Wideband Phase Research Articles

Ultra-subwavelength rect-particles for wideband phase velocity equalization in coupled lines

This paper presents a procedural approach for utilizing ultra-subwavelength rectangular chiral particles embedded in the substrate to eliminate the spurious response of the coupled transmission lines by equalizing the even and odd mode phase velocities in a large bandwidth, making it applicable to wideband coupled-line based structures. Even and odd mode phase velocities, is equalized with the BW of 4 GHz, spanning the range 0.5–4.5 GHz, the normalized phase velocity Root Mean Square Error is less than 0.005.

A novel wideband phase shifter on coupled microstrip line

AbstractIn this paper, a new 180° broadband phase shifter with coupled microstrip line with enhanced coupling by etched slots is proposed, which uses the energy coupling between the parallel‐coupled microstrip lines on the upper layer of the dielectric substrate and the etched rectangular slots (RS) structure on the bottom floor to circumvent the problem for achieving wide operating broadband and low insertion loss with compact size and simple structure. First, the main line and the reference line of the proposed phase shifter are composed of two parallel coupled lines and a uniform transmission line, respectively. Then, its working mechanism is described. Afterward, the phase shifter introduced an RS structure to increase the coupling strength, achieving a broadband of 69.7% and very low insertion loss (0.09 dB) with a phase shift of 180 ± 5°. Finally, a prototype 180° phase shifter with a center frequency of 3.0 GHz was designed, fabricated, and measured, and the measured results are good in agreement with the simulated ones.

Analysis and Design of High-Accuracy Driving Circuit for Wideband Phase Modulators

Analysis and Design of High-Accuracy Driving Circuit for Wideband Phase Modulators

A simple 90° hybrid branchline coupler with wideband phase balance for 5G applications

Abstract A 90° hybrid coupler operating at a central frequency of 5.40 GHz is introduced, offering high-performance characteristics with compact dimensions of 616.65 mm² (33.3 mm × 18.5 mm). These features are achieved while maintaining a design that makes it easy to produce. The unique aspect of this microstrip FR4 substrate-based design is the consistent S-parameters, which remain steady despite changes in structural dimensions, thereby making it adaptable to fabrication variations. The reported S-parameters measured in 5.4 GHz are as follows: |S11|= –29.46 dB, |S21|= –4.11 dB, |S31|= –3.96 dB, and |S41|= –21.23 dB. This hybrid coupler operates over a bandwidth of 0.8 GHz (16%), demonstrating remarkable performance within this spectrum. In addition to its design, the coupler exhibits robust resilience against changes in substrate parameters and structural dimensions, ensuring reliability during the fabrication process. Following thorough simulation studies, a physical prototype of the coupler was constructed and subjected to laboratory measurements. The experimental results align closely with the simulation data, validating the accuracy and predictability of the design. In comparison with other studies and designs documented in the literature, this compact, high-performance 90° hybrid coupler exhibits clear advantages in terms of size, isolation, phase deviation, and structural complexity. Therefore, the benefits and applicability of this presented structure in the context of microwave circuits and systems are underscored. It’s noteworthy to mention that the central frequency of 5.4 GHz falls within the sub-6 GHz 5G band range.

A wideband and low-power mm-wave variable-gain phase shifter based on a source-switching scheme

This article presents a low-power and wideband variable-gain phase shifter (VGPS) designed and simulated in a CMOS 65 nm technology. It introduces a source-switching scheme for designing a variable gain amplifier (SSVGA) characterized by invariant linearity, impedance, and phase characteristics, showcasing improved gain and bandwidth compared to conventional VGAs. The current-reuse and staggered-tuning techniques are used to reduce power consumption and extend the bandwidth, respectively. The proposed VGPS enables gain tuning without the need for an additional gain tuning block, resulting in reduced chip area and sidelobe levels in phased array radar systems. The proposed VGPS, with a 5-bit resolution, achieves a 3-dB bandwidth of 18 GHz (53.5–71.5 GHz) and exhibits RMS gain error range from 0.23 to 0.5 dB and RMS phase error range from 0.54° to 2.65° with phase calibration based on simulation results. It achieves a peak average gain of 1.2 dB at 58.5 GHz while consuming a DC power consumption of only 5 mW with a 1.2 V power supply voltage. Moreover, it demonstrates a wide gain tuning of 20.6 dB, allowing for flexible gain adjustments.

