With the application of active millimeter-wave holographic imaging as the background, the heterojunction AlGaAs/GaAs PIN diode millimeter-wave switch developed by the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences is a key core device in security imaging field. A compensation structure based on high and low impedance transform lines is proposed to optimize the matching degree at high frequencies. A millimeter-wave frequency doubling link, a low-insertion-loss bandpass filter, and a low insertion loss and high isolation switch channel array are designed to achieve a transmission front end that meets the requirements of the system with output power and consistency and good harmonic suppression. The results reveal that in the 28--34 GHz frequency band, the output power of each channel is more than 10 dBm, the harmonic suppression is more than 22 dBc, the channel isolation between channels is more than 23 dB, and the channel difference is less than 2 dB, all of which meet the requirements of active imaging transmitter. The imaging experiment can be performed after integrating the appropriate antenna array and the receiving front end, and the millimeter-wave imaging with a resolution of 0.5 cm can be acquired.