Yunfei Sun

A new topology to excite the circular TM₀₁ mode for high-power microwave (HPM) research is provided. Three important innovations enhance its transmission performance: a four-aperture sidewall coupling structure for parasitic mode suppression, an intermediate coaxial TEM mode stage for bandwidth extension, and a four-way stacked power divider for compactness. Measurement results show that within the frequency range of 7.5–11.5 GHz (relative bandwidth of about 42.1%), the converter exhibits an insertion loss less than 0.4 dB, a return loss better than 15 dB, and a mode purity higher than 96.7%. The converter features broad bandwidth, high conversion efficiency, and high mode purity, making it suitable for cold-test experiments of HPM sources and high-power transmission components.

A novel topological structure and design methodology for a rectangular fundamental TE₁₀ to circular TE₀₁ mode converter is presented in this article. The transmission performance is substantially improved through three key innovations: 1) the implementation of an eight-aperture sidewall coupling structure effectively suppresses higher-order parasitic modes; 2) the introduction of a composite impedance-matching scheme significantly broadens the operating bandwidth; and 3) the integration of an eight-way stacked power division network further enhances structural compactness. The analysis of the mode conversion principle, numerical simulations, fabrication, and experimental measurement of the X-band prototypes are described. Back-to-back measurement results exhibited good agreement with simulation prediction. Measurement results indicate that within the frequency range of 7.9–12.2 GHz (relative bandwidth of 42.8%), the converter exhibits an insertion loss less than 0.35 dB, a reflection coefficient lower than −16 dB, and a mode purity higher than 99.3%. The overall longitudinal length is only $4.5\lambda _{0}$ (where $\lambda _{0}$ is the wavelength at 10 GHz). This converter supports modular layered precision manufacturing and demonstrates clear advantages in broadband performance, high conversion efficiency, and structural compactness.

This letter proposes a novel ultra-wideband (UWB) plate antenna design that achieves significant improvements in both bandwidth and radiation performance by combining air-filled patch antennas with floating resonators. Shorting pins on the radiator and an intermediate split structure are employed to suppress H-plane pattern splitting and sidelobes caused by the suspended plate structure. Additionally, dual multilayer resonators are strategically embedded within the antenna to generate wideband resonances, improving impedance matching and mitigating degradation from higher-order mode radiation. To validate this approach, the antenna was designed, fabricated, and tested. The antenna dimensions are 122 mm (0.77$\lambda _{0}$) × 120mm (0.76$\lambda _{0}$) × 35mm (0.22$\lambda _{0}$), with an operating frequency range of 0.94GHz to 2.88GHz (101.5$\%$ bandwidth). The design demonstrates effective sidelobe suppression, a compact structure, and stable radiation patterns, addressing the issue of insufficient operating bandwidth in traditional plate antennas and showing its potential for wideband UWB communication and radar applications.

This letter presents a novel rotary high-power microwave (HPM) phase shifter (PS) featuring a unique zigzag-shaped transmission channel formed within a metallic cavity and a metallic rotor assembly, which can achieve broad bandwidth simultaneously with high power-handling capacity and linear phase shift. The PS is based on the principle of tunable electrical length and can shift phase by turning the metallic rotor. A prototype of the rotary waveguide PS in the X-band has been designed, fabricated, and measured. The measured results show that the PS can shift phase linearly over 360° across the band 8.2–11.7 GHz, with the return loss (RL) higher than 18 dB, the insertion loss (IL) below 0.6 dB, and the measured rms phase shift errors not exceeding 1.5°. Thereby, the device exhibits excellent performance with a record-high relative bandwidth reaching 35.2%.

In this article, a compact TM^∘₀₁ to TE^∘₀₁ (symbol ○ represents the circular waveguide) mode converter for X-band high-power microwave (HPM) applications is designed, fabricated, and experimentally verified. The proposed device comprises three parts, which are a TM^∘₀₁ to vertical polarization (VP) TE$^{\text{\tiny$7. (symbol □ represents the rectangle waveguide) mode power divider, a horizontal polarization (HP) TE$^{\text{\tiny$10. to TE^∘₀₁ mode power combiner, and an N-way TE$^{\text{\tiny$13. circumferential array polarization torsion structure (CA-PTS). The first two parts utilize the topologic structures of radial power dividers (RPDs), which are then connected by the CA-PTS. This novel methodology makes the input and output ports of the mode converter on the same axis, with the transverse and longitudinal dimensions of approximately 8.6λ₀ and 3.5λ₀, respectively. Simulation results of the TM^∘₀₁ to TE^∘₀₁ mode converter demonstrate that the return loss is better than -15.0 dB from 8.28 to 8.74 GHz, while the insertion loss remains below -0.2 dB, and a remarkable conversion efficiency achieves 99.21% at the center frequency of 8.4 GHz. An 18-way prototype was subjected to experiments. The measured S-parameter results of the setup were in good agreement with simulation one. Under an input power of 0.5 W, the simulated maximum internal electric field measured 943 V/m, and the power handling capacity (PHC) was also validated in the HPM test.

Measuring the pointing angles of high-power microwave (HPM) helical array antennas presents significant challenges, resulting in a lack of effective angle control schemes in current research. To address this issue, this study proposes a near-field pointing detection method that utilizes dipole antennas for closed-loop control of HPM helical array antenna positioning. The evaluation results obtained via interpolation methods show that the absolute angle error is less than 0.701$^\circ$. In addition, this work also conducted closed-loop control experiments on HPM helical array antennas based on proportional- integral-derivative (PID) control algorithm. Compared to conventional open-loop control systems, the proposed closed-loop control strategy produces a control curve that closely aligns with the theoretical calculation curve, realizing lower steady-state error and improved system robustness.

A continuous transverse stub (CTS) array antenna with broad bandwidth and high-power handling capacity is proposed in this paper. The technologies of multi-step impedance matching and T-shaped electromagnetic band-gap (EBG) loading are utilized, which improved the antenna operating frequency bandwidth. An H-plane lens horn is used to feed the CTS array. As a result, a good bandwidth capability of more than 32% is achieved, with a gain variation less than 3.0 dB. The measured sidelobe level (SLL) is below −18 dB in the entire frequency range. Moreover, the power handling capacity of the antenna is more than 80 MW and can reach the GW level after arraying, which indicates that this antenna has application potential in the high-power microwave (HPM) field.

A magnetic-enhanced reflectarray antenna (MERA) based on ε-negative (ENG) metamaterial is proposed in this communication. By utilizing the variable-rotation technique (VRT), the MERA achieves the first-ever application of the ε-negative metamaterial in a high-power microwave (HPM) reflectarray antenna (RA) under passive conditions. The antenna element of the MERA is a tri-layer structure composed of an ENG layer sandwiched by two high-ε _r dielectric slabs, with a metal sheet situated at the bottom of the sandwich structure to reflect incident waves. Operating in X -band (8.6-9.8 GHz), the MERA element exhibits a continuous 360° phase coverage with negligible element loss and robustness against the incident angle, with an estimated power handling capacity (PHC) exceeding 1 GW/m ² . Using the proposed element, a prototype focused in the direction of (θ ₀ =20°, φ ₀ =0°) was fabricated and experimented, and the simulation results were found to be in good agreement with the measured results. The measured results indicate that the MERA has an aperture efficiency greater than 53.4% within the operation bandwidth, with the maximum value reaching 64.33%, while achieving sidelobe levels of less than -20 dB.