@proceedings {488, title = {History of Antenna Technology at the Arecibo Observatory, Arecibo Puerto Rico}, year = {2021}, month = {03/2021}, publisher = {HamSCI}, address = {Scranton, PA (Virtual)}, abstract = {

The Arecibo Observatory first opened in 1963 and has been a marvel in engineering ever since. It has been a monumental instrument for scientific research in the fields of astronomy, planetary radar, ionospheric probing and HF heating modification, and optical probing of the atmosphere. While the science and the discoveries are well known to many, the antenna technology and engineering are equally as impressive as the discoveries. The original concept, by Prof. William Gordon in the Electrical Engineering Department at Cornell University, was for a 1000 foot parabolic dish aiming only at zenith, with no tracking capability for studies of the ionosphere with the newly developed technique of incoherent scatter radar (ISR). Fortunately, knowledge of some on going research with spherical reflectors was suggested where the feed could be moved to slew the beam. The rest is history that will be the described in this talk up to the collapse. Most of the 430 MHz 96 foot line feed broke off and fell through the dish in 2017 during Hurricane Maria. Then in December 2020, the platform fell into the dish destroying large sections of the dish and the equipment in the platform.\ There is so much more to tell about the engineering at Arecibo that will be the subject of this presentation at HamSCI 2021.\ 

}, url = {https://hamsci2021-uscranton.ipostersessions.com/?s=C9-8F-A9-0F-A8-29-2C-C5-63-16-4B-2E-E7-47-F7-0A}, author = {James K. Breakall} } @conference {297, title = {The New Arecibo Ionospheric Modification HF Facility Dual Array Cassegrain Antenna {\textendash} History and Design}, booktitle = {HamSCI Workshop 2019}, year = {2019}, month = {03/2019}, abstract = {

A new HF facility has been built at Arecibo Observatory, Puerto Rico, that has replaced the prior Islote heater that was destroyed by Hurricane Georges in 1998. It was decided to use the 1000 foot dish for this new heater antenna instead of rebuilding the previous installation. This will make it possible to have all research activities with ionospheric modification including the 430 MHz incoherent scatter radar (ISR) to be located at the Observatory. This will be perfect to provide the ability to study the upper atmosphere, study plasma effects, and other future experiments. Historically, ionospheric modification has been carried out before at Arecibo using originally a Yagi and later a crossed-log periodic antenna hanging from the platform. These both had logistic and electrical arcing problems, and that was what led to the construction of the Islote facility on the north coast of Puerto Rico. The Islote facility also had logistic and arcing problems from both the wires in the antenna and the wire cage pseudo-coaxial transmission lines. The transmission lines were upgraded, and this improved performance and reliability greatly just before the hurricane destroyed the facility. The first feasible concept to be considered for the current design was a dual-band crossed-Yagi that would hang with cables from pulleys and winches on the three support towers. The total power for each polarization would then travel up a 4-wire open transmission line from below. A combining and phasing system design was formulated for the six 100 kilowatt transmitters in this concept. It was later decided to use another design based on a Cassegrain concept of a phased-array at the bottom of the dish feeding energy to a sub-reflector mesh hanging from cables and winches from the three support towers. This paper will describe some of the history and the design of the present antenna that is currently being used for ionospheric modification at Arecibo.

}, author = {James K. Breakall} }