Investigating Dual-Frequency HPM Interference Effect on Communication System: Insights From LNA to SDR

In this paper, we investigate the impact of dual-frequency high-power microwave sources on communication systems. We begin by analyzing the nonlinear characteristics of the system using a fifth-order power series expansion. Subsequently, we examine the nonlinear behavior of the low-noise amplifier (LNA) under dual-frequency high-power microwave exposure. Besides gain compression, the exposure generates intermodulation signals, which are the primary source of communication interference. This effect is validated on a general communication system utilizing QPSK modulation with a software-defined radio (SDR) platform, with error vector magnitude (EVM) employed as the performance indicator. Our results demonstrate that when the intermodulation signal produced by dual-source interference aligns with the communication frequency, it is the dominant source of interference, overshadowing the blocking effect of the large signal. The precise impact of the interference depends on the configuration of the two power sources.