The New Arecibo HF Interactions Facility Dual Array Cassegrain Antenna Design

Open Access
Author:
Labowski, Kyle L
Graduate Program:
Electrical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 06, 2009
Committee Members:
  • James Kenneth Breakall, Thesis Advisor
  • Lynn A Carpenter, Thesis Advisor
Keywords:
  • FEKO
  • Arecibo
  • HF Interactions
  • Antenna
Abstract:
A new HF facility at Arecibo will replace prior facilities that are no longer in operation. The location of the observatory at Arecibo is perfect for HF studies. It will provide the ability to study the upper atmosphere, study plasmas, and several other uses. The facility will make use of the infrastructure already in place at the Arecibo Observatory. One of two arrays of cross dipoles, operating at 5.1 MHz or 8.175 MHz respectively, will project energy onto a mesh net with 5 foot openings. The energy will then reflect back onto the 305 m diameter dish already in place at Arecibo. Together they will form a cassegrain system for the HF facility. The arrays will be either RHC or LHC polarized. A combination of GNEC and FEKO was used to model and analyze this design. The design was examined for VSWR, gain, cross polarization rejection, and near field effects. The final design is predicted to have less then 2:1 VSWR across a 100 kHz band at each center frequency. The predicted gains are 22.16 dBi at 5.1 MHz and 25.46 dBi at 8.175 MHz. The antennas will be fed with six, 100 kW sources for a total of 600 kW. This corresponds to an ERP of 98.6 MW at 5.1 MHz and 210.9 MW at 8.175 MHz. There will be no danger to visitors to the facility due to field levels. It is, however, recommended that workers at the facility do not stay on the platform while the facility is in use.