Ke Han

A wideband pattern-reconfigurable antenna (PRA) integrating an asymmetric coplanar strip (ACS), coupled patches, and defected ground structure (DGS) loading is presented. The ACS provides the basic tilted-beam radiation, while the coupled patches and DGS provide complementary impedance-matching contributions in the upper and lower portions of the operating band, respectively. Their interaction with the original ACS response establishes three resonant responses that collectively broaden the matched band. The loading structures and two-PIN switching scheme are jointly designed to realize broadband radiation pattern reconfiguration, maintaining two selectable tilted-beam states across the wide operating band through a single feeding port. A prototype is fabricated and achieves a measured common −10 dB impedance bandwidth of 57.6%, covering 4.2–7.6 GHz. A radiation efficiency above 90% is obtained at the tested frequencies, and the measured radiation patterns generally maintain their overall tilted-beam shapes, with sidelobe levels more than 9 dB below the main beam. The proposed design provides a practical solution for broadband directional wireless applications requiring flexible coverage.

Wireless positioning technology is widely used in indoor positioning scenarios. However, in complex indoor environments, non-line-of-sight (NLOS) propagation introduces significant ranging bias and reduces the accuracy of anchor calibration. To address this problem, this paper proposes an adaptive robust UWB anchor calibration method assisted by channel impulse response (CIR). First, an NLOS identification network integrating a bidirectional gated recurrent unit (BiGRU), an attention mechanism, residual connections, and a ReLU feature-enhancement module is constructed to extract temporal features from CIR data and output the line-of-sight (LOS) probability of ranging observations. Then, the LOS probability is used as a measurement-confidence indicator and introduced into a factor graph optimization framework to construct an adaptive weight model, so that high-confidence observations receive larger optimization weights while the influence of low-confidence observations is effectively suppressed. This improves the robustness and accuracy of anchor calibration under complex obstruction conditions. Finally, the anchor position parameters are solved through nonlinear optimization. The proposed network achieves higher NLOS identification performance than the tested recurrent and convolutional baselines, and the confidence-assisted calibration method reduces the 3-D anchor calibration error in two obstruction scenarios. Calibration experiments further verify the effectiveness of the proposed method: under polystyrene-obstruction and wooden-obstruction scenarios, the calibration accuracy is improved by 47.6% and 37.9%, respectively, compared with the original method. The results indicate that the proposed method can effectively suppress the influence of NLOS errors on calibration results and provides a reliable solution for anchor calibration in complex indoor environments.

Accurate indoor localization is an important requirement in modern society. The fusion of ultrawideband (UWB) and inertial navigation is a commonly used positioning strategy. However, in complex environments, UWB observations may be blocked by obstacles or degraded by multipath, causing UWB outages and leaving the accumulated error of inertial navigation insufficiently constrained. To address this problem, this paper proposes an inertial-guidance-assisted UWB outage compensation algorithm based on a self-attention gated recurrent unit (SAT-GRU). The main innovation is to reformulate UWB outage compensation as a navigation-frame UWB position-increment prediction problem rather than direct absolute-position prediction or generic INS error regression. When UWB signals are available, IMU measurements together with extrapolated velocity and attitude are used to learn the temporal mapping to UWB position increments. When UWB signals are missing, the trained SAT-GRU adaptively weights informative motion segments in the IMU sequence and outputs pseudo-UWB increments for fusion localization. Field tests show that the proposed algorithm achieves a 68.75% improvement over pure inertial navigation, a 54.5% improvement over LSTM-based prediction, and a 64.3% improvement over GRU-based prediction, demonstrating the effectiveness and engineering applicability of the proposed method.

Accurate global navigation satellite system (GNSS) positioning in urban canyon environments is severely challenged by non-line-of-sight (NLOS) errors caused by signal blockage and multipath propagation. This paper proposes a novel GNSS localization framework that integrates three-dimensional (3D) light detection and ranging (LiDAR) perception with virtual grid-based differential correction to improve positioning performance for both multi-sensor receivers (core nodes) and surrounding low-cost GNSS devices (base nodes). First, an NLOS identification method is developed by combining LiDAR-based ray tracing with pseudorange innovation clustering, enabling reliable detection of mid- and high-elevation NLOS satellites. Then, a satellite selection strategy based on dilution of precision (DOP) optimization is proposed to balance NLOS error compensation and satellite geometry preservation. For cooperative localization, a dynamic virtual grid is constructed around the core node, and pseudorange observations are simulated to generate spatially correlated reference points, allowing base nodes to perform single-differenced positioning relative to the core node. Experimental results on the UrbanNav dataset demonstrate that the proposed framework significantly improves GNSS positioning accuracy and stability for the core node in complex urban scenarios. Meanwhile, it enhances the localization performance of nearby low-cost terminals through real-time environmental information sharing.

