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Today's increase of functions, improvement of performance, and cost reductions required on an active electronically scanned array (AESA), associated to the limited amount of available areas and volumes to implement the equipment, drive an approach leading to directly connect power amplifiers (PAs) to the antennas array without placing an isolator/c...
Citations
... By comparing the above results with what is observed by Refs. [18,35], we can see that the gain of Sc1 and Sc2 shows the range between 38 and 43 dB under 1.004 V biasing, while Ref. [18] used a bias voltage of 7.25 V to achieve a maximum reflection of 30 dB. Furthermore, Refs. ...
... Furthermore, Refs. [18,35] are limited to active RIS elements by using Sc1, while our proposed method gives more flexibility by using biasing voltages to provide different power gains. In this case, the linear amplifier regions and the saturation regions vary with the operation mode of the power amplifier. ...
p> A Reconfigurable Intelligent Surface (RIS) panel comprises many independent Reflective Elements (REs). One possible way to implement an RIS is to use a binary passive load impedance connected to an antenna element to achieve the modulation of reflected radio waves. Each RE reflects incoming waves (incident signal) by using on/off modulation between two passive loads and adjusting its phase using a Phase Shifter (PS). However, this modulation process reduces the amplitude of the reflected output signal to less than unity. Therefore, recent RIS works have employed Reflection Amplifiers (RAs) to compensate for the losses incurred during the modulation process. However, these systems only improve the reflection coefficient for a single modulation state, resulting in suboptimal RE efficacy. Thus, this paper proposes a strategy for optimising RE by continuously activating the RA regardless of the switching load state. The performance of the proposed scheme is evaluated in two scenarios: (1) In the first scenario (Sc1), the RA only operates to compensate for high-impedance loads, and (2) in the second scenario (Sc2), the RA runs continuously regardless of the RE loads. To benchmark the performance of Sc1 and Sc2, various metrics are compared, including signal-to-noise ratio, insertion loss, noise figure, communication range, and power-added efficiency. Numerical examples are provided to demonstrate the effectiveness of the proposed scheme. It is found that the proposed system in Sc2 leads to better overall performance compared to Sc1 due to the increased gain of the RIS reflection.</p
... By comparing the above results with what is observed by Refs. [18,35], we can see that the gain of Sc1 and Sc2 shows the range between 38 and 43 dB under 1.004 V biasing, while Ref. [18] used a bias voltage of 7.25 V to achieve a maximum reflection of 30 dB. Furthermore, Refs. ...
... Furthermore, Refs. [18,35] are limited to active RIS elements by using Sc1, while our proposed method gives more flexibility by using biasing voltages to provide different power gains. In this case, the linear amplifier regions and the saturation regions vary with the operation mode of the power amplifier. ...
A Reconfigurable Intelligent Surface (RIS) panel comprises many independent Reflective Elements (REs). One possible way to implement an RIS is to use a binary passive load impedance connected to an antenna element to achieve the modulation of reflected radio waves. Each RE reflects incoming waves (incident signal) by using on/off modulation between two passive loads and adjusting its phase using a Phase Shifter (PS). However, this modulation process reduces the amplitude of the reflected output signal to less than unity. Therefore, recent RIS works have employed Reflection Amplifiers (RAs) to compensate for the losses incurred during the modulation process. However, these systems only improve the reflection coefficient for a single modulation state, resulting in suboptimal RE efficacy. Thus, this paper proposes a strategy for optimising RE by continuously activating the RA regardless of the switching load state. The performance of the proposed scheme is evaluated in two scenarios: (1) In the first scenario (Sc1), the RA only operates to compensate for high-impedance loads, and (2) in the second scenario (Sc2), the RA runs continuously regardless of the RE loads. To benchmark the performance of Sc1 and Sc2, various metrics are compared, including signal-to-noise ratio, insertion loss, noise figure, communication range, and power-added efficiency. Numerical examples are provided to demonstrate the effectiveness of the proposed scheme. It is found that the proposed system in Sc2 leads to better overall performance compared to Sc1 due to the increased gain of the RIS reflection.
