Design and simulation of a broadband microwave noise source with high ENR based on a gyro-TWT

This article designs a high-power broadband random noise source based on a Ku-band gyrotron traveling wave tube (gyro-TWT) with a bandpass Bragg filter. The linear lossy dielectric-loaded circuit of the gyro-TWT is long enough to achieve sufficient electron pre-bunching and modulation to excite extremely broadband noise floor signals without any external input. They will be further amplified to high power in the nonlinear beam–wave interaction circuit. A bandpass Bragg filter integrated with the tube is designed for frequency selection and improving noise amplification on the sideband for better signal flatness. The gyro-TWT is driven by a gyrating electron beam with a voltage of 60 kV, a current of 20 A, and a pitch factor of 1.2. Particle-in-cell simulation shows that the noise source can achieve an output power above 28.81 kW in the frequency range of 11.55 ∼ 18.1 GHz. The excess noise ratio (ENR) is up to 80 dB with an envelope average flatness of ± 20 dB. The probability density function approximately satisfies a Gaussian distribution with a mathematical expectation of 1.5 × 10−3 and a standard deviation σ of 166. The generated high-power broadband random noise will have potential applications in noise radar, electronic countermeasures, and secure communication.