arXiv:2610.13560v1 Announce Type: new Abstract: High-frequency (HF) single-station localization estimates an emitter location from measured directions of arrival (DOAs) and an ionospheric propagation model. When the propagation mode composition cannot be identified from conventional direction-finding (DF) measurements, the same DF observation may produce multiple physically valid ground landing points under different propagation modes, making the location inversion ambiguous. This paper proposes a multimode time-frequency information fusion localization method (MTFIF-L).Rather than assuming a propagation mode a priori, MTFIF-L retains valid landing points generated under different propagation modes and uses repeated observations across time windows and, when available, multiple operating frequencies to progressively constrain the resulting candidate locations. Experiments on four measured HF links examine the respective roles of multimode candidate retention, cross-window processing, and cross-frequency processing. All four links yield unique location decisions. Links A--C achieve relative errors of $1.40\%$, $0.78\%$, and $3.41\%$, respectively.Link D, the only single-frequency case, also yields a unique decision from repeated temporal observations, although its post- localization error is substantially larger. Propagation-path analysis further reveals link-dependent differences in reflection layer, hop count, magnetoionic mode, and elevation angle among the ray-tracing paths associated with the measured links.Overall, the results show that repeated temporal observations can support localization within an individual frequency, while multifrequency information provides additional robustness against unreliable frequency-specific outcomes, enabling HF single-station localization under unknown and potentially coexisting propagation modes while retaining interpretable propagation information for post-localization analysis.