High-efficiency Ka-band frequency multiplier based on the nonlinear kinetic inductance in a superconducting microstrip

Local oscillator sources have become a major technological deficit approaching the terahertz frequencies. For applications, where a narrow linewidth is necessary, such as coherent remote sensing, the best solution to signal generation is frequency multiplication, where phase locking can be easily achieved using the fundamental source. We present an alternative to existing frequency multiplier technologies for cryogenic applications. The device is a superconducting waveguide that has kinetic inductance dependent on the rf current through the device. The nonlinear kinetic inductance is anomalous to a nonlinear optical medium, where the Kerr effect causes 3- or 4-wave mixing, as demonstrated in microwave parametric amplifiers utilizing the same nonlinear effect. In 4-wave mixing, three photons at the fundamental frequency are mixed to generate a single photon at the third harmonic. Dispersion engineering is used to achieve wideband phase matching and phase out harmonics higher than the third. The device length is designed to be the point where most photons are up-converted to the third harmonic. Simulations of these devices lead to expected efficiencies as high as 90%. We report results from a NbTiN frequency multiplier from 34.2 to 104 GHz with efficiency better than 50%.

Design of True Time Delay Line Based Octal Transmit Receive Module for Wideband Phased Arrays

Design of True Time Delay Line Based Octal Transmit Receive Module for Wideband Phased Arrays

3-Bit coded metasurface for linear and circular polarized vortex beam broadband modulation based on dual-frequency multistage resonance

A metasurface design scheme is proposed based on reflective double vertical U-shaped resonators. Compared to planar resonators with the same parameters, vertical meta-atom can excite magnetic dipole resonance and quaternary resonance respectively at low and high frequency to achieve stable wideband phase shift and unique free regulation. Vertical meta-atoms can be applied as 3-bit coding elements in linearly polarized (LP) and circularly polarized (CP) states with bandwidths of 0.7–1.1 THZ and 0.55–1.5 THZ, respectively. At the same time, as a half-wave plate, the deflection conversion rate is 95%, the relative bandwidth is 69%, and the operating Angle is 80°. In order to verify the application capability of the designed meta-atom, the excitation and separation of multi-stage vortex beams are performed in the wide frequency range of LP and CP using the coded convolutional addition method. The designed meta-atom only needs to regulate a single structural parameter to fully satisfy the requirements of 3-Bit broadband coding under LP and CP incidence, so it has multi-type polarization wave universality and ultra-wide working bandwidth. Meanwhile, the method can be effectively applied to optical band and microwave band.

A Multioutput and Highly Efficient GaN Distributed Power Amplifier for Compact Subarrays in Wideband Phased Array Antennas

This article presents the design, implementation, and measurement results of a multioutput distributed power amplifier (MODPA) in 100-nm AlN–GaN–AlGaN high-electron-mobility transistor (HEMT) on a silicon substrate. The proposed MODPA improves power-added efficiency (PAE) in distributed amplifiers (DAs) by not wasting reverse traveling waves and delivering all forward and reverse waves to the output ports. Utilizing MODPA in implementing a subarray-based phased-array transceiver reduces the number of power splitters and PAs, significantly reducing the subarray’s chip area and power loss. A design methodology for broadband, efficient amplifier implementation by optimizing load/source impedances at the fundamental and harmonic frequencies is presented based on comprehensive source/load—pull simulations and class-J dynamic load lines. The presented broadband design methodology addresses an ambiguity for picking optimum load/source impedance at a single frequency caused by higher order harmonics of operating frequencies dropping in the band. The fabricated MODPA occupies a 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 3 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> chip area. In 0.01–25-GHz frequency, MODPA delivered 37–41-dBm power to the four outputs, with a 17–21-dB total power gain and 22%–73% total PAE. The power gain and phase variation between the four matched-output ports are less than 1.5 dB and 3 <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> , respectively, making MODPA an attractive design for implementing subarrays.

