Study On Automatic Test Technology Of Electromagnetic Parameters Distribution Of Rod Used For Traveling Wave Tube

Whether in the field of radar?communications or electronic countermeasures,spiral travelling-wave tubes are widely used due to their wide frequency band,high efficiency,and high power.As an integral part of the spiral traveling wave tube,it is very important for the holding rod to measure its electrical parameters.According to actual needs,the test of the electric parameters of the holding rod in travelling-wave tubes is mainly divided into two parts,one is the test of the complex permittivity of the clamp rod;the other is the test of the attenuat ion distribution of the attenuation coating of the clamp rod.In order to test the complex permittivity of the clamping rod,two perturbation resonators of different sizes were designed to satisfy the test of the complex permittivity of the clamping rods in the two sets of bandwidths of C^Ku band and K^Ka band,respectively.The perturbation resonators are based on the TM_0n0n0 mode as the test mode.In order to purify the interference mode,several narrow gaps,with the absorbing material,are set on the bottom surface of the cavity,while microwave signals are coupled into the cylindrical cavity through the rectangular hole.At the same time,two different test sensors are designed to test the attenuation distribution rule of the attenuating coated holding rod at different frequency bands.The test sensor adopts a tapered transmission line model of complex function to transform the standard rectangular waveguide to 1 mm thick flat waveguide,and a hole is designed on the center of the flat waveguide.During the test,field leakage is caused by the coating on the holding rod,there is a shielding device designed to ensure the accuracy of the test.In addition,in order to realize the automatic test,a dialog-based automated test software was written by using VC++.The test software mainly includes three modules:motor control,vector network test and data processing,which achieves the extraction and recording of test data,the initialized position of the holding rod and the stepping forward of motor.These operations greatly reduce the amount of operators'test work,allowing the test to be performed quickly.