4-bit Phase Research Articles

1-Bit Reconfigurable Transmitarray Antenna with Out-of-Band RCS Reduction

Stealth reconfigurable transmitarray antennas (RTAs) are essential components in wireless communication and radar detection systems. Therefore, in this study, we propose a 1-bit RTA with out-of-band radar cross-section (RCS) reduction. The antenna consists of an absorptive frequency selective transmission (AFST) layer and RTA layer separated by air. Specifically, the AFST layer achieves out-of-band RCS reduction and in-band transmission utilizing the first three resonant modes of a bent metallic strip with a centrally loaded resistor. Meanwhile, the RTA layer adopts a receiver–transmitter structure with an active receiving dipole and a passive orthogonal transmitting dipole. 1-bit phase shift is achieved by alternating two pin diodes integrated on the active dipole to reverse its current direction. To evaluate the proposed design, a 16 × 16-element prototype was designed, fabricated, and measured. For scattering, the bandwidth of 10 dB RCS reduction was about 52.5% and 43.8%, respectively. For radiation, the measured gain was 20.1 dBi at 7.5 GHz, corresponding to an aperture efficiency of 12.7%. The gain loss of beam scans to ±60° was about 5 dB in both two principal planes.

A 1-bit passive reconfigurable metasurface for wide-angle scanning and broad-beam reflection

ABSTRACT A reconfigurable reflective metasurface design is proposed in this letter, allowing for beam scanning capabilities. This paper integrates a tunable capacitor into the metasurface unit. This paper integrates a tunable capacitor into the metasurface unit. The resonant characteristics of the metasurface unit are controlled by the tunable capacitor, which can be adjusted by changing the rotation angle of the metal plate on the tunable capacitor. By rotating the metal plate of the capacitor, it achieves state 1 at maximum capacitance and state 0 at minimum capacitance, resulting in a phase difference of 180° ± 20° between the states, thereby enabling 1-bit phase control. Leveraging the principle of phase compensation, the phase distribution of the array is designed to exhibit directional radiation characteristics. A reflective metasurface composed of a 20 × 20-element array is designed and simulated with these characteristics. The simulation results indicate that the scanning angle of the array-reflected beam can reach ± 50°, with a peak gain exceeding 14.6 dBi, an average gain of 13.8 dBi, and a gain loss of 1.5 dB. The beam’s 3 dB beamwidth exceeds 15°, enabling broader coverage. Joint simulations in typical indoor scenarios confirm the improved signal strength, highlighting the array’s versatility. This design allows the reflective array to function as a passive reflector relay, effectively improving signal coverage in indoor NLOS.

Programmable metasurface based phase-modulating reflector for 2.4 GHz wireless communications

Abstract This paper presents an innovative programmable metasurface structure that achieves precise phase control within the 2 to 2.7 GHz frequency range by adjusting the state of varactor diodes embedded in the unit cells. The design employs a single diode, which simplifies the structure, reduces manufacturing costs, and minimizes reflection loss. At 2.4 GHz, the metasurface achieves 1-bit phase responses of 0° and 180°, with a reflection amplitude exceeding 0.72, demonstrating excellent reflective performance. Moreover, as the 2.4 GHz frequency is closely related to wireless communication bands, this programmable metasurface shows significant potential in the field of wireless communication encryption. By integrating dual varactor diodes, the design enables 2-bit phase control with reflection phase angles of 0°, 90°, 180°, and 270°. To validate the design, a 1-bit metasurface structure was fabricated and tested, with experimental results showing a high degree of consistency with simulations, highlighting the potential of this structure in enhancing wireless communication security.

