Title:The Effect of Sea State on the Polarization of Reflected Beidou B1 Signals
VOLUME: 13 ISSUE: 5
Author(s):Tingting Lyu, Shuang Sha, Min Zhang, Hao Zhang* and Thomas A. Gulliver
Affiliation:Institution of Information Science and Engineering, Ocean University of China, Qingdao, 266100, China Open Studio for Marine High Frequency Communications, Pilot National Laboratory for Marine Science and Technology (Qingdao), Institution of Information Science and Engineering, Ocean University of China, Qingdao, 266100, China Open Studio for Marine High Frequency Communications, Pilot National Laboratory for Marine Science and Technology (Qingdao), Institution of Information Science and Engineering, Ocean University of China, Qingdao, 266100, China Open Studio for Marine High Frequency Communications, Pilot National Laboratory for Marine Science and Technology (Qingdao), Institution of Information Science and Engineering, Ocean University of China, Qingdao, 266100, China Open Studio for Marine High Frequency Communications, Pilot National Laboratory for Marine Science and Technology (Qingdao), Department of Electrical and Computer Engineering, University of Victoria, Victoria, V8P 5C2
Keywords:Beidou satellite navigation system, Rayleigh roughness criterion, reflected signal, polarization characteristics, polarization
diversity, douglas sea state.
Abstract:
Background: Oceanographic buoys generally employ satellites for positioning and data
transmission. However, sea surface conditions can affect these signals. The Signal to Noise Ratio
(SNR) of small observation buoys can be improved by exploiting polarization diversity.
Methods: This paper discusses the effect of sea surface conditions on the polarization and reflection
loss of Beidou B1 reflected signals for the purposes of exploiting polarization diversity. The
Rayleigh roughness criterion is used to assess the roughness of the sea surface. The Fresnel reflection
coefficients are derived to analyze the polarization and reflection loss of the Beidou B1 reflected
signals with different sea surface states.
Results: The results obtained show that for the Beidou B1 signals, the sea surface is considered
rough for most sea surface states and incident angles. For smooth sea surfaces, the Beidou B1 reflected
signals are mainly Left Hand Circularly Polarized (LHCP) waves, but Right Hand Circularly
Polarized (RHCP) waves dominate when the incident angles are larger than the Brewster angle.
The reflected loss is between -2 dB to -3.4 dB. In rough sea surfaces and the signals propagation is
dominated by diffuse reflection. The reflection loss decreases with the incident angle and there is a
fluctuation when the incident angle is around 49 degrees. The specular reflection signal has a significant
amplitude when the angle of incidence is large. RHCP waves are the main component of
the reflected signals, and the reflection loss is relatively small which can be employed for polarization
diversity or marine remote sensing.
Conclusion: polarization diversity is only useful with good sea conditions, and the corresponding
gain decreases with the deterioration of the sea surface conditions.