In indoor environments where Global Navigation Satellite System (GNSS) signals are entirely blocked, wireless signals such as 5G and Ultra-Wideband (UWB) have become primary means for high-precision positioning. However, complex indoor structures lead to significant multipath effects, which severely constrain the improvement of positioning accuracy. Existing indoor positioning methods rarely link environmental semantic information (e.g., wall, column) to multipath error estimation, leading to inaccurate multipath correction—especially in complex scenes with multiple reflective objects. To address this issue, this paper proposes a LiDAR-assisted multipath estimation and positioning method. This method constructs a tightly coupled perception-positioning framework: first, a semantic-feature-based neural network for reflective surface detection is designed to accurately extract the geometric parameters of potential reflectors from LiDAR point clouds; subsequently, a unified factor graph model is established to multidimensionally associate and jointly infer terminal states, virtual anchor (VA) states, wireless signal measurements, and LiDAR-perceived reflector information, enabling dynamic discrimination and utilization of both line-of-sight (LOS) and non-line-of-sight (NLOS) paths. Experimental results demonstrate that the root mean square error (RMSE) of the proposed method is improved by 32.1% compared to traditional multipath compensation approaches. This research provides an effective solution for high-precision and robust positioning in complex indoor environments.

This paper demonstrates an integrated wide-angle scanning planar phased array based on pattern reconfigurable antennas. The pattern reconfigurable antenna unit consists of four rotationally symmetrical elements with a dimension less than 0.41λ×0.41λ. By exciting different elements, the beam of the unit switches between four modes and has a 3dB coverage of ±77°, which helps the antenna array achieve an expanded scanning range. The reconfigurable principle and bandwidth enhancement method of the compact antenna unit are analyzed; the radiation efficiency and the performances of the array are also discussed. The whole system of the phased array is integrated on a multilayer hybrid PCB board, which includes a 4×4 reconfigurable antenna array, TR modules, 4-channel RF chips, a beam control circuit, and a power management circuit. The measured return loss of the antenna unit is less than -10dB in the frequency range of 27GHz to 30GHz, and the scanning range is from -68° to 68° with a maximum gain of 16.4dBi. The gain fluctuation of the array in beam scanning is less than 2dB, and the scanning range of -3dB covers ±80°.

This article presents a SIW-based dual-polarized 2-D monopulse scalable antenna array in the millimeter-wave (MMW) scenario. To obtain similar radiation characteristics for dual polarization over a wide bandwidth, a symmetric magnetoelectric (ME) dipole cavity-backed antenna is designed. A $\mathbf{T}{{\mathbf{E}}_{140}}$ mode feeding cavity is utilized to make the array scalable. The cascades of magic tees enable this dual-polarized array to achieve sum-difference beamforming in two dimensions. To validate our idea, a 4×4 antenna prototype was manufactured and tested. The measured overlapped bandwidth for eight ports reaches 23.02% (33.45 GHz-42.15 GHz). The gains of the sum, difference, and bi-difference beams reach 19.4 dBi, 16.1 dBi, and 13.4 dBi, and their null depths are greater than 31 dB.

In this letter, an enhanced-bandwidth multibeam antenna based on center-fed linear slot array is proposed. First, by placing the coupling slot in the center and inserting matching vias, the proposed center-fed method can enhance the bandwidth by exciting slots of linear slot array in phase in an enhanced bandwidth. To illustrate the operation principle, the electric fields of center-fed structure and the function equations among the phase, distance, and frequency are analyzed and presented. Then the multibeam application of the center-fed linear slot array with 4 × 4 Butler matrix beamforming network is fabricated and measured. The measured impedance and 3-dB gain bandwidths are 13.69% and 14.09%. When exciting different ports, the beam angles fluctuate around -38°, -20°, 20°, and 40°, with peak gains of 16.66, 17.65, 17.74, and 16.88 dBi