Research On Key Techniques Of W Band Radar Front End

In recent years,with the rapid development of military and civilian wireless communication technology,millimeter wave has been universally used in radar and guidance,electronic confrontion,communication,remote sensing detection,imaging and other systems.The radar front-end plays a key role in the millimeter-wave radar system,whose performance needs to be further improved while there are a large number of research and papers on it in the domestic.Therefore,this thesis focuses on the key techniques of the W-band radar front end-single pole double throw(SPDT)switch,high-gain amplifier,a W-band direct detection narrowband radiometer front-end and W-band broadband dual-channel radiometer front-end.Specific research contents are as follow:In this thesis,the receive and transmit are controlled by the SPDT switch in the radar front-end.Based on the theoretical analysis of the W band SPDT switch,the impedence matching is successfully designed after the extraction of PIN diode parameters.Since the input and output of the SPDT switch are standard rectangular waveguide,the transition structure of a W-band waveguide-to-coplanar waveguide and a W-band waveguide-to-microstrip line are designed.Finally,the measurement results show that the insertion loss is less than 2dB,the isolation is more than 15 dB and the switching time is less than 30 ns in the range of 90-93.5GHz.Based on the traditional single low noise amplifier(LNA)chip design,the W-band high gain amplifier is designed by cascade structure of two LNA chips.The measure-ment results show that the gain of the W-band high gain amplifier is greater than 40 dB in the range of 95-97 GHz.The W-band direct detection narrowband radiometer front-end is designed based on the high-gain amplifier above.In the design of the narrowband radiometer front-end,the bandpass filter is designed to achieve the effect of frequency selection.Meanwhile,the front-end signal uses differential output after the detection amplifier circuit.At the bandwitch of 2GHz and the transient time of 1ms,the temperature sensitivity of the radiometer front-end is less than 1K and temperature drift rate is 0.83 K/?.Finally,the W-band broadband dual-channel radiometer front-end and the W-band miniaturized broadband dual-channel radiometer front-end for the imaging system are designed on the basis of the previous work about W-band single-channel radiometer front-end.Ten W-band broadband double-channel radiometer front-ends are designed whose temperature sensitivity is lower than 0.4K at the transient time of 1ms with the temperature drift rate of 2.7 K/?.Meanwhile,twelve W-band miniaturized broadband double-channel radiometer front ends are manufactured.At the integration time of 1ms,the measured results show that the temperature sensitivity of each module achieves 0.4K.The front-ends have been successfully applied in an imaging system that can conduct effective detection of hidden metal and non-metallic objects carried by people.