Antenna is one of the key payloads of the GNSS-R system, and the gain is an important performance parameter. The signal-to-noise ratio (SNR) of the received signal can be improved by increasing the gain of the GNSS-R antenna, therefore the measurement accuracy is improved. However, the antenna gain and its beam width, these two performance parameters, are contradictory. If the gain of the antenna is increased, its beam width will inevitably become narrower. This narrowed beam width will affect the width of the survey strip for the GNSS-R system, which cannot meet the requirement of the high-precision and high-spatial resolution spaceborne GNSS-R sea surface altimetry in the future. In this paper, a novel dual circularly polarized phased array antenna (NDCPPA) is proposed and investigated. First, the GNSS-R satellites currently operating in orbit are all cGNSS-R systems, which use the traditional element antenna (TEA) method for measurement. The antenna used in this method is with low gain, which limits the improvement of sea surface measurement accuracy. In response to this problem, this paper establishes an NDCPPA model of iGNSS-R measurement system based on the theory of coherent signal processing on the sea surface. This model uses the high-gain scanning beam to increase the gain of the iGNSS-R antenna without affecting its coverage area, thereby improving the sea surface altimetry precision. Second, in order to verify the gain improvement effect brought by adopting the NDCPPA model, an NDCPPA model verification prototype for iGNSS-R sea surface altimetry was designed and fabricated, and then measured in a microwave anechoic chamber. The measurement results show that, compared with the TEA method, the antenna gain of our proposed verification prototype is enhanced by 9.5 dB. And the measured and designed value of the gain of the verification prototype matches well. Third, based on the GPS L1 signal, the NDCPPA model is used to analyze the effect of improving the precision of sea surface altimetry. Compared with the TEA method, the proposed model can increase the altimetric precision of the nadir point from 7.27 m to 0.21 m, which effectively improves the performance of the iGNSS-R altimetry. The NDCPPA model proposed in this article can provide the theoretical method basis and the crucial technical support for the future high-precision and high-spatial-resolution GNSS-R sea surface altimetry verification satellite.

中文翻译：

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基于新型双圆极化相控阵天线模型提高GNSS-R海面测高精度

天线是GNSS-R系统的关键有效载荷之一，增益是一个重要的性能参数。增加GNSS-R天线的增益可以提高接收信号的信噪比(SNR)，从而提高测量精度。但是，天线增益和波束宽度这两个性能参数是矛盾的。如果天线的增益增加，其波束宽度必然会变窄。这种窄波束宽度将影响GNSS-R系统测绘带的宽度，无法满足未来高精度、高空间分辨率的星载GNSS-R海面测高要求。在本文中，提出并研究了一种新型双圆极化相控阵天线（NDCPPA）。第一的，目前在轨运行的GNSS-R卫星都是cGNSS-R系统，采用传统的元件天线（TEA）方法进行测量。该方法使用的天线增益较低，限制了海面测量精度的提高。针对这一问题，本文基于海面相干信号处理理论，建立了iGNSS-R测量系统的NDCPPA模型。该模型利用高增益扫描波束，在不影响覆盖范围的情况下提高iGNSS-R天线的增益，从而提高海面测高精度。其次，为了验证采用NDCPPA模型带来的增益提升效果，设计制作了iGNSS-R海面测高的NDCPPA模型验证样机，并在微波消声室中进行测量。测量结果表明，与TEA方法相比，我们提出的验证原型的天线增益提高了9.5 dB。且验证样机增益的实测值与设计值匹配良好。第三，基于GPS L1信号，利用NDCPPA模型分析提高海面测高精度的效果。与TEA方法相比，该模型可以将天底点的测高精度从7.27 m提高到0.21 m，有效提高了iGNSS-R测高的性能。本文提出的NDCPPA模型可为未来高精度、高空间分辨率GNSS-R海面测高验证卫星提供理论方法基础和关键技术支撑。我们提出的验证原型的天线增益提高了 9.5 dB。且验证样机增益的实测值与设计值匹配良好。第三，基于GPS L1信号，利用NDCPPA模型分析提高海面测高精度的效果。与TEA方法相比，该模型可以将天底点的测高精度从7.27 m提高到0.21 m，有效提高了iGNSS-R测高的性能。本文提出的NDCPPA模型可为未来高精度、高空间分辨率GNSS-R海面测高验证卫星提供理论方法基础和关键技术支撑。我们提出的验证原型的天线增益提高了 9.5 dB。且验证样机增益的实测值与设计值匹配良好。第三，基于GPS L1信号，利用NDCPPA模型分析提高海面测高精度的效果。与TEA方法相比，该模型可以将天底点的测高精度从7.27 m提高到0.21 m，有效提高了iGNSS-R测高的性能。本文提出的NDCPPA模型可为未来高精度、高空间分辨率GNSS-R海面测高验证卫星提供理论方法基础和关键技术支撑。且验证样机增益的实测值与设计值匹配良好。第三，基于GPS L1信号，利用NDCPPA模型分析提高海面测高精度的效果。与TEA方法相比，该模型可以将天底点的测高精度从7.27 m提高到0.21 m，有效提高了iGNSS-R测高的性能。本文提出的NDCPPA模型可为未来高精度、高空间分辨率GNSS-R海面测高验证卫星提供理论方法基础和关键技术支撑。且验证样机增益的实测值与设计值匹配良好。第三，基于GPS L1信号，利用NDCPPA模型分析提高海面测高精度的效果。与TEA方法相比，该模型可以将天底点的测高精度从7.27 m提高到0.21 m，有效提高了iGNSS-R测高的性能。本文提出的NDCPPA模型可为未来高精度、高空间分辨率GNSS-R海面测高验证卫星提供理论方法基础和关键技术支撑。与TEA方法相比，该模型可以将天底点的测高精度从7.27 m提高到0.21 m，有效提高了iGNSS-R测高的性能。本文提出的NDCPPA模型可为未来高精度、高空间分辨率GNSS-R海面测高验证卫星提供理论方法基础和关键技术支撑。与TEA方法相比，该模型可以将天底点的测高精度从7.27 m提高到0.21 m，有效提高了iGNSS-R测高的性能。本文提出的NDCPPA模型可为未来高精度、高空间分辨率GNSS-R海面测高验证卫星提供理论方法基础和关键技术支撑。