The development of wireless communication technology has imposed strict requirements on antennas, including high-frequency operation, miniaturization, and strong directivity, to support higher data transmission rates in the future. Due to inherent amplitude and phase differences among channels in millimeter-wave chips and multi-antenna arrays, as well as additional amplitude and phase differences caused by factors such as temperature characteristics and aging during operation, beamforming accuracy can be significantly degraded. To mitigate the impact of inter-channel amplitude and phase differences on beam control, this paper proposes a near-field calibration algorithm based on plane wave spectrum expansion. The algorithm constructs a signal model between the antenna under test (AUT) and the probe using plane wave spectrum theory. Based on this model, a virtual signal for calibration measurement is generated and compared with the measured signal. A genetic algorithm is used to optimize the difference between the virtual and measured signals, and the initial excitations of the millimeter-wave array antenna are determined when the difference reaches its minimum. To validate the effectiveness of the proposed calibration algorithm, a four-element millimeter-wave linear array was calibrated. The probe scanning range was approximately one-third of the array aperture. The obtained amplitude calibration error range was ±0.43 dB, and the phase calibration error range was ±4.6°, achieving high-precision calibration.

In this paper, we propose a novel method of attitude determination for spinning vehicles based on standalone GNSS. A baseband algorithm is first developed to resolve the shadowing effect encountered by 4-antenna receivers mounted on spinning vehicles, enabling continuous and precise signal tracking. Then the particular geometry of the 4-antenna configuration is exploited to yield differential ENU-velocity vectors from co-located antennas. By taking the inner product, the vehicle's pose information is derived from the orthonormality of rotation matrices, and yields the roll rate in the body frame. Finally, we use the roll rate to devise linearly independent differential vector pairs and solve for the rotation matrix in the linear system relating ENU velocities and body-frame velocities. The attitude information, defined by Tait-Bryan angles, can thereby be resolved. The algorithm presented is implemented in a 4-antenna real-time GNSS receiver and experiments are carried out with a spinning cylindrical platform. The results are confirmed via evaluation of the PVT results and comparisons with the platform's true attitude.

Aerial-space image matching is one of the significant research directions of unmanned aerial vehicles. This paper systematically constructs a framework for matching heterogeneous aerial-space images and provides an in-depth analysis of its key components. Based on literature review, this paper categorizes the key technologies of the heterogeneous image matching framework into three major types: image quality assessment technology, image preprocessing technology, and image matching technology. It summarizes the latest advancements in each of these technologies, with a particular focus on analyzing the technical differences in their application to the UAV field. Based on this, cross-comparison experiments are conducted using datasets to analyze the specific effects of each method. Finally, the paper summarizes the challenges faced in matching heterogeneous aerial and space images and provides an outlook on future research directions and development trends.

During the execution of precision measurement and control tasks by ground - based equipment, in order to accurately track the angular error demodulation signal, phase and slope correction of the tracking receiver are required, and the process of obtaining the correction value is called phase calibration. Ensuring the precise phase difference calibration of the sum and difference receiving channels is a key step to meet the self - tracking requirements of the target for the angle measurement subsystem. The traditional phase calibration method for multimode feed tracking systems faces challenges such as low efficiency, susceptibility to calibration equipment failures, and the impact of field setup environments, which not only limits the smooth progress of measurement and control tasks but may also have an adverse effect on the accuracy of target tracking. This paper aims to study and analyze existing calibration methods, deeply mine the existing calibration data, and introduce the method of multiple fitting analysis of mathematical statistics to predict the phase shift value, thereby effectively enhance emergency measurement and control capability of the measurement and control equipment in practice, ensuring the continuity and accuracy of task execution.

With the ongoing advancements in equipment informatization and lightweight design, the development of navigation guidance and control (GNC) systems faces escalating complexity, while demands for system miniaturization and weight reduction grow increasingly urgent. System-in-Package (SiP), a high-density integrated packaging technology, addresses these challenges by encapsulating multiple functional chips into compact cavities, thereby achieving enhanced integration and system miniaturization. To meet the miniaturization requirements of GNC systems, this study presents a GNC information processing microsystem circuit designed using SiP technology. The circuit employs a DSP+FPGA architecture, integrates diverse interface and memory chips, and leverages mature ceramic substrate microsystem integration techniques. Comprehensive multi-physics simulations were conducted to validate the design. Experimental results demonstrate normal circuit functionality and full compliance with design specifications. Compared to the prototype verification board, the optimized circuit exhibits dimensions of 45 mm×45 mm×11 mm and a weight of approximately 60 g. Substituting traditional board-level systems with this circuit significantly improves product integration and fulfills critical miniaturization requirements for control systems.