Anisotropic programmable metasurfaces with individually controllable 2-bit elements

Programmable metasurfaces capable of manipulating electromagnetic (EM) waves in real time provide new opportunities for various exciting applications. However, most previous programmable metasurfaces only work in a single polarization mode and their elements are controlled in a whole or one-dimensional way, which limits functionality and adaptability to complex environments. Here, an anisotropic programmable metasurface with individually controllable elements is proposed to realize real-time and independent dual-polarized EM control in the two-dimension direction. The anisotropic metasurface element is designed using the ingenious cross-over resonant structure integrated with two sets of varactors to achieve 2-bit phase modulation in the respective polarization direction. As a demonstration, an anisotropic programmable metasurface prototype with 21×20 such elements is simulated, fabricated, and measured. Real-time beam scanning and vortex wave generation are verified respectively under two different polarized wave incidences, which indicates that the realized anisotropic programmable metasurface can achieve totally distinct functionalities for two orthogonal polarizations. Our work could push programmable metasurfaces one step closer towards more advanced information devices and complicated applications in communication and imaging.

A quad-polarization reconfigurable transmitarray antenna with beam-scanning and reconfigurable polarization capabilities

Abstract In this paper, a novel quad-polarized electronically reconfigurable transmitarray antenna(QRTA) is proposed, which can actively switch among four linear-polarization modes and steer beam-scanning in these polarization modes. The QRTA element follows a receiving-transmitting structure. Its receiver or transmitter is composed of four rotationally symmetric patches and a coupling patch. Four rotationally symmetric patches generate x- and y-polarization modes, while coupling patches on the top and bottom layers of the QRTA element are designed to synthesize x-, 45◦-, y-, and 135◦-polarization modes. The QRTA element utilizes a reverse symmetry current method to achieve a 180◦ phase difference in the radiated electromagnetic waves. By manipulating the state of the p-i-n diodes, the proposed QRTA element can achieve four LP functions and a 1-bit phase shift. Based on the proposed novel QRTA element, a 10 × 10 elements QRTA prototype is fabricated and measured. The measured results demonstrate that the proposed QRTA can electronically switch between four LP modes and achieve beam-scanning in those LP modes. The proposed QRTA shows several advantages, including low cost, multi-polarization capability, high gain, and beam-scanning, which means that it can enhance the polarization capabilities and intelligence of wireless communication systems.

Deep learning and genetic algorithm driven accelerated design for frequency-multiplexed complex-amplitude coding meta-hologram.

Frequency-multiplexed metasurfaces represent a significant innovation in breaking the functional limitations of traditional metasurfaces, showing immense potential in multi-channel communication. However, existing frequency-multiplexed metasurfaces primarily focus on pure phase and linear polarization modulation, neglecting the modulation for complex amplitude and circularly polarized waves. Additionally, crosstalk suppression between dual-frequency channels often requires meticulous tuning of the meta-atom structure. Therefore, manually designing a set of meta-atoms that satisfies both complex amplitude modulation and low crosstalk at dual frequencies is extremely challenging and time-consuming. Here, we utilize the method of deep learning and genetic algorithm to design a kind of meta-atom capable of bi-spectral 2-bit amplitude and arbitrary phase modulation, which greatly reduces the design difficulty and achieves excellent low-crosstalk performance. This method can be easily generalized to the design of other complex meta-atoms to improve the design efficiency. Furthermore, we propose a frequency-multiplexed complex-amplitude coding meta-hologram for modulating left-handed circularly polarized (LCP) waves. When illuminated with LCP light, it can reconstruct two distinct holographic images at two different frequencies in the near field with high quality. The independent modulation capability of the metasurface for multiple degrees of freedom of frequency, amplitude and phase gives it broad application prospects in multi-channel communication, data storage and perfect holography.

