To systematically evaluate the accuracy of GPS LNAV and CNAV broadcast ephemerides and verify their performance in real-time applications, this study conducted a year-long accuracy assessment for 2024 based on GNSS broadcast and precise ephemerides, complemented by validation through real-time orbit determination (RTOD) experiments using LEO satellites. Broadcast and precise ephemerides from 2024 were used to perform statistical analyses of ephemeris accuracy across different satellite blocks and navigation message types. In addition, reduced-dynamic RTOD experiments were carried out using onboard GPS observations from the GRACE-FO C satellite to assess the impact of different broadcast ephemerides on orbit accuracy. The results show that the accuracy of broadcast ephemerides varies significantly among satellite blocks, with BLOCK IIIA performing the best and BLOCK IIF performing the worst. After the clock source switch on G08 and G10 in 2024, the constellation-averaged SISRE for LNAV and CNAV broadcast ephemerides reached 25.5 cm and 23.8 cm, respectively, representing a substantial improvement compared to the LNAV SISRE of 37.0 cm in 2021. The LEO RTOD experiments further demonstrated that, compared to LNAV, CNAV provides improved accuracy in the along-track, cross-track, radial, and 3D directions, with a maximum reduction in 3D orbit error of 0.8 cm and an average improvement of about 3.2%, thereby confirming the advantage of CNAV in real-time applications. Overall, both the ephemeris accuracy statistics and LEO RTOD results consistently indicate that CNAV broadcast ephemerides outperform LNAV. With the gradual retirement of BLOCK IIR satellites and the continued deployment of BLOCK IIIA satellites, navigation, positioning, and timing services based on CNAV broadcast ephemerides are expected to achieve even higher accuracy, further enhancing their value for real-time positioning and scientific applications.

To address the issue of the baffle of antenna cover baffle obstructing signal transmission and receiving of vehicle ground station under low-elevation condition. Firstly, the solution of the foldable mechanism was identified and the bidirectional spring coaxial parallel system which defined the key technology was studied. Secondly, start with the movement process of the folding mechanism, the mathematical model of total system was established, the influencing factors of spring damping deformation and their analytical values were obtained. Then, the dynamic analysis of the spring coaxial parallel system was carried out, and the dynamic parameters of the system were obtained. The obtained three groups parameters were combined with the virtual prototype for dynamic simulation, and through the analysis of the torsional moment curves under the separate action of the inter and outer springs and their joint action. The results showed that the proposed bidirectional spring coaxial parallel system acted alone compared with the inter and outer springs. The value of dynamic peak not only attenuated significantly(approximately 75 %~90 %)but also the dynamic peak frequency was significantly reduced, which verified that the structure with inter and outer springs connected in coaxial parallel had more stable dynamic characteristics, and which provided the favorable reference for other similar engineering projects.

To meet the demand for highly efficient folding and high gain antenna used in CubeSats, a deployable reflector antenna that can be tightly coiled was presented using flexible composite materials. The antenna was mainly composed of flexible reflector, cylindrical shell boom, sub-reflector and feed. The cylindrical shell booms play the role to deploy and maintaining the flexible reflector in the needed shape. One end of each cylindrical shell boom was connected to the periphery of the reflector, while the other one was fixed to the center of the antenna. A simple method was developed to predict the coiling load using elastic Euler beam theory. A 0.5 m prototype antenna was constructed and tested for coiling deployment and RF performance. The diameter and height of the prototype in coiled state were nearly 140 mm and 180 mm separately, and the predicted constraint load was 24% higher than the test value.

With the rapid development of satellite communication technology, the volume of data transmitted between satellites and ground stations continues to increase, driving higher demands for signal transmission rates and quality. In traditional modulators, due to limitations such as DAC(Digital-to-Analog Converter)sampling rates and shaping filter technologies, low-order modulation is often adopted, resulting in lower signal transmission rates that cannot meet the requirements of future high-speed transmission. Therefore, a 16-channel parallel shaping filter technology with a continuously variable transmission rate is proposed in this paper. This technology employs 64APSK(Amplitude Phase Shift Keying)modulation to achieve high-speed data transmission. Experimental results show that, based on the existing hardware platform, data transmission at a rate of 7.2 Gbps is achieved with a 4.8 GHz DAC sampling rate, and the EVM (Error Vector Magnitude)is as low as 2.029 9%. Compared to the original high-speed modulator architecture, this technology offers advantages such as high transmission rates, good signal quality, and low resource consumption, making it a valuable reference for the design of future systems for data transmission exceeding 10 Gbps.

With the increasing application demands for radar jammers, traditional array designs and direction-finding algorithms exhibit critical limitations: excessive information redundancy in uniform arrays, restricted estimation accuracy due to limited physical aperture, and significant performance degradation when processing coherent signals. To address these issues, this paper proposes a coherent signal Direction of Arrival (DOA) estimation method based on spatial smoothing preprocessing and the MUSIC algorithm, integrated with a two-dimensional composite uniform arrays. The method aims to overcome traditional array design constraints and mitigate DOA performance deterioration caused by coherent signals. Specifically, the spatial smoothing technique leverages the translational invariance property of uniform arrays to effectively solve the rank deficiency in covariance matrices induced by coherent signals. The two-dimensional composite uniform array adopts a sparse array configuration to expand the effective aperture under the same number of array elements, thereby enhancing DOA resolution. Experimental validation combines two-dimensional spatial smoothing with the MUSIC algorithm for DOA estimation of coherent signals on the composite array. Results demonstrate that the spatial smoothing method successfully suppresses coherent signal interference, while the composite array achieves superior DOA estimation performance compared to traditional uniform arrays with identical element counts, validating the effectiveness of the proposed methodology.

