Progressive Phase Shift Research Articles

Rigorous design and experimental validation of non-reciprocal bandpass filter with ultrawide high reverse isolation bandwidth

This work presents a rigorous design and experimental validation of a non-reciprocal bandpass filter (NBPF) employing time-modulated resonators with progressive phase shift sinusoidal modulation signal to achieve low forward transmission insertion loss (IL) and ultrawide high reverse isolation bandwidth. Analytical design equations have been derived for numerical design of NBPF asl well as providing insights of nonreciprocal frequency response. Additionally, these proposed analytical spectral S-parameters offer the flexibility to design NBPFs with arbitrary termination port impedances. This work also demonstrates a systematic approach to find modulation parameters without relying on optimization methods. It has established empirical relationships between the modulation parameters and the filters specifications to achieve low forward transmission IL and reverse isolation exceeding 15 dB at entire frequency range. The accuracy of the proposed NBPF design has been confirmed by comparing with harmonic balance simulation results of microstrip line NBPF. For experimental validation, three prototypes of NBPF with different termination port impedances are designed, implemented, and manufactured. In experimental results, the frequency of NBPFs can be continously tuned from 1.62 GHz to 1.94 GHz (17.98 %) with maximum forward transmission IL (|S21|) of 5.40 dB and input/output return loss higher than 12 dB. For each frequency tuning state, the reverse isolation (|S12|) exceeds higher than 20 dB across the entire frequency range.

The Design and Implementation of a Phased Antenna Array System for LEO Satellite Communications.

LEO satellite constellations can provide a viable alternative to expand connectivity to remote, isolated geographical areas and complement existing IoT terrestrial communication infrastructures. This paper aims to improve LEO satellite communications by implementing a new phased antenna array system that can significantly improve the radio communication link's performance. By adjusting the progressive phase shift to each element of the antenna array system, the direction of the main radiation lobe of the phased antenna array system can be controlled with accuracy. As far as we know, it is the first time that a four-element, three-quarter wavelength phased antenna array system has been successfully realized with the intention of being optimized for implementation in LEO IoT satellite reception systems. The proposed system's high level of performance is confirmed by the measurements, which indicate effective control of the main radiation lobe orientation. The numerical analysis shows a maximum gain close to 12 dBi for about 42° elevation, a Half Power Beamwidth (HPBW) of 32° in the vertical plane, and 80° in the azimuth plane. The experimental measurement results at various main lobe orientation angles revealed an HPBW ranging from 76° to 87° in the azimuth plane and a maximum Front-to-Back ratio (F/B) of 14.5 dB.

Non-Magnetic Non-reciprocal Bandpass Filter with Quasi-Elliptic Response and Tunable Center Frequency

This paper presents a detailed analytical numerical design methodology and experimental validation of non-magnetic non-reciprocal bandpass filter (NBPF) that exhibits a highly selective quasi-elliptic response in forward direction of propagation. By modulating resonators with progressive phase shift AC modulation signal, unidirectional RF signal propagation (|S21| ≠ |S12|) is achieved. Analytical spectral S-parameters of the proposed quasi-elliptic NBPF have been derived to gain insight nonreciprocal response. Furthermore, empirical relationships between modulation parameters and filter specifications have also been established through numerical simulations, allowing for simplified design process of the NBPF. By varying the resonant frequency of the resonators, a frequency reconfigurable transfer function can be achieved, providing center frequency tunability of NBPF. For experimental validation purposes, a prototype of microstrip line NBPF is designed and manufactured using three time-modulated resonators, which are implemented using transmission line loaded with varactor diodes. The passband frequency can be continuously tuned by changing DC-bias voltage of varactor diodes. The measurement results revealed that passband center frequency is tuned from 1.65 GHz to 1.95 GHz achieving at tuning ratio of 1.182:1, while maintaining the nonreciprocal behavior with two transmission zeros. For all tuning states, in-band minimum insertion loss in forward direction was measured between 3.20 and 4.8 dB, whereas isolation in reverse direction was measured up to 34.5 dB.

