arXiv subjects

Liping Yan

Publications and source records attributed to Liping Yan.

7 recordsLinked to original sources

arXiv2026

An Adaptive Power Division Strategy for Nonlinear Components in Rectification

This letter presents a novel adaptive power division strategy, which uses two rectifying diodes with nonlinear impedance characteristics that are configured in parallel to function optimally at their individual power levels. Through the strategic adjustment of the input admittance, the conductance of the low-power diode decreases progressively with increasing power, while the conductance of the high-power diode increases correspondingly. This conductance-based power allocation method ensures that the power is rectified consistently by the most appropriate diode, regardless of the power level, and, thus, enables efficient rectification across an extended range. This letter presents a rectifier typology to substantiate the proposed strategy. Experimental results confirm the efficiency of the adaptive power division strategy, with the rectifier showing efficiency in excess of 60% from 5 to 29.5 dBm, giving a power dynamic range of 24.5 dB.

physics.app-ph↗

arXiv2025

Enhancing Microwave Heating Uniformity in Cavities Using a 2-bit Coding Metasurface

A novel method for enhancing microwave heating uniformity using a 2-bit coding metasurface is proposed. This metasurface is specially designed to scatter incident waves into multiple directions at 2.45 GHz rather than just one, significantly improving the electric field distribution uniformity within a cavity, and eliminating the need to redesign the cavity itself or modify the power excitation. Simulated results demonstrate a reduction in the coefficient of variation (COV) of potato temperature from 0.694 to 0.461, indicating enhanced heating uniformity while maintaining efficiency. Additionally, the measured potato temperatures show excellent agreement with the simulated results, validating the effectiveness of the proposed method.

physics.app-ph↗

arXiv2025

A Reconfigurable Circuit Strategy and Its Application in Low-Power Rectifier for Ambient Energy Harvesting

In ambient electromagnetic energy harvesting systems, the input power to the rectifier is low. To improve rectification efficiency, Schottky diodes, which are sensitive to low power, are commonly selected as rectifying devices to convert microwave power into dc power. However, low-power rectifying diodes typically have low reverse breakdown voltages, making them susceptible to reverse breakdown under high power conditions. This letter proposes a low-power rectifier with reconfigurable function. The rectifying diode is connected in parallel with the p-i-n diode. At low input power, the output dc voltage is low, and the p-i-n diode remains off, having no impact on the rectifier operation. As the input power increases, the p-i-n diode turns on, causing change in circuit structure and impedance mismatch. This leads to increased reflected power, thereby preventing the rectifying diode from receiving excessive power. In addition, the turn-on voltage of the p-i-n diode is lower than the reverse breakdown voltage of the rectifying diode, protecting it from reverse breakdown.

physics.app-ph↗

arXiv2025

Study on Improving Microwave Heating Uniformity Based on Phase-Frequency Simultaneous Modulation Technique

Conventional microwave heating techniques are limited due to inherent thermal point residency effects and inadequate control over the heating process. A novel method is proposed to enhance microwave heating uniformity using the injection-pulling technique. In this method, the injection-pulling technique is used to achieve simultaneous modulation of both the output phase and frequency of the magnetron, thereby extending the locking bandwidth of the injection-locking technique. The output characteristics of the injection-pulled magnetron were validated through numerical calculations and experiments. Microwave heating experiments were conducted under both a five-cup water load and an absorbent paper load. Compared with conventional injection-locking frequency sweeping, the proposed method not only expands the sweeping bandwidth from 8 to 18 MHz but also further improves heating uniformity, offering more options for magnetron applications in microwave heating.

physics.app-ph↗

arXiv2025

High-Efficiency Isolator-Free Magnetron Power Combining Method Based on H-Plane Tee Coupling and Peer-to-Peer Locking

Magnetrons are widely used as high-performance microwave sources in microwave heating, microwave chemistry, and microwave power transmission due to their high efficiency, low cost, and compact size advantages. However, the output power of a single magnetron is limited by its resonant cavities, posing a physical constraint. High-efficiency coherent power combining based on the injection-locking technique effectively overcomes this limitation and meets the demand for higher output power. Nevertheless, using isolators, such as circulators, introduces significant insertion loss, and the injection signal sources and phase shifters increase the system size, cost, and complexity in a conventional magnetron power combining (MPC) system. A novel method is proposed to utilize the coupling between two ports of an H-plane tee to achieve peer-to-peer injection locking magnetrons. Meanwhile, an asymmetric phase compensation is realized using a section of waveguide to adjust the magnetron output characteristics. Theoretical and numerical analyses provided qualitative insight into the system output behavior. Subsequently, an experimental system was developed for verification. In the experiments, the system achieved maximum microwave power combining efficiencies 90.2%, 93.6%, and 93.6% at electrical waveguide lengths corresponding to 90, 135, and 225, with output powers of 1650, 1260, and 1610 W, respectively, without the use of any isolators or external injection sources. The experimental results show good agreement with numerical calculations. This method offers the advantages of low cost, compact size, and low loss, providing a new approach for developing high-performance MPC systems in the future.

physics.app-ph↗

arXiv2025

Design of a High-Power and High-Efficiency GaN-HEMT VCO Based on an Inverse Class-F Amplifier

This letter proposes a high-power and high-efficiency GaN-HEMT voltage-controlled oscillator. The VCO consists of a coupled-line coupler, an inverse class-F amplifier, and a novel frequency-tunable stepped-impedance resonator. Using a harmonic control circuit and a parasitic parameter compensation circuit, the power amplifier operates in the inverse class-F state to achieve high efficiency. The feedback circuit uses a coupled-line coupler instead of the traditional coupling capacitor to control feedback power precisely. The measurement results show that the VCO with an oscillation frequency of 2.41-2.45 GHz achieves a maximum conversion efficiency of 74.5% at 2.44 GHz and an output power of 40.2 dBm. It is a candidate for the microwave source in a wireless power transmission system.

physics.app-ph↗

arXiv2024

Byzantine-Resilient Output Optimization of Multiagent via Self-Triggered Hybrid Detection Approach

How to achieve precise distributed optimization despite unknown attacks, especially the Byzantine attacks, is one of the critical challenges for multiagent systems. This paper addresses a distributed resilient optimization for linear heterogeneous multi-agent systems faced with adversarial threats. We establish a framework aimed at realizing resilient optimization for continuous-time systems by incorporating a novel self-triggered hybrid detection approach. The proposed hybrid detection approach is able to identify attacks on neighbors using both error thresholds and triggering intervals, thereby optimizing the balance between effective attack detection and the reduction of excessive communication triggers. Through using an edge-based adaptive self-triggered approach, each agent can receive its neighbors' information and determine whether these information is valid. If any neighbor prove invalid, each normal agent will isolate that neighbor by disconnecting communication along that specific edge. Importantly, our adaptive algorithm guarantees the accuracy of the optimization solution even when an agent is isolated by its neighbors.

eess.SY↗