Vintage 30-m class telecommunications antennas built in the 1960s and 1970s have been converted into radio telescopes in recent years, with especially notable conversions in the United Kingdom, South Africa, Australia, Ghana, and most recently in Mexico. These antennas were designed and built for operation at C-Band, but in some cases the surface conditions are sufficiently good that observations at Ku-Band and possibly at K-Band may prove feasible. As described in [1] an antenna conversion project is underway for the Tulancingo-I telecommunications antenna, located in Tulancingo de Bravo in the Mexican state of Hidalgo. Although the antenna was in active use for several decades, it has been replaced by other communications technologies and has not been used since early in the new millennium. The antenna uses near-field, shaped Cassegrain optics, consisting of a shaped parabolic primary reflector and a shaped hyperbolic sub-reflector. The primary reflector is 32 meters in diameter with a nominal focal length of 9.6 meters. A tertiary reflector redirects the beam along the elevation axis, following the Nasmyth configuration. This paper describes our work to determine the feasibility of using the antenna reflector optics in the 18 – 24 GHz range of the K-Band. Both photogrammetry and laser tracker measurements were used to determine the geometrical relationship between the primary, sub-reflector, and tertiary surfaces. We use these results, reported in [4], along with computer simulations, to explore the potential of the Tulancingo-I antenna for KBand observing.
Sierra Negra (SN) is the site of the 50-m diameter Large Millimeter Telescope (LMT) at an elevation of 4600 m.a.s.l. located in the state of Puebla in central México. The LMT hosts several heterodyne and continuum instruments in the bands from 3 mm to 1 mm wavelength, thus making it necessary to have continuous opacity measurements at the millimeter wavelengths. The site has been monitored in the past using a commercial 225 GHz opacity radiometer. The 210 GHz Survey radiometer is an instrument previously used to search for the best Mexican site for the LMT. The Survey radiometer is a compact and portable instrument that has proven its reliability in remote sites. Due to its low cost and compact architecture the Survey radiometer has the potential to be reproduced and taken to other candidate radio astronomical sites in particular, locations for ngVLA antennas in northern México. In this paper we present the results of the measurements taken with the 225 GHz radiometer. The statistical data are consistent and within the dispersion measurements taken in the past. We also present a review of the Survey radiometer and recent data taken at the LMT site with this instrument. Furthermore, we compare current Survey data with data set taken by the 225 GHz radiometer at SN.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.