A Compact Broadband 4×4 Butler Matrix With 360° Continuous Progressive Phase Shift

This article presents a novel compact broadband <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \ttimes 4$</tex-math> </inline-formula> Butler matrix with 360 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> continuous progressive phase shift. The tunable Butler matrix is composed of a typical <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \ttimes 4$</tex-math> </inline-formula> Butler matrix and four wideband continuously tunable phase shifters (PSs). To realize the size miniaturization, the right-handed transmission line (RHTL) is employed to construct the compact branch-line couplers and crossovers, which performs well over the operating bandwidth. The size of the proposed Butler matrix utilizing the compact coupler and crossover is reduced about 50% compared with the traditional design. A novel coupled-resonant PS is proposed to realize <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$135^{\circ}\pm10^{\circ}$</tex-math> </inline-formula> continuous phase shift over a wide fractional bandwidth (FBW) of 33.3% (2.0–2.8 GHz). By cascading the miniaturized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \ttimes 4$</tex-math> </inline-formula> Butler matrix and the 135 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> continuously tunable PSs, 360 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> continuous progressive phase shift between four outputs can be obtained. The measured results verify the feasibility of the design.

Multiorder Harmonic Analysis of Time-Varying Media Using Time-Domain Simulation

This work puts forth a simple time-domain simulation technique, applicable to periodically space-time-modulated nanophotonic systems, whereby the electromagnetic fields associated with any harmonic order may be extracted in the time, space, and frequency domains. The technique uses existing time-domain simulation tools to run multiple simulations of the same system but with a progressive global phase shift between the source- and time-modulation signals. The fields associated with any desired harmonic order are obtained by particular linear combinations of the ensuing simulation results. To illustrate, the method is applied to the finite-difference time-domain simulation of a sinusoidally space–time-modulated surface conductivity and to a sinusoidally space–time-modulated coupled nanocavity system. The accuracy of the technique is confirmed by showing good agreement between numerical results and theoretical models. Until now, multiharmonic analysis could be done only with frequency-domain simulation methods.

Analyzing and Optimizing the EIRP of a Phase-Tunable Amplifier-Antenna Array

We analyze the performance of an amplifier-antenna array by using separately measured amplifier load-pull data and antenna S-parameters and port-specific radiation patterns. We show that the effective isotropic radiated power (EIRP) of the system can be improved by using phase values which differ from progressive phase shift. Maximum EIRP improvement is 1.1 dB in certain steer directions and over 0.5 dB improvement over a large beamsteering range was measured when compared to using the progressive phase-shift envelope.

Intra-aortic and Intra-caval Balloon Pump Devices in Experimental Non-traumatic Cardiac Arrest and Cardiopulmonary Resuscitation.

Intra-aortic balloon pump (IABP) use during CPR has been scarcely studied. Intra-caval balloon pump (ICBP) may decrease backward venous flow during CPR. Mechanical chest compressions (MCC) were initiated after 10min of cardiac arrest in anesthetized pigs. After 5min of MCC, IABP (n = 6) or ICBP (n = 6) was initiated. The MCC device and the IABP/ICBP had slightly different frequencies, inducing a progressive peak pressure phase shift. IABP inflation 0.15s before MCC significantly increased mean arterial pressure (MAP) and carotid blood flow (CBF) compared to inflation 0.10s after MCC and to MCC only. Coronary perfusion pressure significantly increased with IABP inflation 0.25s before MCC compared to inflation at MCC. ICBP inflation before MCC significantly increased MAP and CBF compared to inflation after MCC but not compared to MCC only. This shows the potential of IABP in CPR when optimally synchronized with MCC. The effect of timing of intra-aortic balloon pump (IABP) inflation during mechanical chest compressions (MCC) on hemodynamics. Data from12 anesthetized pigs.

