26-Meter Radio Telescopes

PARI Instruments

The Antenna

Both 26-meter radio telescopes point and track at sidereal or user-defined rates for astronomical observations. The control system was built by DFM Engineering, Inc. The 26m radio telescopes use position encoders with 18-bit resolution and the addition of dual 15 HP computer controlled synchro motors on each axis. PARI has conducted pointing model calibrations on the 26 East radio telescope to ensure pointing accuracy to within a quarter of a beamwidth at 2.3 GHz.

The receiver was built by a team led by Dr. Brian Dennison (UNC-Asheville). The team included Dr. David Moffett (Furman Univeristy) and more than a dozen undergraduate students over a five-year period. The description of the receiver provided here is by two UNCA students, John Goldthwaite and Jody Mann.

The Cartridge

Radio waves are captured by the cartridge feed which is a 27 inch (68.58 cm) diameter brass disk that has 10 constriction rings on its surface. The constriction rings act to narrow the frequency range received by the feed to the X and S bands. The feed is coupled to a wave guide that transfers the signal to S Band and X Band wave guides. A half wave splitter directs the right and left circular polarized signals into separate waveguides for the both S Band and X Band.

Each S Band waveguide has a signal pickup and a connection for injection of a calibration signal. The X Band waveguides terminate in an amplifier and have a connection for calibration signal injection. An integrated preamplifier and cab