The VERLORT radar at Muchea:Photo - ???
The VERLORT radar at Muchea:
Photo - ???

The VERy LOng Range Tracking (VERLORT) S-band radar (2700 t0 2900 MHz) was an extended-range version of the SCR-584 - often credited as "the radar that won WW II".

For space missions, its range was increased from 650 Km to 4000 Km; the dish diameter from 1.8 m to 3 m and it was given a long name befitting its new space-tracking capabilities. The Red Lake (Woomera) Mercury tracking station used the more accurate AN/FPS-16 radar installed at Woomera for previous space activities.

The VERLORT radar reinstalled at Carnarvon just beside the AcqAid antennas:Photo - Alan Gilham
The VERLORT radar reinstalled at Carnarvon just beside the AcqAid antennas:
Photo - Alan Gilham

The Verlort performed reliably for the six Mercury orbital missions at Muchea. It was then relocated to the new Gemini tracking station at Carnarvon as an acquisition aid and back-up for the even more accurate FPQ-6 radar to be installed there.

Although the Verlort was kept operational at Carnarvon for the first few missions it was soon taken off the operational list once the FPQ-6 proved its reliability and other acquisition methods also proved sufficient.

Some innovative mechanical solutions

Helical scan mechanism:Image – ‘Electronics’; Fig 2, Dec ’45, p.104
Helical scan mechanism:
Image – ‘Electronics’; Fig 2, Dec ’45, p.104

The SCR radars, developed at the MIT laboratories, were remarkable for MIT’s innovative mechanical solutions to radar operations that are now met by electronic methods in modern radars.

The Verlort Plan Position Indicator (PPI) was driven by a mechanical computer. Once target acquisition occurred, the radar operator needed to keep a ‘hairline’ indicator manually centred on the target’s echo to maintain track.

Even more intriguing were the target acquisition techniques.

For targets where only crude position information was available, a helical scan was used to acquire the target. The dish was swung in a circle at 6 rpm along as it moved with the reflector tilting to and fro about 4° per dish revolution to create a helical spiral about 20° wide along the expected track path - see 'Helical scan mechanism' diagram on right.

Where there was more certainty about the target path, a nutating scan mode was used. The slightly offset dipole feed was rotated rapidly to produce off-axis radiation increasing the effective beam width from 2.5° to about 5.5° . Nutation was switched off when the target was acquired. See the ‘conical scan beam’ diagram below left and the ‘nutating antenna dipole feed’ below right.

A conical scan beam: Image – ‘Electronics’; Fig 1, Nov ’45, p.104
A conical scan beam:
Image – ‘Electronics’; Fig 1, Nov ’45, p.104
Nutating antenna dipole feed:Image – ‘Electronics’; Fig 5, Dec ’45, p.107
Nutating antenna dipole feed:
Image – ‘Electronics’; Fig 5, Dec ’45, p.107

For a detailed technical description of the SCR-584 radar see the November & December 1945 issues of ‘Electronics’ magazine at

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