By constructing an angle tracking loop model and performing simulations in the phased array TT&C (Telemetry, Tracking and Command) system, it is used to assist in designing the parameters for the α-β filtering estimation algorithm in the angle tracking loop and the closed-loop period and delay time of the entire loop. Firstly, the equipment composition of the phased array antenna angle tracking system is introduced, and a simulation model of the angle tracking loop is constructed. Then, when the parameters of the filtering estimation algorithm and the closed-loop period and delay time of the angle tracking loop change, the step signal is used to test the dynamic response performance of the angle tracking loop, and based on this, the design parameters of each link in the loop are determined. Subsequently, constant-velocity signals and sinusoidal signals are used to simulate the maneuvering characteristics of the flight target, and the lag error of the angle tracking loop is simulated to verify whether the design parameters meet the usage requirements of the system. Finally, the sinusoidal signal is used to simulate the disturbance characteristics of the antenna carrier platform. The anti-disturbance performance of the angle tracking loop is verified through loop lag error simulation, and by simply improving the filtering estimation algorithm, the anti-disturbance performance of the loop is improved. Experimental results demonstrate that modeling and simulation of the angle tracking loop enable rapid parameter and algorithm design for all components in the loop, significantly reducing trial-and-error costs.

Aiming at the absolute and relative location service needs of low-altitude flight drones in complex electromagnetic environments, a three-dimensional distributed drone cooperative localization method based on high-precision ranging information is proposed. All nodes in the cluster are equipped with navigation positioning sensors with the same accuracy, and use the inertial error as a state variable, the height value of the altimeter as a height measurement and 0.1 Hz visual matching information as position and speed measurements to correct the absolute positioning error of the nodes. Use the ranging values of the nodes as cooperative measurements to correct the relative positioning error, and use the extended Kalman filter to fuse the measuring range and inertial/altimeter/vision system output. Construct the flight test scene of the 6-node drone group to complete the simulation verification of low-altitude flight scenes. Verified, through the cooperative positioning algorithm, the absolute position accuracy is improved by 61%, and the relative positioning accuracy increases by 93%, which proves the effectiveness of the cooperative localization method.

The annual large-scale outbreak of Enteromorpha prolifera in the Yellow Sea brings serious harm to the marine environment. Monitoring it by remote sensing technology is the most effective early warning method for dealing with the Enteromorpha prolifera disaster. In remote sensing images, Enteromorpha prolifera is mostly discrete small targets with irregular shapes, and traditional interpretation algorithms suffer from low interpretation accuracy and efficiency. To address this issue, this paper proposes a high-precision Enteromorpha prolifera detection method based on the PSPNet network, which embeds the DAM attention mechanism module to enhance the network's attention to Enteromorpha prolifera regions in remote sensing images. Then, the DBSCAN clustering algorithm is used to draw the contours of Enteromorpha prolifera regions and provide Enteromorpha prolifera interpretation results. Experimental results on MODIS remote sensing images of Enteromorpha prolifera show that the PSPNet+DAM model can achieve high-precision and high-efficiency Enteromorpha prolifera detection, and the DBSCAN clustering method can quickly generate interpreted images of Enteromorpha prolifera. The proposed framework in this paper can provide technical support for the early warning and disposal of Enteromorpha prolifera disasters.

Tightly coupled phased array antenna is a crucial form of ultra-wideband phased array antenna, which mainly consists of radiating elements, coupling capacitors between adjacent radiating elements, a wide-angle impedance matching layer on the array surface, and a reflective ground beneath the array. Its working principle is to decrease the resonant frequency of dipoles and counteract the inductive effect of the ground via the coupling capacitance between units, thereby attaining a low-profile and ultra-wideband impedance matching. Employ an equivalent circuit in conjunction with a Smith chart to elucidate the impedance frequency characteristics and physical significance of the various components within a tightly coupled phased array antenna. The functions and roles of different components of the antenna are deeply analyzed, and the key issues are summarized to provide theoretical guidance for the design of tightly coupled phased array antenna. Domestic and foreign design cases are summarized to provide experience for the theoretical design and engineering practice of this type of antenna.

The phased array wave spectrometer is a small incident angle real aperture radar in the Ku band that detects ocean waves. When detecting ocean waves, it obtains a one-dimensional ocean wave spectrum in that direction by accumulating the echoes in different directions illuminated by the antenna. When the radar ring scans a circle to obtain the two-dimensional wave spectrum results. During the echo accumulation time in a single direction, the observation geometry of the phased array wave spectrometer can be simplified to flying along a straight trajectory at a fixed squint angle. During this period, the movement of the platform and the bending of the wave front will cause range migration of the echo signal, resulting in a decrease in the detection accuracy of the phased array wave spectrometer. In response to this problem, this paper analyzes the range migration phenomenon that exists in the detection of phased array wave spectrometers, and proposes a correction algorithm for the range migration of phased array wave spectrometers. The algorithm is verified using airborne flight test data. Comparing the backscattering coefficient and two-dimensional wave spectrum obtained by the traditional inversion algorithm and the range migration correction inversion algorithm, and comparing the measurement results with the buoy measurement results respectively, the results show that the range migration correction algorithm can effectively improve the accuracy of the wave spectrum retrieved by the phased array wave spectrometer.