Correction to “Synthesizing a uniformly spaced array pattern using integral operator for removing progressive phase shift”

<scp>Correction</scp> to “Synthesizing a uniformly spaced array pattern using integral operator for removing progressive phase shift”

Phased-array antennas using novel PSoC-controlled phase shifters for wireless applications

AbstractThe paper proposes a system consisting of novel programmable system on chip (PSoC)-controlled phase shifters which in turn guides the beam of an antenna array attached to it. Four antennae forming an array receive individual inputs from the programmable phase shifters (IC 2484). The input to the PSoC-based phase shifter is provided from an optimized 1:4 Wilkinson power divider. The antenna consists of an inverted L-shaped dipole on the front and two mirrored inverted L-shaped dipoles mounted on a rectangular conductive structure on the back which resonates in the ISM/Wi-Fi band (2.40–2.48 GHz). The power divider is designed to provide the feed to the phase shifter using a beamforming network while ensuring good isolation among the ports. The power divider has measured S11, S21, S31, S41, and S51 to be −14, −6.25, −6.31, −6.28, and −6.31 dB, respectively at a frequency of 2.45 GHz. The ingenious controller is designed in-house using a PSoC microcontroller to regulate the control voltage of individual phase shifter IC and generate progressive phase shifts. To validate the calibration of the in-house designed control circuit, the phased array is simulated using $s_p^2$ touchstone file of IC 2484. This designed control circuit exhibits low insertion loss close to −8.5 dB, voltage standing wave ratio of 1.58:1, and reflection coefficient (S11) is −14.36 dB at 2.45 GHz. Low insertion loss variations confirm that the phased-array antenna gives equal amplitude and phase. The beamforming radiation patterns for different scan angles (30, 60, and 90°) for experimental and simulated phased-array antenna are matched accurately showing the accuracy of the control circuit designed. The average experimental and simulated gain is 13.03 and 13.48 dBi respectively. The in-house designed controller overcomes the primary limitations associated with the present electromechanical phased array such as cost weight, size, power consumption, and complexity in design which limits the use of a phased array to military applications only. The current study with novel design and enhanced performance makes the system worthy of the practical use of phased-array antennas for common society at large.

SSVEP phase synchronies and propagation during repetitive visual stimulation at high frequencies

Steady-state visual evoked potentials (SSVEPs), the brain response to visual flicker stimulation, have proven beneficial in both research and clinical applications. Despite the practical advantages of stimulation at high frequencies in terms of visual comfort and safety, high frequency-SSVEPs have not received enough attention and little is known about the mechanisms behind their generation and propagation in time and space. In this study, we investigated the origin and propagation of SSVEPs in the gamma frequency band (40–60 Hz) by studying the dynamic properties of EEG in 32 subjects. Using low-resolution brain electromagnetic tomography (sLORETA) we identified the cortical sources involved in SSVEP generation in that frequency range to be in the primary visual cortex, Brodmann areas 17, 18 and 19 with minor contribution from sources in central and frontal sites. We investigated the SSVEP propagation as measured on the scalp in the framework of the existing theories regarding the neurophysiological mechanism through which the SSVEP spreads through the cortex. We found a progressive phase shift from posterior parieto-occipital sites over the cortex with a phase velocity of approx. 8–14 m/s and wavelength of about 21 and 24 cm. The SSVEP spatial properties appear sensitive to input frequency with higher stimulation frequencies showing a faster propagation speed.

A Phase Distribution Network Using 2 × 4 Butler Matrix for Linear/Planar Beam-Scanning Arrays

A new $1\times $ 4 phase distribution network (PDN) featuring a fully controllable progressive phase shift between outputs is proposed for continuous beam-scanning arrays. The PDN is made up of two parts: a modified $2\times $ 4 Butler matrix integrated with four phase shifters (PSs), and a tunable power divider (TPD) whose power division ratio can be controlled over a wide tuning range. The synthesis equations show that the relative phase shift between PDN outputs can be fully controlled by the TPD and embedded PSs without using an external single-pole quad-throw (SP4T) switch. The proposed PDN is demonstrated at 2.4 GHz as the feed network of a 4-element linear array. The experimental results display a fully controllable progressive phase shift (from −180° to 180°) between PDN outputs over a 20% bandwidth with good performance of matching, power division, and relative phase shifts. A spatial coverage of 116° with the feature of continuous beam scanning and negligible dc power consumption is achieved. Benefitting from the single-input topology, a planar 16-element phased array for 2D beam scanning is then realized by simply stacking and cascading five instead of eight PDN modules. It removes the high-cost and bulky SP16T switch. Experimental results demonstrate the uniqueness of the proposed designs.

