LNF to deliver cryogenic Low Noise Active Baluns to SETI

Onsala, Oct 2005

LNF signs a contract with the SETI Institute to deliver cryogenic Low Noise Active Baluns f$ Allen Telescope Array (ATA).
ATA utilizes a novel log-periodic feed that covers the entire frequency range of 0.5-11 GHz instantaneously. The feed output is balanced and therefore an amplifier with a balanced input is required. To allow the usage of simple coaxial transmission lines on the output, the LNA has an unbalanced output. In other words, the LNA acts as both a balun and an amplifier, hence the name, active balun.

ATA will eventually consist of 350 six meter antennas with dual polarization feeds and therefore the number of Active Baluns required is 2*350=700. Building hybrid circuits in such large quantities is very costly and therefore a MMIC using 0.1 µm InP HEMTs was developed. This development was done at California Institute of Technology by LNF associates.


Photograph of the active balun module with the cover removed


Measured gain and noise temperature cooled down to 12K, showing Tn<8K from 0.5-11 GHz.