... In this case, the linear amplifier regions and the saturation regions vary with the operation mode of the power amplifier. Typically, it is preferred for the RA to operate at the maximum linear region because its operation in the nonlinear area leads to generating a distortion and harmonics in the output wave [39]. To compare the linearity of Sc1 and Sc2, Fig. 6 depicts the adequate output power (reflected power gain), which is measured by calculating the difference between the output power delivered by the amplifier and the incident power that the amplifier can handle. ...
p>Reconfigurable Intelligent Surface (RIS) panel is composed of many independent Reflected Elements (RE) where one of its possible realisations is based on a binary passive load impedance connected with an antenna element. The received signal at the RE (incident signal) is reflected after adjusting its phase along with a unity (or less) reflection coefficient depending on the selected phase-shifter. Recent RIS works have exploited Reflection Amplifiers (RA) to compensate for the losses incurred in one of the binary phase-shift states, where most of the current active RIS studies rely on the concept of “on/off” RA. Therefore, this paper proposes a strategy for continuously activating the RA to increase the reflected signal power regardless of the selected phase-shifter path. In order to benchmark the performance of the proposed scheme, we evaluate two scenarios for activating the RIS pane; (i) In the first, denoted as Sc1, the RA only works to compensate for high-impudence phase-shifter, and (ii) in the second scenario, denoted as Sc2, the RA runs continuously regardless of the phase-shifter impedance. Different attributes are compared, including Signal-to-noise ratio, insertion loss, noise figure, communication range, and power-added efficiency. To verify the results of the proposed method, an oscillator topology is used to design a practical RA using RF circuit simulation. It is found that the proposed scheme in Sc2 increases the gain of the RIS reflection, which leads to better overall performance than the Sc1 scenario.</p
... In this case, the linear amplifier regions and the saturation regions vary with the operation mode of the power amplifier. Typically, it is preferred for the RA to operate at the maximum linear region because its operation in the nonlinear area leads to generating a distortion and harmonics in the output wave [39]. To compare the linearity of Sc1 and Sc2, Fig. 6 depicts the adequate output power (reflected power gain), which is measured by calculating the difference between the output power delivered by the amplifier and the incident power that the amplifier can handle. ...
p>Reconfigurable Intelligent Surface (RIS) panel is composed of many independent Reflected Elements (RE) where one of its possible realisations is based on a binary passive load impedance connected with an antenna element. The received signal at the RE (incident signal) is reflected after adjusting its phase along with a unity (or less) reflection coefficient depending on the selected phase-shifter. Recent RIS works have exploited Reflection Amplifiers (RA) to compensate for the losses incurred in one of the binary phase-shift states, where most of the current active RIS studies rely on the concept of “on/off” RA. Therefore, this paper proposes a strategy for continuously activating the RA to increase the reflected signal power regardless of the selected phase-shifter path. In order to benchmark the performance of the proposed scheme, we evaluate two scenarios for activating the RIS pane; (i) In the first, denoted as Sc1, the RA only works to compensate for high-impudence phase-shifter, and (ii) in the second scenario, denoted as Sc2, the RA runs continuously regardless of the phase-shifter impedance. Different attributes are compared, including Signal-to-noise ratio, insertion loss, noise figure, communication range, and power-added efficiency. To verify the results of the proposed method, an oscillator topology is used to design a practical RA using RF circuit simulation. It is found that the proposed scheme in Sc2 increases the gain of the RIS reflection, which leads to better overall performance than the Sc1 scenario.</p
... Finally, even if CoSimPy has been developed with the focus on MRI, it can be utilised, as it is, in many other contexts where a two-way link between EM and circuit simulations is needed ( e.g . microwave engineering, hyperthermia, antenna design) [38][39][40][41]. ...
Background and objectives
The Electromagnetic/Circuit cosimulation method represents a valuable and effective strategy to address those problems where a radiative structure has to interact with external supporting circuitries. This is of particular concern for Magnetic Resonance Imaging (MRI), radiofrequency (RF) coils design, where the supporting circuitry optimisation represents, generally, a crucial aspect. This article presents CoSimPy, an open-source Python circuit simulation library for Electromagnetic/Circuit cosimulations and specifically optimised for MRI, RF coils design.
Methods
CoSimPy is designed following an Object-oriented programming. In addition to the essential methods aimed to performed the Electromagnetic/Circuit cosimulations, many others are implemented both to simplify the standard workflow and to evaluate the RF coils performance. In this article, the theory which underlies the fundamental methods of CoSimPy is shown together with the basic framework of the library.
Results
In the paper, the reliability of CoSimPy is successfully tested against a full-wave electromagnetic simulations involving a reference setup. The library is made available under https://github.com/umbertozanovello/CoSimPy together with a detailed documentation providing guidelines and examples. CoSimPy is distributed under the Massachusetts Institute of Technology (MIT) license.
Conclusions
CoSimPy demonstrated to be an agile tool employable for Electromagnetic/Circuit cosimulations. Its distribution is meant to fulfil the needs of several researchers also avoiding duplication of effort in writing custom implementations. CoSimPy is under constant development and aims to represent a coworking environment where scientists can implement additional methods whose sharing can represent an advantage for the community. Finally, even if CoSimPy is designed with special focus on MRI, it represents an efficient and practical tool potentially employable wherever electronic devices made of radiative and circuitry components are involved.