Multi-beam Antenna Array Operating Over Switch On/Off Element Condition

In this work, is presented the design of a linear multi-beam antenna. The designed procedure is focused on the possibility of switching off a part of antenna array elements, in active antenna systems, in order to preserve resources (power and heat dissipation). The behavior of the original multi beam antenna design is investigated on the radiation pattern alteration due to the switched off elements. The choice of switching on/off antenna elements requires less computational effort from the algorithms incorporated in the active antenna system. Antenna array beam design using progressive phase shifts permits beam orthogonality which is valuable over use multiple beam antenna. In this work, turning off part of antenna elements will inevitably change the beam orthogonality conditions. Despite this, the case presented in this paper, shows beam space discrimination better than 10dB. To rank the behavior of modified antenna, with the turned off elements, are used both Euclidean and Hausdorff distances to measure the changes resulted from the modified array performance. The obtained solutions show the applicability of binary operation on existing antenna array. The metric showed in here can be effectively used as ranking criteria.

Millimeter-Wave Near-Field-Focused Full 2-D Frequency Scanning Antenna Array With Height-Modulated-Ridge Waveguide

A millimeter-wave near-field-focused (NFF) full 2-D frequency-scanning antenna array is presented in this article. The proposed antenna is achieved by combining an NFF ridged-waveguide slot array with a double-layer folded focused progressive feeding network. The linear ridged-waveguide slot array antenna is designed with a height-modulated ridge to focus on the power in one direction. The folded feeding line with different length is used to generate the desired focused phase and frequency-dependent progressive phase shift in the other direction. In this case, as the working frequency is swept in the considered range, the inherent frequency-dependent behavior of the linear NFF leaky-wave antenna (LWA) allows a single-scanning sweep in one direction, whereas the focused progressive feeding network ensures multiple-scanning sweeps in the other direction. A full 2-D electronic scanning with no coverage blindness in the scanning area is achieved. To the best of our knowledge, the proposed NFF antenna array is the first design to achieve the full 2-D scanning focus in the near-field (NF) region only by sweeping the frequency, which means that the testing information in the NF region can be directly obtained with a certain band of frequency. This type of antenna is a good candidate in NF fast-scanning applications, e.g., electromagnetic imaging/detecting systems.

Miniaturized 4 × 4 Butler Matrix and Tunable Phase Shifter Using Ridged Half-Mode Substrate Integrated Waveguide

A novel 4×4 Butler matrix fabricated on ridged half-mode substrate integrated waveguide (RHMSIW) technology is designed and realized. The integration of the proposed Butler matrix with tunable phase shifters fabricated using the same technology is also demonstrated to achieve semi-continuous beam steering for fifth-generation (5G) applications. This article discusses the design considerations of the various ridged half-mode subcomponents of the Butler matrix in detail and presents two novel interconnects, namely 90° waveguide bends and a half-mode open-edge-to-open-edge transition. This article shows that the capacitive ridge on the open edge of one waveguide can be directly connected to the open edge on another with little compromise on the performance over a reference line of the same length. The simulated and measured results of each Butler matrix component are also presented and are all in good agreement. The proposed Butler matrix has a 5% operational bandwidth centered at 3.51 GHz with less than ±22° error in the progressive differential phase shift and less than ±1.2-dB coupling imbalance. Finally, it is shown that the proposed Butler matrix achieves over 70% board area miniaturization in comparison to a similar design fabricated on half-mode substrate integrated waveguide technology.

Synthesizing a uniformly spaced array pattern using integral operator for removing progressive phase shift

In this article, an analytical technique is introduced to obtain the excitation coefficients of uniformly spaced linear antenna arrays in order to achieve a desired array factor. By integration of the prescribed array factor, the array factor dependency to the progressive phase shift is eliminated. A new system of linear equations is consequently obtained whose solution represents the excitation coefficients of the array. Some examples are presented to verify the accuracy of the introduced method. The performance of this strategy is compared with those obtained by the other well-known techniques such as Woodward-Lawson and Fourier transform. It is shown that the presented method estimates the desired array pattern with a very good precision.

