The 42 foot CassHorn in development

The 42 foot CassHorn Prototype

Tom Minton, who worked for the Aero Geo Astro (AGA) Corporation, where the 42 foot CassHorn was developed, writes,

“This was the prototype made of a sandwich material that [we] worked on at Taylor’s Island MD when I was with the Aero Geo Astro (AGA) Corporation in Alexandria VA. This had the very simple feed used for efficiency and noise temperature testing. [It] was well before Page deployed the metal skinned versions with the much more complex circularly polarized, monopulse tracking feeds, one of which went to Carnarvon.

I’ve also attached to original CassHorn design paper. It was known then as the KSK antenna after one of its designers Kenneth S. Kelleher (president of AGA); Stan Jones, the co-author works at the same company I do today (the MITRE Corporation).

I submit that the design paper deserves to be included on the website with the Carnarvon OTC (A) material. Please consider it as a valuable piece of engineering history.” (November 2016)

Stan Jones adds,

“Tom may not remember this, but the design may not have survived its birth.

I was on vacation when the first prototype was assembled. Test range radiation patterns were made shortly after I came back and they were awful. After the initial panic, we discovered they had assembled the parabolic segment of the reflector upside down. When this was corrected, we got the patterns shown in the paper Tom sent.

Good to know that optical theory works.” (November 2016.)

Design paper: “A New Low Noise, High Gain Antenna”, by Stanley R. Jones and Kenneth S. Kelleher, 1963. Click the image to open a 930kb PDF file. Scan courtesy of Tom Minton. The abstract reads: “A new antenna type is described which combines the low noise temperature characteristics of the horn-reflector antenna with the more attractive mechanical features associated with the paraboloidal reflector. Cassegrain optics used in an off-set feed configuration enables a virtual source to be formed without sub-reflector blockage. An extremely compact structure is realized with a concave hyper-boloid which mirrors the actual feed located on the paraboloidal surface. Except for the aperture, the antenna is completely shielded. The design approach is outlined and measurements on an experimental model are presented. Ground noise contribution from minor lobes is about 2°K.”

A prototype of the CassHorn design, being evaluated at Taylor’s Island, Maryland, by the Aero Geo Astro Corporation. Photo: Tom Minton.

A prototype of the CassHorn design, being evaluated at Taylor’s Island, Maryland, by the Aero Geo Astro Corporation. Photo: Tom Minton.

A prototype of the CassHorn design, being evaluated at Taylor’s Island, Maryland, by the Aero Geo Astro Corporation. Photo: Tom Minton.

A prototype of the CassHorn design, being evaluated at Taylor’s Island, Maryland, by the Aero Geo Astro Corporation. Photo: Tom Minton.