Design Techniques for L-C-L T-Type Wideband CMOS Phase Shifter with Suppressed Phase Error

In this study, we designed a K-band CMOS switch-type phase shifter. Equivalent circuits of shift and pass modes were analyzed to minimize phase errors in a wide frequency range. In particular, the impedance inside the equivalent circuit of the pass mode was analyzed to derive a frequency region in which the equivalent circuit of the pass mode becomes an L-C-L structure. Based on the fact that equivalent circuits in shift and pass modes can be regarded as L-C-L structures beyond a specific frequency, a design methodology of the wideband phase shifter was proposed through slope adjustment of the phase according to the frequency of each of the two modes. To verify the feasibility of the proposed design methodology, a 20°-bit phase shifter was designed through a 65 nm RFCMOS process. As a result of the measurement at 21.5 GHz to 40.0 GHz, the phase error was within 0.87°.

Bandwidth Enhancement of Comparator Applied in W-Band Circularly Polarized Monopulse Antenna

In this letter, a novel wideband comparator for W-band circularly polarized (CP) monopulse antenna is proposed and analyzed. The comparator mainly consists of four 3 dB waveguide couplers and a novel wideband phase shifter (PS). The bandwidth of the comparator is greatly enhanced by combining the sequential rotation feeding technique with the wideband PS technique for the first time. To verify its wideband performance, the CP monopulse antenna consisting of the comparator and a 2×2 CP horn array is fabricated and measured. The experimental results are in good agreement with the simulation. For the measured sum (Σ) channel, the reflection coefficient lower than -10 dB, the realized gain not less than 11.5 dBi, and the axial ratio (AR) better than 0.45 dB are realized in the whole W-band (75-110 GHz). For the measured azimuth (AZ) and elevation (EL) difference (Δ) channels, the null depths of the difference patterns are less than -25.8 dB at 80, 92.5, and 105 GHz, and the difference patterns are symmetrical and stable.

Compact Bandwidth-Enhanced 180-Degree Phase Shifter Using Edge-Coupled Multi-Microstrip and Artificial Transmission Line.

Compactness has obtained sufficient importance in wideband phase shifter design considerations, as it is directly related to fabrication cost. In this paper, a novel structure was presented to create compact broadband 180-degree phase shifter, which has the advantages of enhanced bandwidth and significantly reduced chip area. The proposed configuration consists of edge-coupled multi-microstrip lines (ECMML) and an artificial transmission line (ATL) with dual-shorted inductors, both of which have the periodic shunt load of capacitors. The ECMML can provide a high coupling coefficient, leading to an increase in the bandwidth, while the introduced capacitors can greatly reduce the line length (35.8% of the conventional method). To verify the relevant mechanisms, a wideband switched network with compact dimensions of 0.67 × 0.46 mm2 was designed via 0.15-micrometer GaAs pHEMT technology. Combined with the measured switch transistor, it was shown that the proposed phase shifter exhibits an insertion loss of less than 2 dB, a return loss of greater than 12 dB, a maximum phase error of less than 0.6° and a channel amplitude difference of less than 0.1 dB in the range of 10 to 20 GHz.

A Low-RCS 2D Multi-Layer Van Atta Array at X-Band

This paper presents a novel approach to reducing radar cross section (RCS) using a 2D multi-layer Van Atta array based on the phase cancellation principle. By controlling the phase of transmission lines using wideband phase shifters, the proposed array can achieve significant RCS reduction at a wide frequency range of 8 GHz to 11 GHz. Both theoretical calculations and experimental measurements were conducted to evaluate the performance of the Van Atta array with phase shifters. Results showed significant RCS reduction from various incident angles, demonstrating the effectiveness of the proposed design in achieving wideband RCS reduction at the X-band.