In the guidance and control of the first-stage recovery of rocket, the carrier pose measurement is very important. Inertial navigation, satellite navigation, LiDAR are usually used to measure the pose in engineering, while there is no precedent for visual measurement. Visual measurement has the advantages of no cumulative error and high update rate, and has the potential to be applied to rocket recovery. In this paper, the dynamics model of rocket recovery is analyzed and trajectory simulation is carried out, and the Falcon9 rocket is taken as the simulation object and the optimal trajectory is obtained by a convex optimization method. Four cameras were installed in the first stage of the rocket, and the visual pose measurement was realized through the multi-vision sensor measurement model, image target recognition and feature picking. The calculation results show that the visual measurement technology proposed in this paper has a high position accuracy and has the prospect of engineering application.

Integrated circuit nanotechnology is gradually approaching the physical limit. Therefore, relying on heterogeneous integration technology to continue and expand Moore Law is becoming increasingly important. The vertical interconnection of signals from various integrated chips is achieved through technologies such as through silicon via (TSV) or through glass via (TGV), while high-density interconnection in the horizontal direction can be achieved through rewiring layer (RDL) technology. The article summarizes the comparison between TGV technology and adapter boards, elaborates on the current application status in the field of passive systems and RF 3D integration, analyzes the TGV process capability and the current technical progress of domestic and foreign manufacturers, and explores the existing technical difficulties and future development trends of the TGV.

This paper delves into the applications and the technological advancements of silicon-based analog beam- forming chips in high-frequency, high-bandwidth communication and phased-array radar systems. The context of 5G and the prospective 6G networks, which impose increasingly stringent demands on data transmission rates, anti-interference capabilities, and signal quality, So beam-forming technology has emerged as a pivotal factor in enhancing the performance of both communication and radar systems. Initially, this paper expounds on the fundamental principles of silicon-based analog beam-forming chips, highlighting their distinctive advantages in terms of low power consumption, high integration, and precise beam control. Moreover, it explores in depth exploration of the strategies for optimizing the silicon-based material processing techniques to improve frequency response and bandwidth handling capabilities. Subsequently, the paper elaborates on the key technologies embodied in silicon-based analog beamforming chips, including attenuators and phase shifters. Conclusively, the paper offers a forward-looking perspective on the future development trends of silicon-based analog beam-forming chips. Particular emphasis is placed on discussing the potential of technologies such as adaptive beam-forming, low-latency control, multi-functional integration, and the application of novel materials. The novelty of this research lies in the introduction of beam isolation technology, and the proposition of a viable approach to enhance frequency response and bandwidth processing capabilities through the optimization of silicon-based processes. This contributes to providing essential technical support for future wireless communication and radar systems.

This paper presents the design of a 24~30 GHz frequency tripler based on a 65 nm CMOS process, aiming at enhancing the performance of local oscillator (LO) chains in millimeter-wave communication systems. By leveraging the nonlinear characteristics of MOS transistors, the design optimizes the bias voltage and matches network to enhance the third harmonic while suppressing the fundamental and higher-order harmonics. The proposed frequency tripler employs a two-stage architecture: the first stage utilizes a differential common-source common-gate (CSCG) structure, efficiently extracts and amplifies the third harmonic, while the second stage, a power amplifier, further optimizes the bandwidth and output power through load-pull analysis. Post-layout simulation results demonstrate a 3 dB bandwidth of 24~30 GHz, achieving a relative bandwidth of 22%. At 27 GHz, the tripler delivers a saturated output power of 7.4 dBm, with a maximum in-band conversion gain of 4.2 dB. The suppression levels for the fundamental and fifth harmonics are 29 dBc and 28 dBc, respectively, maintaining good performance over a wide input power range. This design provides an efficient and compact solution for K/Ka-band LO chains in millimeter-wave communication systems.

With the continuous advancement of radar technology, broadband phased array radar has been widely applied in fields such as remote sensing, environmental monitoring, and 5G base station communications due to its high resolution, multi-tasking capability, and adaptability to complex electromagnetic environments. However, traditional phased array radars rely on phase shifters to control beam direction, which can lead to beam squint in broadband applications, ultimately reducing detection accuracy. To address this issue, this paper presents a high-area-efficiency true time delay (TTD) circuit based on an artificial transmission line(ATL) delay unit. Fabricated using a 0.13 μm SiGe BiCMOS process, the TTD circuit operates across the frequency range from S to Ku bands and features a 6-bit digital delay control, achieving a minimum delay resolution of 6 ps and a maximum delay of 378 ps. The circuit incorporates delay reference paths with T-type and π-type attenuator structures, ensuring optimal gain matching with the delay units. Additionally, by integrating passive switches and distributed cascaded gain equalizers, the design enhances delay accuracy and gain flatness. Through HFSS optimization of spacing of inductors in the ATL delay unit, the layout efficiently reduces inductor area consumption. As a result, the fabricated chip measures only 3 mm × 0.9 mm, offering a delay density of 141.6 ps per unit area. Measurement results show that the root mean square (RMS) delay error across all states is less than 5.9 ps, while the circuit exhibits a gain performance of -5.5 to -1 dB within its operating frequency range under a 2.5V power supply. This work makes a significant contribution to the development of high-performance phased array radar systems.