With the rapid advancement of 5G mobile communication, the mm-wave band has become a focus of technological innovation for mobile terminal antennas. Our group is dedicated to overcoming the technical problems in the design of mm-wave mobile terminal antennas, particularly in terms of small ground clearance, wide bandwidth, single layer and integrated package. Through systemic research and exploration on the implementation of end-fire dual polarization, a series of high-performance mm-wave terminal antenna solutions have been developed. These works are categorized into two types, low-profile dual-polarized end-fire antennas and high-gain dual-polarized end-fire antennas.
The omnidirectional scanning periodic leaky wave antenna (PLWA) for reflected sidelobe suppression is presented. The proposed structure is symmetrically fed by two microstrip lines on the same side of a long rectangular patch. The proposed periodic antenna is composed of six uniform unit cells, and loaded with two shorting pins per period. The improved design can be used for reflected sidelobe suppression. The reflected sidelobe gain at 8.5 and 9 GHz are reduced by 18.9 and 18 dBi respectively compared to the antenna fed diagonally. The proposed antenna performs well when scanning from backward to forward, even when the scanning beam passes through the broadside. The simulated results show that the main beam scans continuously from 318˚ to 68˚ in the operating frequency band of 4.8–9.4 GHz.
This work presents a novel aluminum honeycomb structure with frequency-selective properties. The proposed frequency selective surface (FSS) is formed by loading metal surfaces with a Y-slot on the top and bottom of an aluminum honeycomb cavity. The proposed FSS structure with a thickness of 0.077λ 0 finally exhibits a bandpass response around 11.53 GHz with insertion loss less than 0.5 dB and good polarization stability.
This paper presents a novel approach to designing bandpass filters using a triple-mode dielectric waveguide resonator (DWR). The filter is composed of two triple-mode dielectric waveguide resonators. Each triple-mode resonator consists of a rectangular dielectric waveguide resonator with a square ring removed, where two half-wavelength microstrip resonators are plated. The fundamental TM 110 mode of the rectangular DWR and the TEM modes of the two microstrip resonators contribute to the triple-mode DWR. By utilizing triple-mode DWR, the number of resonators can be reduced, and a sixth-order filter can be designed with only two triple-mode DWRs. To activate the TM 110 mode along with one of the two TEM modes, a probe is introduced into the dielectric waveguide resonator and linked to the microstrip resonators. The source and the three modes of the triple-mode DWR forms a CQ coupling topology, generating a pair of transmission zeros outside the passband. The two triple-mode dielectric waveguide resonators are coupled magnetically, resulting in a sixth-order filter response and four transmission zeros outside the passband.
Strengths of terahertz synthetic aperture radar (THz-SAR) in high-resolution radar imaging and fine-grained target recognition have been widely proven. However, rotating targets existing in the scene will cause the defocus or ghost of the final result, which is not conducive to the subsequent image interpretation. To eliminate this adverse effect, it is necessary to accurately estimate rotation parameters. Taking special spectral characteristics of rotating targets into consideration, this paper extracts the signal of interest (SoI) from adopts the coarse focused result. Then, the inverse Radon transform of the time-frequency (TF) is applied to estimate the amplitude and the initial phase coarsely. Finally, both parameters can be searched and determined accurately according to the upper and lower envelop of TF distribution. Simulation results validate the feasibility and accuracy of the proposed method.
A subspace-based inverse source method is proposed for metasurface synthesis in this paper. More specifically, for the scenario that we hope the scattered fields of the metasurface are distributed in an arbitrary specified fields coverage region (FCR), the matrix G which establishes the mapping relationship between the equivalent sources and the fields in FCR is applied the truncated singular value decomposition operation so that the current sources can be divided into radiative and non-radiative currents. With the constraints of realizability, the scattered fields can be concentrated in the FCR by decreasing the proportion of non-radiative currents. A synthesis case is presented to demonstrate the details and validate the proposed method.
