Citation
Abstract
Sun experiments were performed to develop methods for accurately mapping the Sun noise temperatures over the entire solar disk at 32 GHz (Ka-band). Highresolution mapping of the Sun’s noise temperatures was obtained through the use of the 34-m beam-waveguide (BWG) antenna and the Ka-band monopulse receiving system at DSS 13. Detailed mapping of the solar disk was possible because at 32 GHz the BWG antenna has a full 3-dB beamwidth that is only 17 mdeg compared to the angular Sun diameter of about 0.5 deg. Due to the expected high noise temperature of the Sun (>10,000 K), methods had to be developed so that the incoming Sun noise-temperature power would not saturate the antenna receiving system. Of several methods investigated, only the absorber and waveguide attenuator methods were considered (1) to be easy and inexpensive to implement into any existing BWG receiving system and (2) to have the potential of giving accurate results. Both of these methods were used to measure the Sun noise temperatures presented in this article. Due to the high solar activity during the experiments, it was not possible to obtain repeatable results on difierent days and even on the same day. However, useful information has been obtained about the Sun’s noise-temperature characteristics during the period of maximum solar activity that occurred in the year 2000. To this author’s knowledge, this is the first time that a large (34-m) antenna was used to map the Sun’s noise-temperature profile over its entire surface at 32 GHz.
Keywords
Details
- Volume
- 42-145
- Published
- May 15, 2001
- Pages
- 1–32
- File Size
- 1.2 MB