Large antennas for ground-based astronomy above 1 THz

In its history astronomy has continuously expanded access to new wavelength regions both from space and on the ground. Today, one of the few unexplored regimes is the terahertz (THz) frequency range, more specifically above 1 THz (< lambda 300 mum). Astronomical observations above 1 THz are technically very challenging for a number of reasons including antenna technology, receivers, transparency of the atmosphere and calibration. Only recently, the very first observations at THz frequencies have been made with large antennas, and new observational facilities are planned. This contribution gives a brief overview of large THz antennas, one in operation (APEX), and two 25 m class antenna projects planned in Europe and the US