A novel differential chaos shift keying system based on joint time slot and code index of carrier phase modulation

This paper proposes a novel differential chaos shift keying (DCSK) system that utilizes carrier phase modulation in combination with time slot and code index modulation, referred to as CP-TCIM-DCSK system, to achieve high data rate transmission. In the proposed CP-TCIM-DCSK system, the carrier modulated by the carrier phase is used to transmit the information-bearing signal. In addition to physically transmitted information bits, extra information bits are conveyed through time slot and Walsh code modulation, as well as carrier phase modulation, making full use of the benefits of multidimensional modulation. To successfully estimate carrier phase bits and code index bits, an effective joint detection algorithm for carrier phase and code index tailored for the CP-TCIM-DCSK system is introduced. The theoretical Bit Error Rate (BER) expressions for the CP-TCIM-DCSK scheme are derived for both Additive White Gaussian Noise (AWGN) and multipath Rayleigh fading channels. Furthermore, a comparison of data rates, energy efficiency, and complexity between the CP-TCIM-DCSK system and the most advanced systems in the same category at present is conducted. The results validate the accuracy of theoretical analysis through simulation and demonstrate that the proposed scheme outperforms its competitive systems in terms of BER performance.

A wafer-level 3D integrated T/R microsystem with 0.5-wavelength self-matching connectors

Achieving high performance, multifunctionality, and a compact size simultaneously in a single T/R module presents a significant challenge. In this work, both the 'chiplet' technique and 3D integration technique are adopted to form a T/R microsystem using self-matching interconnectors. Such T/R microsystem consists of four GaAs chips and one CMOS chip. The designed microsystem with a small size is utilized for the application of tile-type mmWave active phased array. Its measured results demonstrate good performance in terms of high gain, large output power, 6-bit phase shift, and 6-bit attenuation, confirming the effectiveness of our adopted architecture and design method. As such, this work provides a valuable design guideline for the chiplet-based 3D integrated RF microsystem.

An 8~18 GHz 6-bit phase shifter with balance-compensated balun

An 8~18 GHz 6-bit phase shifter with balance-compensated balun

A broad-beam reflective metasurface enhancing signal coverage for indoor wireless communication

ABSTRACT A broad-beam planar reflective metasurface design for indoor signal coverage is presented in this letter. The proposed metasurface unit is designed as a multi-resonant structure using an additional branch on the double ring, which achieves a reflection phase shift covering 360° and a reflection magnitude remaining above 0.8 by varying the length of the square ring. To simplify the array configuration, the unit incorporates 2-bit phase quantization. In order to broaden the reflection beam of metasurface, the phase distribution of the array is determined by the aperture field superposition method. The angles of the different electromagnetic (EM) waves within the single aperture are adjusted to be moderately distinct. The co-simulation and measurement of the horn antenna and the reflective metasurface are carried out. The results show that the metasurface can generate a broad beam at 4.8 GHz with a 3 dB beamwidth of 21°, achieving a beam gain of 18dBi. The broad beam can maintain a 3 dB beamwidth greater than 19° in the 4.2–5.6 GHz band. The reflective metasurface can be used as a passive repeater to optimize signal quality and enhance wireless communication coverage in indoor non-line-of-sight (NLOS) paths.

A 27 ​GHz, simple 2-bit 1×8 phased array

This study demonstrates a simple 2-bit phased array operating at 27 ​GHz that supports one-dimensional beam scanning with left-handed circular polarization (LHCP). The antenna is constructed using a compact four-layer printed circuit board (PCB) structure, consisting of a 90° phase shifter layer with microstrip structures, a ground (GND) layer, a direct current (DC) control layer, and a circularly polarized annular radiation patch layer with 1-bit phase shifting. Based on the proposed unit structure, a 1×8 array with half-wavelength inter-element spacing was designed and validated. Experimental results show that the array achieves a peak gain of 10.23 dBi and is capable of beam scanning within ±50°.

Design of 2.5-3.3 GHz high-precision compact digital phase shifter

Abstract A 6-bit MMIC digital phase shifter, designed using a 0.5 μm GaAs pHEMT process, has been developed to enhance the search capability of phased array systems for targets. The chip structure of the phase shifter is well-designed, and the improved embedded topology of the 45° and 90° phase shifting units effectively reduces the overall insertion loss. To reduce the chip size, the phase shifting units with smaller layouts of 5.625°, 11.25°, and 22.5° are combined, greatly reducing the chip area. The results show that within the frequency range of 2.5-3.3 GHz, the input and output VSWR is less than 1.38, the insertion loss is less than 4.3 dB, the root mean square phase error of the phase shifting state is less than 1.43°, and the absolute value of the amplitude fluctuation for different states is less than 0.52 dB. The compact chip structure measures 2.45 mm×1.08 mm.

