To improve the anti-interference for ELF/VLF communication based on modulated heating lower-ionosphere, chirp spread spectrum technology with strong anti-interference is combined with square wave amplitude modulation, a novel method of chirp-BOK modulated heating lower-ionosphere is proposed in this paper. On this basis, to improve the radiation efficiency of ELF/VLF, the effects of heating parameters (effective radiation power, pump frequency, polarization mode, modulation frequency, duty cycle, and bandwidth) on the radiation efficiency of ELF/VLF were analyzed. The results show that the radiation amplitude of ELF/VLF increases with the increase of effective radiation power, while the radiation efficiency increases first and then decreases; the X-mode is better than the O-mode; the radiation intensity of ELF/VLF decreases with the increase of pump wave frequency from 4MHz to 10MHz; the ELF/VLF equivalent dipole moments increase with the rise of modulation frequency from 500Hz to 5kHz; with the change of duty cycle from 10% to 90%, the dipole moments first increase and then decrease, and the optimal range of duty cycle is 40% to 70%; with the increase of bandwidth, the dipole moments are unchanged. Furthermore, the ELF/VLF dipole moments of square wave amplitude modulated heating ionosphere is unchanged before and after the chirp spread spectrum.

中文翻译：

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基于chirp-BOK调制加热的低电离层激发ELF/VLF波参数优化理论分析

为提高基于调制加热低电离层的ELF/VLF通信的抗干扰性，将抗干扰强的chirp扩频技术与方波调幅相结合，提出了一种chirp-BOK调制加热低电离层的新方法在本文中。在此基础上，为提高ELF/VLF的辐射效率，分析了加热参数（有效辐射功率、泵浦频率、极化模式、调制频率、占空比和带宽）对ELF/VLF辐射效率的影响。结果表明，ELF/VLF的辐射幅度随着有效辐射功率的增大而增大，而辐射效率先增大后减小；X模式优于O模式；ELF/VLF的辐射强度随着泵浦频率从4MHz增加到10MHz而降低；ELF/VLF等效偶极矩随着调制频率从500Hz升高到5kHz而增加；随着占空比从10%到90%的变化，偶极矩先增大后减小，占空比的最佳范围为40%～70%；随着带宽的增加，偶极矩不变。此外，方波调幅加热电离层的ELF/VLF偶极矩在啁啾扩频前后没有变化。占空比的最佳范围为40%～70%；随着带宽的增加，偶极矩不变。此外，方波调幅加热电离层的ELF/VLF偶极矩在啁啾扩频前后没有变化。占空比的最佳范围为40%～70%；随着带宽的增加，偶极矩不变。此外，方波调幅加热电离层的ELF/VLF偶极矩在啁啾扩频前后没有变化。