| Description: | Feeds and low noise amplifiers with decade bandwidth are being developed for radio astronomy, particularly for large arrays, such as SKA. The rationale is fewer receivers to cover a given frequency band and simultaneous observations of the objects spectra (many spectral lines, pulsar dispersion, and continuum spectral index) with a small loss in antenna efficiency and system noise. Feeds and cooled LNA's for the 0.5 to 10 GHz range will be described and system integration issues will be discussed. Data will be presented concerning the minimum noise temperature of several manufactures of SiGe transistors and the performance will be compared with InP HEMT transistors. |
