The 42 foot Cassegrain horn antenna
(also known as the TT&C antenna)

The first OTC Earth Station antenna was a fully steerable 42 foot aperture cassegrain-fed folded-horn antenna, with interacting parabolic and hyperbolic reflectors.

It was built by the Rohr Corporation of California – who were well known in building similar structures (they won the contract to build the 64m Mars dish at Goldstone).

The first – though unscheduled – assignment for the antenna was to test links to the UK through Intelsat-2A on 29 October 1966. Three weeks later, when the satellite was again in a favourable position, it was used for the Down Under Comes Up Live broadcast.

The antenna began communicating through the Pacific-1 (Intelsat-2B) on 11th January 1967 – three weeks after that satellite’s launch. Three weeks later, in February 1967, it commenced its role as satellite relay station in support of the NASA MSFN Carnarvon Tracking Station.

Jim Harte has shared these photos of the construction –

Assembly of the 42 foot cassegrain horn begins. Photo: Jim Harte.

The 42 foot cassegrain horn begins to take shape. Photo: Jim Harte.

The ungainly looking 42 foot cassegrain horn and associated support vans. Photo: Jim Harte.

The 42 foot cassegrain horn. Photo: John Lambie.

The completed 42 foot cassegrain horn. Photo: OTC. Scan: Colin Mackellar.

The 42 foot cassegrain horn. The crane in the background may be the beginning of work on the 97 foot parabolic antenna. Photo: John Lambie.

The OTC Carnarvon Casshorn antenna is the last remaining example of this design of antenna anywhere in the world.