Research On Miniaturized Microwave Broadband Delay Line Technology

In recent years,the technology of wideband phased array radar has developed rapidly,and it has gradually entered the stage of actual combat.Due to the shortcomings of phase shifters,the phased array system can not overcome the limitation of aperture effect.When the instantaneous large broadband signal is used,the spatial dispersion of the beam will happen,that is,the deviation of the beam pointing.The way to solve this problem is to use the delay line to cancel the aperture transit time at the array or sub array level,so as to achieve the undistorted reception or transmission of the signal under the instantaneous large broadband signal.The miniaturization and broadband development of radar system require delay line with high accuracy,high linearity and low loss.At the same time,it should also meet miniaturization,broadband and light weight.The delay line using radio frequency multilayer technology can not only realize the miniaturization design with the threedimensional structure,but also make the delay line transmit in the form of no dispersive strip line,which improves the performance of the delay line.In this paper,the characteristics of RF multilayer printed board technology are described first,and then the factors that affect the vertical transition structure of the ribbon line,the coupling of the ribbon line and the grounding isolation hole are analyzed.The matching modeling and analysis of the gold wire bonding are also carried out to improve the transmission property caused by the gold wire bonding.Then,a low-frequency UWB delay cell based on RF multilayer board technology is designed and tested in order to verify the accuracy of the model and the error caused by the processing.The final test results: working frequency 2GHz ~ 6GHz,the straight branch standing wave is less than 1.4,the insertion loss is-1.8dB ~-2.5dB,loss fluctuation is less than or equal to 0.7dB,the delay branch of standing wave is less than 1.42,the insertion loss is-3dB ~-5dB,loss fluctuation is less than or equal to 2dB,the entire band phase linearity less than 6.5 degrees,the volume is 33 mm * 34 mm * 6mm.On the basis of the above work a 5 bit delay amplifier module for X band is designed.The operating frequency band is 8GHz to 12 GHz,which is composed of four same delay amplification channels,the delay amplification channel signal is output from the back end after the power divider,each delay amplification channel selects the receiving link or the transmit link by the transceiver switch,and the receiving link in the channel shares the delay line part with the transmission link.5 delay units produce 0.5 ?,1 ?,2 ?,4?,8 ? respectively,after cascade,the step is 0.5 ?,and the total delay is 15.5 ?.The transmission channel also adopts the form of multi laminate,which fully embodies the advantages of the three-dimensional structure of the multilayer board,and greatly reduces the size of the components.The final test results of single channel: the gain of the receiving link is between 15.6dB and 17.4dB,the flatness is lower than 2dB,the phase linearity is lower than 10 degrees,the transmission link gain is between 30.8d B to 34.6dB,the flatness is lower than 4dB,and the phase linearity is lower than 14 degrees,the volume is 166 mm * 40 mm * 20 mm.