Liang Xu

Simulations have shown that the ε-negative metamaterial-based magnetic enhanced reflectarray antenna (MERA) element has comparable power handling capacity (PHC) to all-metal high-power microwave (HPM) antennas. This demonstrates the potential of microstrip antennas in the HPM field. Although an X-band MERA prototype has been designed that achieves high radiation performance, there has been no suitable method to evaluate its PHC characteristics. This paper presents the design and fabrication of an experimental HPM platform operating at 9.4 GHz to verify the prototype’s PHC, as well as the results of HPM experiments. This work experimentally demonstrated the feasibility of applying MERA to the HPM field. The experimental results indicate that the designed MERA remains stable under HPM illumination and confirm that the PHC of the MERA element reaches 1 GW/m2. These results are important for advancing microstrip antenna development in the HPM field.

In this letter, a phase synthesis method for mechanical beam scanning based on the feed displacement technique (FDT) is proposed for reflectarray antennas. To verify the correctness of the optimization method, the high-performance magnetic enhanced reflectarray antenna (MERA) element is used, which has a cross-polarization level consistently less than -30 dB in the range of 9.2-9.8 GHz and the reflection phase remains essentially constant in the range of 0-45° incidence angle. Using this element, an FDT-based MERA prototype was designed and fabricated. The prototype was able to maintain a gain variation of less than 1 dB within a beam scanning range of ±40° and no more than 3 dB over ±55°, achieving a maximum aperture efficiency of 64.85% in its operating band. The proposed method is applicable to simplify the beam scanning system and improve the scanning performance of reflectarray antennas.

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.

A beam-steerable wideband reflectarray antenna (WRA) for C -band high-power microwave (HPM) application is presented in this paper. The C -band WRA is made up of a multimode conical horn antenna with high power handling capacity (PHC), 25×25 special designed antenna elements, a metal frame and a dielectric plate as radome. In our previous work, it has been verified that a wideband prototype using this antenna element has a relative bandwidth of 50% (3.3-5.5 GHz) and its beam scanning range reaches ± 60° in low power experiments. In this paper, combined with the equivalent circuit model, the wideband and high PHC property of the WRA element is further explained. To demonstrate the excellent performance of the proposed element in HPM applications, we combined the C -band WRA (which is different from the previous wideband prototype after redesigning) with a well-designed narrowband HPM source operating at 4.3 GHz and constructed a matching HPM experimental platform. The C -band WRA works at 4.1-4.5 GHz, and the results of low power experiments indicate that it can maintain good performance during beam scanning. Its sidelobe level and cross-polarization level are always less than -15 dB and –22 dB, respectively, while its maximum aperture efficiency reached 68.99% (the corresponding antenna gain is 28.07 dB at 4.3 GHz). On the other hand, the PHC of the WRA element reaches 3.82 GW/m ² while the C -band WRA reaches 1.24 GW in simulation. HPM verification experiments have been carried out, and the experimental results show that the PHC of the fabricated prototype exceeded the expectation, which proves that the WRA has broad application prospects in HPM fields.

A beam-steerable wideband reflectarray antenna (WRA) is presented in this communication. The WRA element operated at 3.3-5.5 GHz (relative bandwidth 50%) exhibits a continuous 360° phase coverage and its power handling capacity (PHC) is estimated to exceed 4.5 GW/m ² in simulation, indicating its potential in high-power microwave (HPM) applications. Moreover, to verify the wideband performance of the WRA, a prototype was successfully designed, simulated, fabricated, and measured in S and C bands. The WRA prototype is composed of an ultra-wideband helical feed antenna, 25×25 antenna elements, and a dielectric plate as a radome. The results show that in the frequency band of 3.3-5.5 GHz, the WRA can achieve arbitrary direction of reflection beam within ±60° (120° conical region). Additionally, at the center frequency of 4.4 GHz, its sidelobe level is consistently below -15 dB, while the maximum gain loss is 3.3 dB during beam steering, and the maximum aperture efficiency reaches 67.89% in the direction of θ ₀ =0° and φ ₀ =0°.

An all-metal reflectarray (RA) element based on the variable-rotation technique (VRT) is presented in this letter. The RA element, based on an elliptical inner conductor and a circular outer conductor, exhibits a continuous 360° phase coverage with negligible element loss over a wide range of incident angles and frequencies. A 10GHz prototype with 121 manually rotated elements was simulated, fabricated and tested. The proposed RA antenna has 2-D beam-steerable capability up to 45° elevation angle. The measured results agree well with the simulated counterparts. For demonstration, four different steering cases are presented as examples by manually adjusting the rotation angle of the RA elements. The maximum measured antenna gain is 26.2dBi, corresponding to an aperture efficiency of 66%. A 1.3 dB gain drop was measured during beam scanning from 0° to 40°.

A beam scanning antenna based on an all-metal lens is presented for high-power microwave (HPM) application in this paper. This design includes a feed antenna and two layers of different all-metal lenses, whose prototypes operating at 14.25 GHz have been successfully designed and fabricated with an aperture radius of 300 mm. A full transmission phase range of 360° can be achieved with a transmission efficiency of over 99% by rotating the cross-slot on the lens elements. The results of the low-power tests depict that the designed antenna can realize a beam scanning range of 120° revolving cone angle with the side lobe below −10 dB and the reflection coefficient less than −16 dB. The high-power tests demonstrate that the power handling capacity of the antenna is higher than 350 MW in sulfur hexafluoride (SF₆). In addition, both the designed lenses have a bandwidth of more than 100 MHz. All the merits show that our designed all-metal lens antenna has a great potential to be applied in HPM systems.

To solve the problem of the large axial size of high-power microwave (HPM) reflectarray antenna and difficulty in vacuum packaging, a dielectric is introduced in the design of the antenna element. On this basis, a dielectric embedded metasurface reflectarray antenna (DEMRA) with high power handling capacity and wide-range beam scanning capability is proposed and fabricated. Compared with traditional HPM antennas, the DEMRA does not need to be sealed and can work directly in open-air conditions. The DEMRA can realize free regulation of the radiation beam within a cone angle of 90° and has a power handling capacity of 1 GW/m2. As verification, a protype working at 10 GHz is fabricated and low-power experiments are carried out. Experimental results are consistent with the simulation, proving that the DEMRA has a bandwidth exceeding 600 MHz. During the scanning process, the aperture efficiency is always higher than 48.98%, and the side lobe level remains below −15 dB. At the same time, the cross-polarization component is less than −15 dB, while the main lobe-axis ratio remains within 4.5 dB, confirming its beam scanning capability.

In circular waveguides, the TE₀₁ mode has the lowest transmission loss, which is very suitable for long-distance transmission of high-power microwaves (HPMs). The output mode of HPM sources is mainly the TM₀₁ mode; however, there are few research studies on mode converters of TM₀₁-TE₀₁. In this paper, a high efficiency HPM TM₀₁-TE₀₁ mode converter is designed; compared with the traditional TM₀₁-TE₀₁ mode converters, the structure of the mode converter is compact and easier to process. It is mainly composed of an input circular waveguide, a tapered rectangular waveguide, a 90° bent rectangular waveguide, and an output circular waveguide. A prototype with a center frequency of 2.4 GHz is fabricated and HPM experiments are carried out. The transmission efficiency of this device reaches 99.8% in the simulation, and the measured transmission efficiency is more than 98%. Additionally, the measured power handling capacity is more than 1 GW, which is consistent with simulation. This design has important reference significance for the design of long-distance power transmission devices and HPM mode converters.