1-D Wideband Phased Dielectric Resonator Antenna Array With Improved Radiation Performance Using Characteristic Mode Analysis

A 1-D wideband phased array of the rectangular ring dielectric resonator antenna (RRDRA) is presented for millimeter-wave applications. By using the characteristic mode analysis, it is found that the unwanted higher order mode (HOM) of the RRDRA results in severe gain degradation and high cross polarization when the array scans. To remedy the problem, each RRDRA is loaded with a pair of silver strips. They can suppress the unwanted HOM and enable good scanning performance in a wide frequency range. To demonstrate the idea, a 1×4 phased RRDRA array was designed, fabricated and measured for the licensed millimeter-wave bands (24.25–29.5 GHz). Reasonable agreement between the measured and simulated results is observed.

Orthogonal Adjacent-Order Filtering Element-Based Wideband Transmissive Linear-to-Circular Polarization Converter

This article proposes a unified design method for a highly efficient wideband transmissive linear-to-circular polarization converter composed of two orthogonal adjacent-order bandpass filtering elements for the first time. First, the linear-to-circular polarization converter is constructed to convert two orthogonal linearly polarized (LP) spatial waves split from a 45°-slant incident plane wave into a desired circularly polarized (CP) wave. Taking advantage of the wideband filter synthesis method and phase shifter theory, polarization converter elements with prescribed specifications [e.g., fractional bandwidth (FBW) and Chebyshev passband ripple] are then synthesized by the corresponding low-characteristic-impedance bandpass filtering networks with the loading of shunt short-circuited stubs on quarter-wavelength transmission line (TL) sections. The adjacent-order phase difference function with a natural ±90° value at a center frequency can be simultaneously manipulated by a filtering bandwidth. The theoretical axial ratio (AR) curve is calculated by the synthesized magnitude responses and phase deviation (PD) function. The design guideline is then summarized. Finally, based on the third- and fourth-order bandpass filtering networks, a prototype of the proposed linear-to-circular polarization converter operating at 5 GHz with a designable 70% 3 dB AR bandwidth is implemented, fabricated, and tested by the free-space measurement method. The transmitted CP wave with three in-band AR minima and relatively stable angular performances can be efficiently converted from the incident LP spatial wave as well verified in the experiment. The AR curves and design requirements of different adjacent-order bandpass filtering combinations are further explored according to the proposed design guideline.

Sensitivity optical non-linear measurement based on wide-band phase objects

On the basic that the phase object (PO) is the key optical device in the 4f imaging system, a modified high sensitivity optical nonlinear measurement technique with an absorptive homemade phase object (HPO) is reported in order to characterize the value of weak nonlinear refraction material. The absorptive HPO used in this technique is two transparent glass plates on which a liquid film between two pieces of transparent glasses is deposited and added a rotating object at the below HPO to modulate the phase of a PO. The measuring sensitivity can be improved by changing the transmittance of the absorptive HPO. Meanwhile, because the phase retardation of HPO can be continuously adjustable by modulate the rotating object, it makes the sensitivity of measurement at different wavelengths of laser optimal. Results show that the measuring sensitivity is improved 2-4 times compare with the conventional 4f imaging technique. Furthermore, the modified technique can be used to measure the spectrum of nonlinear refraction coefficients of materials at the continuous wavelength. This method further expands the 4f phase coherent imaging measurement technology, not only solves the deficiencies of the conventional phase object, but also improves the accuracy of the measurement. Experiment and theoretical analysis results are presented to validate our technique.

