用于探地雷达的超宽带发射源的研究与设计

发布时间：2018-09-18 18:38

【摘要】：探地雷达是用无线电波来确定地下介质分布的一种无损探测方法,通过发射天线向地下发射电磁波,电磁波在地下不同介质的分界面处发生反射,通过接收天线接收反射回地面的电磁波,根据电磁波的波形、振幅强度和时间的变化等特征推断地下介质的具体情况。现在探地雷达的应用领域越来越广泛,本文针对传统探地雷达的信号源频率较低、频带较窄等问题加以改进,以适应更加广阔的市场。本文研究的信号源采用锁相环技术,锁相环主要包括鉴相器、环路滤波器和压控振荡器三个模块,其中压控振荡器是整个锁相环的关键,影响到调谐带宽、输出功率和相位噪声等诸多因素。本文从振荡器的基础理论出发,针对超宽带压控振荡器的技术指标要求,通过合理选择压控振荡器的电路结构,设计了1-2GHz和2---4GHz两个频段相连的超宽带压控振荡器。最后,论文设计了锁相环的其它模块并接入压控振荡器,测试了锁定输出频率的相位噪声。L波段的压控振荡器是根据Colpitts反馈振荡电路的理论,采用串联谐振网络设计而成,测试结果显示,此振荡器的调谐频率范围是1-2GHz,基本满足了设计指标要求,而输出功率范围是-6--2dBm,与设计指标有一定的差距；S波段的压控振荡器是根据负阻反馈模型的理论,采用并联谐振网络设计而成,测试结果显示,此振荡器的调谐频率范围是2-3.7GHz,输出功率范围是2.2-3.3dBm,基本上都满足了设计指标要求：两个压控振荡器对应的锁相环经过测试,在中心频率1.5GHz和3.1GHz处锁定之后的相位噪声分别为-89.13dBc/Hz@100KHz和-85.6dBc/Hz@100KHz,基本满足了设计指标要求。
[Abstract]:Ground penetrating radar (GPR) is a nondestructive detection method for determining the distribution of underground media by radio waves. The electromagnetic waves are reflected at the interface of different underground media by transmitting antennas to the ground. Through receiving the electromagnetic wave reflected back to the ground by receiving the antenna, the concrete condition of underground medium is inferred according to the characteristics of electromagnetic wave waveform, amplitude intensity and time. Nowadays, the application of GPR is more and more extensive. In this paper, the signal source frequency and frequency band of traditional GPR are improved to adapt to the broader market. The phase locked loop (PLL) technology is used in this paper. The PLL consists of three modules: phase detector, loop filter and VCO. The VCO is the key of the PLL, which affects the tuning bandwidth. Output power and phase noise and many other factors. Based on the basic theory of the oscillator and the technical requirements of the ultra-wideband voltage controlled oscillator, this paper designs an ultra-wideband voltage controlled oscillator with two frequency bands, 1-2GHz and 2-4GHz, by reasonably selecting the circuit structure of the voltage controlled oscillator. Finally, the other modules of the PLL are designed and connected to the VCO. The phase noise. L-band VCO with locked output frequency is designed by using the series resonant network according to the theory of Colpitts feedback oscillation circuit. The test results show that the tuning frequency range of the oscillator is 1-2GHz, which basically meets the design requirements, while the output power range is -6-2dBm. the VCO, which has a certain gap with the design index, is based on the theory of negative resistance feedback model. The experiment results show that the tuning frequency range of the oscillator is 2-3.7GHz and the output power range is 2.2-3.3dBm. it basically meets the requirements of the design: the phase-locked loop corresponding to two voltage-controlled oscillators has been tested. The phase noise after locking at the center frequency 1.5GHz and 3.1GHz is -89.13 dBc / Hzr 100kHz and -85.6 dBc / Hz100KHz respectively, which basically meets the design requirements.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN959

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