Design And Simulation Study Of S-Band Milo-Based Radiation System

Abstract

Magnetically insulated line oscillator (MILO) is a renowned high-power microwave (HPM) device having an inherent property of self-insulating magnetic field. In this paper, an HPM system based on S-band MILO, TM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> - TE <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> mode converter and axial corrugated horn antenna, is designed and simulated numerically. MILO is simulated using CST with Particle-in-Cell (PIC) method. In S-band MILO, a design modification in the form of tapered extraction region is made for efficiency enhancement. Simulation results show that when diode voltage of 420kV and beam current of 45kA is applied, a 3.4 GHz high power microwave of dominant TM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> mode with 2.1GW peak power and the peak power efficiency of 11.11% is generated. TM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> mode produces bore-sight null in radiation pattern of far field. In order to produce peak power at bore sight, a metal-based circular sectoral waveguide (CSWG) TM <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</inf> - TE <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> mode converter is simulated using CST Microwave Studio. This mode converter has features of design linearity, low weight, less complex structure and good mode conversion efficiency. The simulated mode converter has 97.6% mode conversion efficiency at 3.4GHz and over the frequency range 3.39-3.41GHz it is more than 90%. For radiation pattern symmetry and low sidelobe level, an axial corrugated horn antenna is designed and simulated for MILO. This antenna has gain of 19.2dBi at bore-sight, cross polarization less than −35dB and reflection coefficient less than −23dB at 3.4 GHz. For E-plane and H-plane, −3dB beam width is 20° and 18.8°, respectively, and sidelobe level is less than −30dB.