A Planar Time-Modulated Array With Integrated 2-bit Phase Modulators

A Planar Time-Modulated Array With Integrated 2-bit Phase Modulators

Complementary split resonant ring inspired wide-angle frequency-scanning patch array leaky-wave antenna with open-stopband suppression

In this paper, a wide-angle scanning and dual-linearly polarized leaky-wave antenna (LWA) is proposed based on symmetrical complementary split resonant ring (CSRR) feeding lines. The CSRR excites high-dispersed spoof surface plasmon polaritons (SSPPs) and is inspired to enlarge the scanning angle of the circular patch array antenna. The coupling between CSRR and circular patch determines the unit cell dispersion characteristics of LWA, and the coupling between CSRR and circular patch is controlled by designing their respective periods, p/b, to suppress the open-stopband and reduce the grating lobe, The value of p/b controls the frequency range of the open-stopband. Two parallel CSRR feeding lines are located on the bottom layer of the antenna and feed the array antenna of 11 circular patches above the feeding layer with both differential and common modes excitations. The two modes switch with 1-bit phase shifters on the two parallel feeding lines fed with a Wilkinson power splitter and electronically switch dual-linearly polarized radiations. The proposed scenario of the LWA prototype is validated through simulations and experiments. According to the measurements, horizontally polarized radiation achieves large beam scanning angle from −59.5° to +40° in the frequency range from 8 to 11 GHz with common mode excitation. And vertically polarized radiation scanning the main beam from −47° to +41° in the frequency range from 7.8 to 10.8 GHz with differential-mode excitation. The measured peak gains of the two polarizations are 14.4 dBi and 14.2 dBi, respectively, and the cross-polarization ratios are above 21 dB.

A novel 6.5-13.5GHz 6-bit digital phase shifter with ultra low RMS phase error in 0.25-µm GaAs p-HEMT technology

A novel 6.5-13.5GHz 6-bit digital phase shifter with ultra low RMS phase error in 0.25-µm GaAs p-HEMT technology

A Ka-Band Two-Channel Two-Beam Receiver Based on a Substrate-Integrated Suspended Line

To realize the miniaturization and high performance for the key transceiver components of a phased array antenna, we proposed a two-channel two-beam receiver based on a substrate-integrated suspended-line (SISL). Multi-layer composite substrate printing circuit is used in the SISL structure to replace the metal cavity and passive circuits. The active components are placed in the air cavity in the SISL structure. The substrates forming the cavity are soldered together to ensure the hermetic seal and high performance. The SISL circuits have the advantage of low loss, low cost, light weight, self-packaging, and high inter-channel isolation. The proposed Ka-band two-channel two-beam receiver shows a gain of >28 dB, a noise figure of <2.6 dB, with functions of 6-bit phase shifting and attenuation.

Gain and mode purity filtering dual polarized OAM beam generation using cavity waveguide-based 3D transmitarray

A 3D transmitarray (TA) is proposed to generate dual-polarized orbital angular momentum (OAM) beams with gain and mode purity filtering responses. The TA units are realized by square cavity filters with the same passband and different orders and inner widths, resulting in different coupling cavity numbers. The evanescent modes in the coupling cavities will greatly decrease the propagation constant, thus generating a large phase variation. The square structure of the cavity filter makes it able to support dual-polarized wave propagation with the same phase delay and insert loss. Based on these transmission characteristics, eight different TA units are designed to realize a 3-bit phase gradient within the passband of 25.4–26.7 GHz. It should be emphasized that the dispersed transmission phase and magnitude of the eight TA units in the stopbands will deteriorate the purity of the OAM beam. Therefore, the gain and mode purity filtering responses can be realized simultaneously. In order to verify the performance of the proposed OAM TA design, a TA prototype with the mode number l = −1 is fabricated by 3D printing technology. The TA can realize the maximum gain of 25.9 dB in the passband, and the rejection level is below −15.0 dB within the main beam direction. The purities of dual-polarized OAM beams are over 0.5 in the passband, and the cross-polarization is below −16.5 dB. The advantages of the OAM TA, including gain-filtering and mode purity-filtering responses, dual-polarization, and high efficiency make it a promising solution for millimeter-wave OAM sensing and communication applications.

