Design And Implementation Of Transmitting Module For Nonlinear Target Detector

In recent years,due to the development of MMIC and HMIC technologies and the continuous improvement and evolution of various chip processes,miniaturization has become one of the important trends in the development of electronic equipment.On the one hand,this trend has brought a lot of convenience to people's daily lives,and it has provided more research tools for scientific researchers in certain fields,but on the other hand,it has also brought more pressure on areas such as security and confidentiality.Affected by the harmonic re-radiation characteristics of a non-linear target,when an unshielded non-linear target is illuminated by external electromagnetic waves,the target's scattered wave contains harmonics.However,a linear target under the same conditions will only scatter out fundamental waves with the same frequency as the incident wave.The non-linear target detector is based on this characteristic,and realizes high anti-interference detection of various non-shielded electronic equipment including non-linear devices.This thesis starts with the application of non-linear target detectors,introduces their general classification and development trends,and shows the significance of further research on them.Furthermore,the basic characteristic equations of the non-linear target and the nonlinear detector are derived,and the indicators and schemes of the front-end transmitting module of the non-linear target detector designed this time are determined by combining several types of typical transmitter architectures and corresponding performance indicators.The specific implementation scheme includes three major parts: passive module design and selection,active module design and selection,and PCB design and processing and welding.In the design of the passive part,the transceiver microstrip antenna,microstrip low-pass filter,low-temperature cofired ceramic low-pass filter,fixed-value attenuator and ceramic capacitor were analyzed,designed,and selected in turn.The design of the active part has theoretically analyzed and selected the frequency source,RF driver amplifier,RF power amplifier and voltage-controlled attenuator in turn.PCB design is based on RF PCB drawing rules to meet signal integrity and EMC requirements as much as possible.After the overall design of the transmitting module was completed,separate tests of the transmitter circuit and comprehensive testing of the actual working performance of the transmitter circuit in the whole detection system were performed in turn.The results show that the designed transmitting module works well in the system.The signal output power of each frequency point is greater than 40.3dBm.The second harmonic suppression is better than 112.4dBc,and the third harmonic suppression is better than 106.3dBc.The phase noise is better than-79.9dBc/Hz@10KHz.The Phase discrimination leakage spurious suppression is better than 64.5dBc.The performance basically meets the expected design index.Finally,some typical problems and solutions in the design and testing process are proposed,and the full text work is summarized,and the deficiencies that can be further improved in the design are put forward.