Semi‐active laser/millimetre wave beam combiner design and test

The semi-active laser /millimetre wave (MMW) beam combiner design methods including the MMW transmission structure design method and laser diffuse surface design method were proposed. The transmission line theory was adopted to design the MMW transmission structure. The Lambert's law assumption was adopted when the diffuse reflection surface of the beam combiner was designed. In the aim of illustrating the design methods, a thin plate beam combiner design case was given to meet the performance requirements which were proposed according to the test requirements of the unit under test. In order to validate the MMW transmission structure design method, a prototype made of polytetrafluoroethylene was fabricated and it was tested in a Ka band compact range anechoic chamber. In order to evaluate the laser reflection performance, the laser reflection performance at a wavelength of 1.064 μm was also tested and analysed by an empirical bidirectional reflectance distribution function model.