Linear‐Polarization‐Preserving Metasurfaces Based on Identically Spin‐Locked Geometric Phase

AbstractMetasurfaces have provided unprecedented degrees of freedom in controlling electromagnetic waves. By introducing geometric phase into metasurface, remarkable progresses have been made in manipulation circular polarized(CP) waves. However, for linearly polarized (LP) waves, polarization purity has to be sacrificed for wideband phase responses. Thus, it is desirable that wideband metasurfaces be explored for LP waves without polarization conversion. Herein, they propose a strategy of achieving wideband linear‐polarization‐preserving (LPP) metasurfaces based on identically‐spin‐locked (ISL) geometric phases. Different from the rotation‐induced oppositely‐spin‐locked (OSL) geometric phase (φL = −φR), the ISL geometric phase is the same for left‐ and right‐handed circularly polarization (LCP&amp;RCP) states (φL = φR). Since LP waves can be decomposed into LCP and RCP waves, the same phase can also be imparted to LP waves, without changing the polarization. Therefore, wideband LPP metasurfaces can be designed. As the proof‐of‐concept, the quadru‐arc structure (QAS) is proposed to construct the LPP metasurfaces. Two prototypes, one for vortex beam generation and the other for deflection‐absorption integration, are implemented. Both the simulated and measured results verify the LPP in wideband. This work opens a wideband gate towards wideband manipulation on LP waves and can be readily extended to higher frequency bands such as terahertz, infrared and optical regimes.

A Balanced Substrate Integrated Waveguide Phase Shifter with Wideband Common-Mode Suppression

In this paper, a slotted substrate integrated waveguide (SIW) is used to create a balanced phase shifter with wideband common-mode (CM) suppression. Differential-mode (DM) impedance matching and CM suppression are achieved by utilizing the fact that TE20 mode and TE10 (TE30) mode can only transmit DM signals and CM signals, respectively, and by increasing the bandwidth for CM suppression via slots. Furthermore, a wideband phase shift with low phase deviation can be obtained due to the phase slop counteract between the slot and the delay line. Compared with the state-of-the-art, the proposed one has the advantages of wideband CM suppression, wide phase shift range, and a simple and easy-to-make structure. Five prototypes covering the frequency of 3.5 GHz are designed with the relative operating bandwidth for 45° ± 2° (90° ± 4.5°, 135° ± 6°, and 180° ± 8°) phase shifter of 20% (20%, 20%, and 20%), with the minimum insertion loss of 0.41 dB (0.5 dB, 0.58 dB, and 0.59 dB), with the minimum return loss greater than 15 dB, and with the relative bandwidth for 15-dB CM suppression of 59% (59%, 58%, and 57%).

The Design of a Novel 2-42 GHz MEMS True-Time Delay Network for Wideband Phased Array Systems.

This article presents the design method of a compact MEMS switched-line true-time delay line (TTDL) network over a wide frequency range extending from 2 to 42 GHz using TTDL units. The TTDL units, namely the cascading radio frequency micro-electromechanical system (RF MEMS) switches and GCPW, were employed in the proposed TTDL network to improve the delay-bandwidth product (DBW) while maintaining its compact size and low delay variation (DV). For comparison, a theoretical analysis of the RF MEMS switch was performed while observing the switch performance with various top electrodes. The MEMS TTDL network has a compact size of 5 mm × 5 mm, with a maximum delay of 200 ps and a minimum of 30 ps. The maximum insertion loss of 9 states is 10 dB, and the in/out return loss is better than 20 dB across 2-42 GHz. The group delay variations are within ±2.5% for all the delay states over the operating frequency range. To the best of our knowledge, the proposed TTDL network obtains the most control bits among the TTDL networks offered to date.

Balanced Microwave Transmission Lines, Circuits, and Sensors

This paper provides an overview of balanced (or differential-mode) structures operating at microwaves, including common-mode suppression filters, balanced filters and circuits with intrinsic common-mode suppression, and differential-mode sensors. The increasing interest for balanced structures within the framework of communication circuits and sensors, related to their major robustness against electromagnetic interference (EMI), noise, and environmental factors, is duly justified. Then the paper reports various approaches for the implementation of common-mode suppression filters, balanced filters and circuits (including narrowband and wideband filters, multi-band filters, power dividers, couplers and phase shifters), and differential-mode sensors (mainly devoted to the measurement of permittivity and related variables). Rather than providing a detailed analysis of the different considered implementations/approaches, the main goal of this review paper is to discuss, and compare in some cases, the main proposed strategies (pointed out in the up-to-date state-of-the-art) for optimizing the performance of the various differential-mode devices under study.