Dual-polarized bidirectional beam-steering array with beam-scanning capability in full-space

This paper presents a dual-polarized bidirectional electronically reconfigurable beam-steering array (DBSA) for the first time, which integrates the beam-scanning capabilities of both dual-polarized reconfigurable transmitarray and dual-polarized reconfigurable reflectarray. First, a novel phase and direction reconfigurable dual-polarized element is proposed. Four PIN diodes are soldered onto the symmetric transmitting patches to tune the 1-bit transmission phase, while two PIN diodes are soldered onto the reflecting patches to tune the 1-bit reflection phase. By controlling the states of the PIN diodes, the DBSA element can achieve 1-bit reconfigurable phase in both transmission and reflection modes. Second, based on the proposed element, a 100-element DBSA prototype is fabricated and measured. At dual-polarization, the angles of the scanned beams can reach 45∘ and 222∘ in forward- and backward-spaces. Therefore, the proposed novel method opens a new avenue to designing a dual-polarized electronically reconfigurable spatially fed array antenna with full-space beam-scanning capabilities, and the proposed design is suitable for dual-polarized bidirectional wireless communication applications.

Complex-Amplitude Programmable Versatile Metasurface Platform Driven by Guided Wave.

Metasurfaces have shown unparalleled controllability of electromagnetic (EM) waves. However, most of the metasurfaces need external spatial feeding sources, which renders practical implementation quite challenging. Here, a low-profile programmable metasurface with 0.05λ0 thickness driven by guided waves is proposed to achieve dynamic control of both amplitude and phase simultaneously. The metasurface is fed by a guided wave traveling in a substrate-integrated waveguide, avoiding external spatial sources and complex power divider networks. By manipulating the state of the p-i-n diodes embedded in each meta-atom, the proposed metasurface enables 1-bit amplitude switching between radiating and nonradiating states, as well as a 1-bit phase switching between 0° and 180°. As a proof of concept, two advanced functionalities, namely, low sidelobe-level beam scanning and Airy beam generation, are experimentally demonstrated with a single platform operating in the far- and near-field respectively. Such complex-amplitude, programmable, and low-profile metasurfaces can overcome integration limitations of traditional metasurfaces, and open up new avenues for more accurate and advanced EM wave control within an unprecedented degree of freedom.

Dual-band dual-polarized sub-6 GHz phased array antenna with suppressed higher order modes

This manuscript proposes a dual-band dual-polarized 64-element phased array antenna (PAA) with suppressed higher order modes (HoMs). Each array element is a microstrip patch structure with complementary split ring resonator (CSRR) loading, allowing for simultaneous dual-band and dual-polarization performance at 3.45 GHz and 3.87 GHz. The proposed PAA exhibits impedance matching of ≤-20\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\le - 20$$\\end{document} dB at 3.45 GHz and 3.87 GHz while limiting the mutual coupling below -19\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$- 19$$\\end{document} dB between the adjacent elements at both the operating bands. The proposed design includes a plated through hole placed near the CSRR loading to suppress any higher-order modes (HOMs). Two antenna prototypes, without and with HOMs suppression techniques are fabricated and measured. In addition, we demonstrate the beam steering of the proposed PAA up to ±600\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pm 60^0$$\\end{document} using an off-the-shelf 6-bit phase shifter module. The proposed 64 -element array achieves a gain of 23 dBi, and shows a minimal steering loss of ≃3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\simeq 3$$\\end{document} dB over the steering angle.