... With a one-tone and two-tone signal description the proposed analysis is capable of predicting the behavior of the entire array antenna. Other techniques such as the application of the non-linear Shimbo model [48], which takes into account the memory effects of the power amplifiers, and other circuit model approaches [49], [50] have been proposed by authors to characterize active array antennas. Nevertheless, such techniques becomes extremely hard to apply to MCMB-driven antennas for several reasons. ...
... In these analytical works, the active components associated with the antenna are known, whereas in MCMB-driven antennas, the particular layout of the utilized IC is unknown. For high-frequency purposes (as in the present work), it becomes extremely difficult to make room for active devices such the ones proposed in some of the references [47]- [50]. Thus, MCMB modules are of great relevance, and an analytical approach of a different active antenna scheme is also discarded. ...
... This way, the performance of the IC in terms of axial ratio would be also tested. An additional research step would be to apply a formal mathematical analysis such as [47]- [50] to the IC that has been used. In this way, the behavior of the IC could be inferred and the active antenna calibration process would be possible. ...
In this paper, a planar active phased array antenna demonstration with linear polarization (LP) at Ka Band (28-30 GHz) is presented. The proof of concept is carried out to evaluate the possible problems that may arise, to analyze possible calibration stages and to assess the viability of the integration of an active system with a Multi-Channel Beamforming Module (MCBM). To fulfill this task an
$8\times 8$
-element planar array arranged in column subarrays of
$1\times 8$
elements for 1D beam steering is proposed. The single element consists of a printed circular patch connected to a microstrip feeding line through metallic vias in a multilayered structure. Both the amplitude and phase distributions are performed by a commercial integrated circuit (IC) designed for transmission purposes, from the common port to each of the 8 output ports. Thus, an evaluation of the IC performance is also included within this work. Despite the inherent amplitude and phase feeding errors of the IC, the beam-steering accuracy of the system is reasonable. A nice correspondence between the simulated and measured
$8\times 8$
-element array beam steering directions is obtained, with errors below 1° in the steering of the beam.
... Each channel of a beamforming IC may include a large number of transistors interacting with adjacent channels in a large array configuration. For these situations, combining PA behavioral models with antenna characteristics is the key to a fast and accurate evaluation of transmitters [14]. A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. ...
... For these situations, combining PA behavioral models with antenna characteristics is the key to a fast and accurate evaluation of transmitters [14]. A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. However, only a limited number of studies have incorporated PA models into active antenna array simulations for evaluating transmitter performance [14], [18]- [22]. ...
... A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. However, only a limited number of studies have incorporated PA models into active antenna array simulations for evaluating transmitter performance [14], [18]- [22]. In [18], an iterative approach has been used to evaluate the active antenna array radiation pattern. ...
div>Hybrid digital and analog beamforming is an
emerging technique for high-data-rate communication at
millimeter-wave (mm-wave) frequencies. Experimental evaluation
of such techniques is challenging, time-consuming, and costly.
This article presents a hardware-oriented modeling method for
predicting the performance of an mm-wave hybrid beamforming
transmitter. The proposed method considers the effect of active
circuit nonlinearity as well as the coupling and mismatch in the
antenna array. It also provides a comprehensive prediction of
radiation patterns and far-field signal distortions. Furthermore,
it predicts the antenna input active impedance, considering
the effect of active circuit load-dependent characteristics. The
method is experimentally verified by a 29-GHz beamforming
subarray module comprising an analog beamforming integrated
circuit (IC) and a 2 × 2 subarray microstrip patch antenna.
The measurement results present good agreement with the
predicted ones for a wide range of beam-steering angles. As a
use case of the model, far-field nonlinear distortions for different
antenna array configurations are studied. The demonstration
shows that the variation of nonlinear distortion versus steering
angle depends significantly on the array configuration and beam
direction. Moreover, the results illustrate the importance of
considering the joint operation of beamforming ICs, antenna
array, and linearization in the design of mm-wave beamforming
transmitters.</div
... Each channel of a beamforming IC may include a large number of transistors interacting with adjacent channels in a large array configuration. For these situations, combining PA behavioral models with antenna characteristics is the key to a fast and accurate evaluation of transmitters [14]. A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. ...
... For these situations, combining PA behavioral models with antenna characteristics is the key to a fast and accurate evaluation of transmitters [14]. A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. However, only a limited number of studies have incorporated PA models into active antenna array simulations for evaluating transmitter performance [14], [18]- [22]. ...
... A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. However, only a limited number of studies have incorporated PA models into active antenna array simulations for evaluating transmitter performance [14], [18]- [22]. ...
div>Hybrid digital and analog beamforming is an
emerging technique for high-data-rate communication at
millimeter-wave (mm-wave) frequencies. Experimental evaluation
of such techniques is challenging, time-consuming, and costly.
