Wideband feeds and low noise amplifiers for large arrays

The state of the art for feeds and LNAs with frequency ranges approaching one decade will be presented. These components reduce the cost of receivers required to cover a given frequency range and enable observations requiring large bandwidth such as spectral index measurements, search for spectral lines with unknown red shift, and detection of transient events. An example of a 2 to 12 GHz feed will be given and compared in efficiency with an octave band feed. Low noise amplifiers for the 0.5 to 12 GHz range utilizing HEMT and SiGe bipolar transistor will be described.