This paper introduces an innovative Interpolation-based Radar Simulation System (IRSS) designed to simulate Doppler frequencies across multiple frequencies with minimal hardware complexity. Traditional radar simulation systems, such as Analog Radar System Simulators (ARSS) and Digital Radar System Simulators (DRSS), face challenges when supporting multi-frequency simulations due to the need for parallel processing of individual Doppler frequencies. The proposed IRSS exploits linear interpolation and superposition property, enabling a single interpolation process to handle multiple frequency components efficiently. The IRSS structure was implemented using an FPGA-based USRP, and its performance was evaluated through experim-ental testing. The results demonstrated that the IRSS accurately generated Doppler frequencies for both single and multi-frequency signals, maintaining consistency with theoretical predictions. The system effectively simulated Doppler shifts for various target speeds while preserving hardware simplicity, unlike traditional simulators that require increased resources proportional to the number of frequencies. This research highlights the advantages of using linear interpolation to reduce hardware complexity and improve scalability in radar simulators. Consequently, the proposed IRSS provides a cost-effective and efficient solution for modern radar systems that demand multi-frequency capabilities, making it well-suited for applications in complex environments such as autonomous vehicles, military operations, and aviation.