In this work, a novel low-profile wideband dualpolarized metasurface (MS) antenna with high isolation is proposed for C-band applications. To achieve dual polarizations, the MS is not only used as a radiator but also as a ground plane. In detail, for vertical polarization (VP), the MS is a radiator fed by a slot-coupled microstrip line, and for horizontal polarization (HP), the MS is a ground plane of a differential-coaxial patch radiator. The overall size of the proposed antenna is 1.1λ 0 ×1.1λ 0 ×0.079λ 0 (λ 0 is the free-space wavelength at 5.5 GHz). The simulated results show that the -10dB impedance bandwidths of the HP and VP are 28.4% (4.84~6.44GHz) and 38.7% (4.83~7.15GHz), respectively. Besides, the isolation between the two ports is higher than 51dB, and the maximum realized gain is 9.6dBi and 9.1dBi.
This paper presents a D-band 5-bit bi-directional active vector synthesis phase shifter in the 65nm CMOS technology for phased arrays. The possibility of implementing bi-directional active phase shifter at D-band frequency is verified. The bi-directional variable gain amplifier (Bi-VGA) as the core of the circuit utilizes the Gilbert cell. And the neutralized bi-directional technique is employed to improve the stability and gain of the circuit. The RMS phase error of the post-simulation can reach 0.88° and 0.98°, the RMS gain error can reach 0.83 dB and 0.9 dB respectively for forward and reverse mode from 135 to 145 GHz. The area of the chip is 0.32 mm 2 including pads. And the power consumption of the chip is less than 52.44 mW at 1 V supply voltage.
A wideband dual-polarized monopole antenna with a compact configuration is presented in this work which is the potential for the application of broadband wireless communication. The proposed design is based on the concept of the asymmetric CPW-fed half-cut monopole antenna. The designed antenna has a 10 dB return loss bandwidth of 104.4%, a gain of >2.5 dBi, and a good port isolation of >20 dB from 4.4 GHz to 10.4 GHz in a compact size of 0.7 λ × 0.7 λ × 0.023 λ ( λ is the wavelength at 7 GHz).
One broadband and high efficiency Class F power amplifier (PA) with a feedback circuit structure is proposed. Positive feedback is used to peak the gain and efficiency of the PA at high band. As a result, the PA is designed to have flat gain and efficiency performance over a wide bandwidth. Simulation results show that the PA has a power added efficiency (PAE) of 68.1%-72.6% and a gain of 10.6-11.4 dB in the frequency range of 1.6-2.6 GHz.
This paper proposes a dual helix antenna by using the novel substrate-integrated coaxial line (SICL) for millimeter-wave (MMW) applications. The helical part of the antenna is realized with $a\!\!\!\!{=}$ printed metallic strips designed with a certain scaling ratio for axial ratio bandwidth enhancement. The feed utilizes a SICL inverted phase power divider to achieve differential feed. The -10 dB bandwidth of the proposed antenna is from 31GHz to 45.7GHz (38.3%@38GHz), and the axial ratio bandwidth is from 35.4GHz to 41.4GHz (15.6%@38GHz) with a maximum gain of 9.11dBic.
Time-varying errors bring adverse effects to the mmwave microfluidic measurement system. In this paper, a method based on LSTM model is introduced to predict the drift errors, hence the consistency can be improved and the cost of time can be reduced, especially in mm-wave band. The paper started with analyzing of drift errors source then used LSTM model to build prediction model for drift errors. Experimental result showed that this method can predict drift errors effectively and improve the reliability of long-term measurement at mm-wave frequencies.
This paper presents a polarization reconfigurable antenna based on liquid crystal (LC) operating at around 14 GHz in the Ku-band. The antenna consists of two orthogonally-positioned defected ground structure (DGS) phase shifters loaded with LC together with a square radiating patch. By adjusting the permittivity of the loaded LC, the two DGS phase shifters can induce phase delays of 0°, +90° and -90° to the orthogonal radiating modes. This allows for the reconfiguration of the polarization states of the radiated far field from linear to right/left-handed circularly polarized state, correspondingly. The proposed antenna is fabricated using process compatible with the liquid crystal display (LCD) technology, ensuring that the antenna can be integrated into the existing manufacturing process. The simulated and measured results of the antenna indicate good polarization reconfiguration performances at Ku-band and can be further extended to higher frequencies in the millimeter wave regime.
