Accurate Angle of Arrival (AoA) estimation is essential
for channel characterization and localization in 5G and
6G systems, where directionality and multipath propagation play
a dominant role. This paper presents a Zero-Crossing Path
Difference of Arrival (PDoA) method that retrieves AoA directly
from measured S-parameters using a minimal two-antenna array.
The technique exploits the zero-crossing of the propagation
path difference between receiver elements as the array rotates,
enabling unambiguous AoA detection with full 360° coverage.
Unlike conventional phase-difference or interferometric methods,
the proposed approach avoids phase ambiguity and does not
require large antenna arrays. The method is implemented and
validated through wideband frequency-domain measurements in
anechoic chamber and outdoor scenario, showing AoA errors
as low as 0.2° indoors and below 4° in outdoor comparisons
with ray-tracing simulations. The results demonstrate that the
Zero-Crossing PDoA method offers a simple, accurate, and
computationally efficient solution for practical AoA measurement
and channel characterization for the next-generation wireless
systems.