Design and simulation of an analog beamforming phased array antenna

In this paper, a phased array antenna is designed and simulated. The antenna array consists of four circularly polarized slotted waveguide elements. The antenna array is simulated using CST MWS. The simulation results for the proposed antenna array at different values of progressive phase shift demonstrate that the S‒parameters for all four ports are less than ‒10 dB over at least 2% bandwidth, the simulated maximum gain is 13.95 dB, the simulated beamwidth can be 19˚ or narrower based on the value of the progressive phase shift. , the range of frequencies over which the simulated Axial Ratio (AR) is below 3 dB is not fixed and varied according to the selected progressive phase shift. The proposed four-element RF front-end is simulated using Advanced Design System (ADS) at operating frequency of 9.6 GHz. The obtained simulation results by ADS indicate the feasibility of implementing the proposed RF-front end for feeding the antenna array to realize analog beamforming.

Secure Wireless Communications Based On Antenna Array Elements

Configuration of antenna array system to offer directional dependent modulation has the capability of enhancing the security level of data transmission against eavesdroppers’ attacks. In this paper, Frequency diverse array (FDA) antenna for physical–layer security in wireless communications has been proposed. The proposed method provide a range and angle dependent directional modulation scheme using FDA with frequency increments to improve physical-layer security point-to-point communications. It maintains the objective of changing the progressive phase shifts at each symbol transmission. Thus the emitted pattern at each symbol transmission period will be range and angle dependent. Consequently, the proposed method offers a robust physical-layer security for wireless transmission, as the transmitted signal will be deliberately distorted along the undesired positions, but can be successfully decoded by the intended receiver position. Numerical results are presented to validate the effectiveness of the proposed method.&#x0D; &#x0D; &#x0D; &#x0D; Keywords: Frequency diverse array; Physical-layer security; Directional antenna modulation; Wireless communication; Range and angle dependent.&#x0D; &#x0D; &#x0D;

A Symmetric Beam-Phased Array Fed by a Nolen Matrix Using 180° Couplers

This letter presents a new microstrip line-phased array using $3 \times 3$ Nolen matrix – with three inputs and three output ports. For each input port excitation, the signal is divided into three equal magnitudes and unique progressive phase shifts at its output ports. The proposed microwave network is composed of three 180° couplers with two of them having identical coupling factors and two microstrip line-phase shifters. To verify the proposed design concept, a prototype of the feeding network working at 5.8 GHz is designed, fabricated, and measured. Both simulation and measurement results are in good agreement with the theoretical prediction.

Medial entorhinal cortex activates in a traveling wave in the rat.

Traveling waves are hypothesized to support the long-range coordination of anatomically distributed circuits. Whether separate strongly interacting circuits exhibit traveling waves remains unknown. The hippocampus exhibits traveling 'theta' waves and interacts strongly with the medial entorhinal cortex (MEC). To determine whether the MEC also activates in a traveling wave, we performed extracellular recordings of local field potentials (LFP) and multi-unit activity along the MEC. These recordings revealed progressive phase shifts in activity, indicating that the MEC also activates in a traveling wave. Variation in theta waveform along the region, generated by gradients in local physiology, contributed to the observed phase shifts. Removing waveform-related phase shifts left significant residual phase shifts. The residual phase shifts covaried with theta frequency in a manner consistent with those generated by weakly coupled oscillators. These results show that the coordination of anatomically distributed circuits could be enabled by traveling waves but reveal heterogeneity in the mechanisms generating those waves.

Novel Design of Slotted Waveguide Phased Array Antenna

A novel design of phased array antenna based on a Slotted Waveguide Antenna Array (SWAA) is introduced in this paper. The CST Microwave Studio simulation results show that the S‒parameters, the gain, the axial ratio, and the beamwidth of the proposed phased array antenna are affected by the value of the progressive phase shift. The simulated results of the proposed phased array antenna at different values of progressive phase demonstrate that the S‒parameters for almost all ports are less than ‒10 dB over at least 2% bandwidth, the simulated phased array antenna gain is above 17 dB in the frequency range from 9.5 GHz to 9.7 GHz, the range of frequencies over which the simulated Axial Ratio (AR) is below 3 dB is not fixed and varied according to the selected progressive phase, the simulated beamwidth can be 6.5˚ or narrower based on the value of the progressive phase shift.