This article presents a hardware-oriented modeling method for
predicting the performance of an mm-wave hybrid beamforming
transmitter. The proposed method considers the effect of active
circuit nonlinearity as well as the coupling and mismatch in the
antenna array. It also provides a comprehensive prediction of
radiation patterns and far-field signal distortions. Furthermore,
it predicts the antenna input active impedance, considering
the effect of active circuit load-dependent characteristics. The
method is experimentally verified by a 29-GHz beamforming
subarray module comprising an analog beamforming integrated
circuit (IC) and a 2 × 2 subarray microstrip patch antenna.
The measurement results present good agreement with the
predicted ones for a wide range of beam-steering angles. As a
use case of the model, far-field nonlinear distortions for different
antenna array configurations are studied. The demonstration
shows that the variation of nonlinear distortion versus steering
angle depends significantly on the array configuration and beam
direction. Moreover, the results illustrate the importance of
considering the joint operation of beamforming ICs, antenna
array, and linearization in the design of mm-wave beamforming
transmitters.</div
... Each channel of a beamforming IC may include a large number of transistors interacting with adjacent channels in a large array configuration. For these situations, combining PA behavioral models with antenna characteristics is the key to a fast and accurate evaluation of transmitters [14]. A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. ...
... For these situations, combining PA behavioral models with antenna characteristics is the key to a fast and accurate evaluation of transmitters [14]. A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. However, only a limited number of studies have incorporated PA models into active antenna array simulations for evaluating transmitter performance [14], [18]- [22]. ...
... A variety of PA behavioral models suitable for MIMO and phased array applications has been addressed in the literature [14]- [22]. However, only a limited number of studies have incorporated PA models into active antenna array simulations for evaluating transmitter performance [14], [18]- [22]. In [18], an iterative approach has been used to evaluate the active antenna array radiation pattern. ...
Hybrid digital and analog beamforming is an emerging technique for high-data-rate communication at millimeter-wave (mm-wave) frequencies. Experimental evaluation of such techniques is challenging, time-consuming, and costly. This article presents a hardware-oriented modeling method for predicting the performance of an mm-wave hybrid beamforming transmitter. The proposed method considers the effect of active circuit nonlinearity as well as the coupling and mismatch in the antenna array. It also provides a comprehensive prediction of radiation patterns and far-field signal distortions. Furthermore, it predicts the antenna input active impedance, considering the effect of active circuit load-dependent characteristics. The method is experimentally verified by a 29-GHz beamforming subarray module comprising an analog beamforming integrated circuit (IC) and a 2 times 2 subarray microstrip patch antenna. The measurement results present good agreement with the predicted ones for a wide range of beam-steering angles. As a use case of the model, far-field nonlinear distortions for different antenna array configurations are studied. The demonstration shows that the variation of nonlinear distortion versus steering angle depends significantly on the array configuration and beam direction. Moreover, the results illustrate the importance of considering the joint operation of beamforming ICs, antenna array, and linearization in the design of mm-wave beamforming transmitters.
... Combination of NL/electromagnetic (EM) codesign strategies [4], [5] are possible with commercially available tools, either circuit or full-wave simulators, but they are computationally cumbersome: full-wave analyses are nested inside the HB circuit analysis loop, or foundry models of the linear and of the NL components need be implemented inside the full-wave simulation [6]- [9]. For this reason, the most common approach is to perform the design in two steps. ...
This paper presents the design and characterization of millimeter-wave (28/38 GHz), circularly polarized (CP) active antennas, suitable for the future 5G services. By augmenting the modelling capabilities of commercially available nonlinear CAD tools, the active antenna design can simultaneously optimize figures of merits for both radiation and non-linear (NL) performance. The radiating part is computed and optimized layout-wise by means of an artificial neural network (ANN), suitably trained off-line. For the NL design purpose, the harmonic neural network (HNN) of the antenna is subsequently implemented as a standard circuit component, to include the antenna behavior at all the harmonics of its non-linear regime. This allows avoiding time-consuming EM-simulations in the harmonic balance optimization loop.
In this way, a well-defined interface between the antenna and the amplifier can be avoided. To demonstrate the effectiveness of the design approach, one active AIA, consisting of a class AB amplifier feeding a circularly polarized patch at 38 GHz, has been fabricated with the standard 0.1-μm AlGaAs-InGaAs pHEMT technology and extensively measured with respect to both the electrical and radiation performances. To reduce fabrication costs, a hybrid integration of the antenna and amplifier connection is used, and the antenna is incorporated into the main PCB.
