A Study on Compensation of Rain Attenuation with a Method of Aperture Synthesis Antenna in a Subtropical Zone

作为雨水衰减补偿的一种方法，我们利用干涉仪原理构造了由两个小孔径抛物面天线组成的孔径合成天线。用该孔径合成天线和其他单抛物面天线对广播卫星波进行了观测，并比较了衰减特性。首先，我们制作了一个普通的本地振荡器与一个Gunn二极管，产生一个10 GHz的信号。显示21 dBm输出功率和(]SY.+-。[)2 MHz/天的频率变化。我们重建了两个下变频器，以共同馈送来自外部的本地振荡器信号。孔径合成天线由两根偏置抛物面天线组成，其短直径为50 cm，基线长度为8 m，因为我们将孔径合成天线与另一观测一起使用。我们用于比较的其他单天线是两个偏移抛物面天线，短直径50厘米和75厘米，以及一个中心馈电抛物面天线，直径30厘米。与50 cm单天线相比，合成天线的雨衰减提高了1.1 dB。对功率合成器的匹配部分进行改进，使其性能更好。在三个单天线中，我们还比较了降雨强度大于10 mm/h时的降雨衰减特性。我们发现50 cm天线受雨水影响最大，75 cm、30 cm依次为。我们认为这是由天线波束方向和雨区大小造成的。所以我们建议继续进行详细的观察。如果可以的话，使用由更多小孔径天线组成的合成天线，例如直径30 cm的抛物面天线，有必要观察雨水衰减。

As a method of compensation of rain attenuation, we construct aperture synthesized antenna, which is applied a principle of an interferometer to, consisted of two small aperture parabolic antennas. We have observed Broadcast Satellite wave with that aperture synthesized antenna and other single parabolic antennas, and compared attenuation characteristics.First we made a common local oscillator with a Gunn diode which generates a 10 GHz signal. That shows 21 dBm output power and (]SY.+-。[)2 MHz/day frequency variation. We reconstructed two down converters to be commonly fed a local oscillator signal from the exterior.Aperture synthesized antenna is composed of two offset parabolic antennas, whose short diameter is 50 cm, and has 8 m baseline length because we use aperture synthesized antenna together another observation. Other single antennas which we use for comparison are two offset parabolic antennas, 50 cm short diameter and 75 cm, and one center feed parabolic antenna, 30 cm diameter.In comparison of 50 cm single antenna, the sythesis antenna improves rain attenuation by 1.1 dB.Improving matching section of power combiner, it will be made better.Also among three single antennas, we compare rain attenuation characteristics when rain intensity is over 10 mm/h. We find the 50 cm antenna is most influenced by rain, and in order 75 cm, 30 cm. We think that is caused by antenna beam pattern and rain area size. So we propose to continue an observation in detail. And if we can, using sythesized antenna which is composed of more small aperture antennas, for example 30 cm diameter parabolic antennas, it is necessary to observe rain attenuation.