Since Global Navigation Satellite System (GNSS) signals were not designed for remote sensing, GNSS Reflection (GNSS-R) signals from the earth surface are so weak, especially for space borne GNSS-R receiver cases, which limits its application for earth surface remote sensing. To achieve stronger GNSS-R signals, this thesis analyzed the effect of GNSS Left-Hand Circularly Polarized (LHCP) antenna's central beam direction on the ocean reflected signals' SNR around Specular utilizing GREEPS simulator. It was found that the available maximum SNR and the corresponding incident angle was varied when the LHCP's central beam direction was different. The greatest maximum SNR was available when central beam direction's nadir off-pointing was 260 and the corresponding incident angle was 320 • The added SNR compared with the case with central beam direction's nadir off-pointing being 0°and the corresponding incident angle being 4° was more than 3 dB.