The Research Of Broadband Pulse Detector For 18-40GHz

The detector plays an important role in millimeter-wave systems. By now the studies of detectors in China are mostly put emphasis on TSS(tangential sensitivity),VSWR(voltage standing wave ratio) and so on. The thesis aims to design a detector of ns order for response time. And the detector works in the linear detection area with pulse detection.In this thesis, the elementary theory and the development of detectors are introduced. HSCH-9161, the zero bias beamlead detector diode of Agilent company is chosen as the detector diode in circuits. The author adapts parallel and series solutions to design detection circuits. Size of microstrips are set to be variables. And these parameters are simulated and optimized to achieve the best goals of VSWR of circuits.Substrate fabrication and the test works are in procession on the basis of the previous work in end.The thesis introduces elementary knowledge of millimeter-wave, pulse signal,detector diode, detection principal and so on.The software, ADS is used to meet the demand of broadband impedance match and the whole circuits optimization. HFSS is used to optimize the LPF(low pass filter) model. And the waveguide to microstrip transition is simulated in CST. Main work, which is the most difficult part of circuits, is the impedance match of detector diode. Considering the frequency of circuit(18-40GHz),a certain loss is allowed in designs. Thus it can both take TSS and VSWR in consideration. Optimization results of VSWR in all circuits are less than 1.5, and the response time of detectors is in ns order. The test data of series detector for K- and Ka-band shows that the detector’s response time is less than 1 ns. Detector work in linear detection area and realize pulse detection well. But the VSWR is not meet demand in the whole band..VSWR of Ka-band detector is bigger than 2.5 in the lower frequency band. And it works in pulse detection. Response time is not given out here.As to parallel detector the VSWR is less than 2.5 over the whole band. However, the pulse output has a badly distortion and the rise time of pulse signal is 31 ns. Because of the broadband of frequency of the circuit, parasitic parameters of diode are hard to estimated. Thus the model of detector diode is not so precise in the simulation. Other parameters may be involved in the fabrication of diode. More ways of analysis andsoftwares should be used in further study. And the fabrication work should be more preciser to improve the detection of circuits.