Shengren Peng

Gigawatt-class radiation generated by a Ka-band overmoded Cherenkov-type high power millimeter wave generator

Particle simulation and experimental results are presented about a Ka-band overmoded Cherenkov-type high power millimeter wave generator in this paper. The relativistic electron beam with peak current of 8.4 kA was generated by a pulsed power accelerator working at the voltage of 625 kV, which was guided by an axial magnetic field of 1.05 T and transported through the beam-wave interaction structures. After careful calibration, the microwave power radiated in the far field was as high as about 500 MW, with a frequency of 32.1 GHz and a pulse width of 20 ns. The radiation mode was well controlled to be TM(0n) mode.

Design of a Concentric Array Radial Line Slot Antenna for High-Power Microwave Application

A compact concentric array radial line slot antenna (CA-RLSA) operating at Ku-band for high-power microwave (HPM) application is proposed in this paper. The efficiency of HPM-RLSA becomes lower as the aperture size reduces due to rotational asymmetry of the illumination. The HPM-CA-RLSA was designed to overcome this difficulty with notable power handing capacity. It is fed by circularly polarized TE11 coaxial waveguide mode to generate a rotational symmetric cylindrical wave excitation. Furthermore, the reflection canceling structure of this HPM-CA-RLSA is not only simpler than the one in the HPM-RLSA but also improves the frequency response performance. An antenna prototype with length of 8 cm and aperture diameter of 40 cm is designed, which has a gain of 32.0 dBi, reaching an aperture efficiency of 62.7%, and an axial ratio less than 0.5 dB at 12 GHz. The simulated results show that this antenna has a power handing capacity of more than 500 MW.

Solution to GW TEM-Circular Polarized TE 11 Mode Converter Design for High Frequency Bands

The solution utilized to design a compact transverse electromagnetic mode (TEM)-CPT (circular polarized TE11) mode converter with high power handling capability and high efficiency, especially at high frequency bands is proposed in this paper. The analysis shows that increasing the quantity of the arms of the converter could make the converter work under overmoded state. The problem that the power capability of the converter working at high frequency bands is low will be addressed. To verify the feasibility of this solution, simulations and experiments on a 20 arms converter are carried out, and the results show that the converter would convert the TEM mode into CPT mode efficiently in a 2–3 free wavelengths longitudinal size and that the power capability is in gigawatt (GW) class. Moreover, this kind of converter can also be utilized in the design of GW TEM phase shifter, whether at low or high frequency bands, which plays a key role in the power combining technology.

All-Metal Transmit-Array for Circular Polarization Design Using Rotated Cross-Slot Elements for High-Power Microwave Applications

Transmit-array (T-A) design for circular polarization made by all metal is presented in this communication. The proposed T-A consists of numerous cross-slot elements. The simulation results indicate that rotating the cross slot on the element, a full transmission phase range of 360° can be achieved for a transmission magnitude better than −0.6 dB at 9.375 GHz. A T-A has been designed, simulated, and measured in x-band. The measurement results show that the T-A can radiate the wave in the desired direction with an enhanced gain. They are in agreement with the theoretical and simulation results. Furthermore, the all-metal T-A presented in this communication has the application potentials for high-power microwave applications.

GW TEM-Mode Phase Shifter for High-Power Microwave Applications

In this paper, a gigawatt (GW) transverse electromagnetic wave (TEM)-mode phase shifter (TPS) used to adjust the phase of output of high-power microwave is investigated. The phase shifter is composed of two identical coaxial TE11 circular polarizers, and can adjust the output microwave phase in a range of 0°-360°. The electrical behaviors are analyzed in theory and simulated by the CST software, the results show that the TPS at frequency 1.79 GHz can adjust the microwave phase in a range of 0°-360°, the transmission in this range of phase-shifting process is over 97.5%, and the power-handling capacity is as high as 5.3 GW.

All-Metal Beam Steering Lens Antenna for High Power Microwave Applications

All-metal beam steering antenna based on the concept of Risley prism is presented in this communication. The antenna is composed of a feed antenna and two metal lenses. Mechanically rotate two lenses along the same axis independently can steer the radiation beam in both azimuth and elevation planes. Simulations and measurements were carried out in X-band to verify its performance, and the results agree each other well, which are also in agreement with the theoretical results. Furthermore, the power handling capability of the lens antenna with a dimension of

A Novel

1~\text {m} \,\, \times \,\, 1 \,\, \text {m}

\text{TM}_{0{n}}

is estimated about 4 GW, which indicates the all-metal beam steering antenna has the application potentials for high-power microwave applications.

Mode Content and Relative Phase Analysis Technique

Overmoded relativistic backward wave oscillators (RBWOs) are usually difficult to achieve pure mode ouhowever, until now, radiation equipments for high power microwave (hPM) devices are only matched to a single operating mode. So it is unsuitable to utilize the ready-made hPM antenna to radiate mixed TM0n modes with high radiation efficiency, and thus practical applications of the overmoded RBWO device becomes limited. For converting these hybrid TM0n modes into a pure one (e.g., TM01 or TEM mode), diagnostics of the overmoded RBWOs output mode is required. In this letter, a practical measurement technique without requiring high precision calibrations of the power distribution and relative phases between the TM0n modes propagating in overmoded waveguide is described. This method is validated by measuring the output modes of a specially designed TM01-TM0n mixed modes exciter.

Reflection measurement of waveguide-injected high-power microwave antennas

A method for reflection measurements of High-power Microwave (HPM) antennas excited with overmoded waveguides is proposed and studied systemically. In theory, principle of the method is proposed and the data processing formulas are developed. In simulations, a horn antenna excited by a TE11 mode exciter is examined and its reflection is calculated by CST Microwave Studio and by the method proposed in this article, respectively. In experiments, reflection measurements of two HPM antennas are conducted, and the measured results are well consistent with the theoretical expectations.