Design of W-band Front End for Active Imaging System

As the key component which influence the performance of active imaging system, the front end should be comprehensively considered of its frequency, band width, output power, size and cost. In this paper, we utilize frequency conversion method to implement a low-cost W-band frontend for active imaging system. First, based on the theory of millimeter-wave frequency multiplication, frequency mixing and the precise modeling of planer Schottky barrier diode (SBD), we use co-simulation technique and adopt alumina ceramics substrate to implement a W-band frequency tripler and a sub-harmonic mixer. The tripler uses anti-parallel diode pair (APDP) as a no-linear device to form a balanced structure, and its harmonic suppression degree can reach more than 40 dBc. The sub-harmonic mixer is a single-balance structure of branch type, achieving 9 dB conversion loss from 88 ~ 104 GHz. The above devices are low cost and small dimension, and exhibit excellent in a millimeter-wave nondestructive evaluation system.