitions of failures of the radiating channel and the antenna array as a whole were formulated. Key parameters of the APAA were chosen: radiation power, gain in transmission and the top level of the near side lobes. This has made it possible to formulate generalized criteria of failure of the APAA operating in the modes of transmission and reception as well as determine the permissible number of failures of the radiating channels and receiving modules. The physical model of the APAA reliability was formalized by a system of equations describing deviation of key parameters of the antenna array beyond the permissible limits. At the same time, boundary (permissible) values of the number of failed radiating channels and receiving modules were found that provide critical (minimum permissible) values of key parameters of the antenna array.
To construct a probabilistic model of the APAA reliability, the antenna array was defined as an isotropic hierarchical system and a formula was derived for determining the average number of operable radiating channels in the multi-level APAA structure. A block-diagram of reliability of receiving and transmitting sub-arrays, receiving and transmitting APAA has been built and formalized. Definition of failures of the receiving and transmitting sub-arrays, receiving and transmitting APAA was given. This has allowed us to derive analytical expressions for determining mean time to failure, probability of failure-free operation, density of time to failure and failure rates for sub-arrays and the APAA. Exponential distribution (for sudden failures), diffusional non-monotonic distribution (for gradual failures) and composition of exponential and diffusional non-monotonic distributions (at a joint manifestation of sudden and gradual failures) were used as models of failure of SHF elements, transistors, radiating channels and receiving modules. An illustrative example of calculation of the average time to failure of a two-level APAA of a multifunctional RS including 6400 radiating channels was presented.