A millimeter-wave wideband filtering patch with circular polarization (CP) for Ka-band satellite communication is presented in this paper. The proposed antenna is mainly composed of a pair of H-shaped feeding lines, a square patch, and a feeding network. The orthogonal H-shaped feeding lines are used to feed the patch by coupling. In addition, the feeding lines and the square slot etched on the patch work together to achieve a sharp roll-off rate at the lower-band edge. The feeding network consists of a Wilkinson power divider and a 90°-phase shifter to realize the right-hand CP (RHCP) and large bandwidth. As a result, the proposed antenna has wide bandwidth, stable realized gain and good out-of-band suppression. The simulated results show that the operating band with CP is 28.5-36 GHz, and the out-of-band suppression level reaches 21.7 dB.
A wideband feed network with microwave multilayer PCB technology in Ka band is put forward in this paper. Several transition models are also simulated and optimized based on theoretical calculation. The simulated results show that the feed network has properties of wide band, low insertion loss and low cost. It has potential for miniaturization microwave modules and phased control system.
This paper proposes a stubline coupling microstrip bandpass filter based on uniform impedance resonators. Additional coupling components are employed in the circuit to strengthen the coupling. In this way, the filters, which resonators all have the same orientation, can apply to frequency bands higher than VHF and UHF bands. A 5th-order filter prototype with a targeted central frequency of 7.17 GHz, a center loss of 0.88 dB, and a bandpass VSWR of 1.32 is proposed, simulated, and manufactured. A good agreement is demonstrated between the results of measurement and simulation.
Severe icing of transmission lines can cause adverse events such as power outages and tower collapses, which will damage social production and residents’ lives. The existing ice monitoring methods have some problems, such as non-standard monitoring and poor accuracy. In this study, we present a comprehensive artificial neural network (ANNs) model based on micrometeorological parameters and historical icing data to predict hard rime and glaze ice. The experiment verified 9 icing cycles in different years and different geographical locations. Results show that this method can effectively predict various types of icing with correlation coefficient >0.99 and mean square error < 4%.
In this article, a circularly polarized (CP) antenna with wideband performance and its 2×2 CP antenna array is presented for Millimeter-Wave Ka-band satellite communication. The proposed CP antenna element combines a stacked patch and a radiation slot, which are fed by an L-shaped feeding line, and the CP radiation can be generated in a wide mmW band. The CP antenna element operates from 25.5 GHz to 31.2 GHz (20.1%, S 11 < -10 dB) with an axial-ratio (AR) bandwidth (AR < 3dB) of 25.7-31.2 GHz. The CP antenna element has a stable broadside left-hand CP (LHCP) radiation pattern. Its 2×2 CP antenna array also has great LHCP radiation performance in the frequency band of 25-32 GHz. The average realized gain of the 2×2 CP array reaches 13 dBi.
In order to study the electromagnetic scattering characteristics of a composite scene of sea surface, ship and wake, this paper combines the methods of geometrical optics and physical optics (GO-PO), Kirchhoff approximation (KA) and facet scattering field model of sea surface. Firstly, the geometric model of the composite scene of sea surface and Kelvin wake is established by using Elfouhaily omnidirectional spectrum and classical ship wave generation theory. Secondly, the generated geometric model of the wake and sea surface is combined with the ship to generate a total scene model of sea surface, ship and wake. Finally, the scattering echoes of sea surface and wake are calculated by KA and facet scattering field model, in addition, the scattering echoes of ship and the coupling contribution between ship and sea surface are calculated by GO-PO. On this basis, the electromagnetic characteristics of the composite scene of sea surface, ship and wake under different conditions are discussed.
The problem of distributed collaborative guidance under the time delay caused by multiple missiles is investigated in this paper, and a distributed collaborative guidance law is proposed. Using graph theory, we analyzed the local communication topology among missiles and established a leader–follower collaborative communication model and closed–loop guidance system. Furthermore, by introducing a neutral operator in the guidance law and based on the Lyapunov theory, we investigated the asymptotic stability of the cooperative guidance model with constant time delay. We demonstrated that the guidance error converges to a bounded value. Finally, this guidance method’s effectiveness was validated through numerical simulations.
