A new regional navigation satellite system that uses the L6 band to provide Positioning, Navigation, and Timing (PNT) services is being developed in Korea. However, in addition to the Radio Navigation Satellite Service (RNSS), the L6 band is shared with other services, leading to potential interference between services. Therefore, it is essential to analyze how interference signals in this band impact RNSS receivers. In this study, we investigated the radio frequency environment of the L6 band and experimentally analyzed the effects of interference signals on RNSS receiver performance. The results demonstrate that interference signals in the L6 band can significantly degrade the RNSS signal quality, adversely affecting both signal stability and positioning accuracy.