A novel frequency synthesis method for fast frequency hopping in the Ka band is proposed, which achieves frequency spectrum shifting of low-frequency signals through multi-level mixing. A miniaturized, low-power, and simple frequency implementation method is also proposed. This method can achieve fast frequency hopping and incorporates an implementation method of in-loop mixing on the basis of the original design method, which can greatly reduce the N-division ratio of the Phase-Locked Loop (PLL) and improve the phase noise of the output signal. The improved frequency synthesis method compensates for the shortcomings of the original frequency synthesis method and can be extended and applied to multiple types of communication and radar systems. After engineering verification, the new Ka band agile frequency synthesis technology has achieved significant results and can solve practical problems that hinder the engineering application of direct frequency synthesis technology. It is a new Ka band agile frequency synthesis technology that can be promoted and applied.