Search

A short-backfire antenna (SBA) with corrugated structure on the aperture edge of the main reflector is designed to suppress sidelobe and enhance the isolation. The corrugated SBA is suitable for closed-pack antenna array. Early prototype antenna measured results indicate that the radiation pattern is well fit to the design and simulation. The simulation also indicates that the spill over temperature is below 11K over 700- 900MHz if the SBA is integrated to the 100-meter Green Bank Telescope. more...

The Atacama Large Millimeter/submillimeter Array(ALMA) Band 1 receiver covers the 35-50 GHz frequency band. Development of prototype receivers, including the key components and subsystems has been completed and two sets of prototype receivers were fully tested. We will provide an overview of the ALMA Band 1 science goals, and its requirements and design for use on the ALMA. The receiver development status will also be discussed and the infrastructure, integration, evaluation of fully-assembled band 1 receiver system will be covered. Finally, a discussion of the technical and management challenges encountered will be presented. more...

The prototype cartridges for ALMA Band-1 receivers have been developed, based on the key components developed in ALMA Band-1 consortium laboratories. The prototype cartridges for each receiver consist of two parts, cold cartridge assembly and warm cartridge assembly. The cold cartridge assembly (CCA) consists of horn antenna, orthomode transducer and a pair of 35-52 GHz cold low-noise amplifiers, the amplified signals of both polarizations are transmitted to warm cartridge assembly by long waveguide sections. In warm cartridge assembly (WCA), two major modules incorporated, down-converter assembly including warm low-noise amplifier, high-pass filter, mixer and 4-12 GHz IF amplifier, and local oscillator based on a 31-40 GHz YIG-tunes oscillator. The frequency range is based on the upper sideband scheme. Based on the measured performance of the key components, the expected noise performance of the receiver will be 26-33K. more...

The Band-1 receiver front-end cartridges for Atacama Large Millimeter Array, which covered 35–50 GHz frequency range, are now in preproduction stage. For the first three preproduction cartridges, the measured receiver noise temperature is less than 16–31K for any combination of the inband RF and LO frequencies. The measured gain flatness, even with the limitation of the optical window of the cryostat and the broadband matching of the cryogenic amplifiers, is typically lower than 5 dB over any 2GHz window. Extracted aperture beam efficiency is typically higher than 80% over the full frequency range. The crosstalk over the orthogonal channel is lower than −63 dB. For the suppression of the unwanted lower sideband, the imaged band suppression is higher than 20 dB for the worst case and around 30 dB typically. more...