This effect became known as "squint" and was generally considered annoying, especially on the AMES Type 80 where servicing the magnetron required a lengthy recalibration process to bring the beam back in line with the antenna.
This leads to the possibility of radar that can scan its beam in a chosen direction, typically vertically, with no moving parts.
This presented a potential issue in a radar using squint scanning, which would presumably send the signals in different directions if pulse compression were used.
It appeared that as long as the beam steering was at the right speed it would be possible to do both; a given target would only see a small change in frequency as the beam scanned passed it, but the signal would dwell on any one target long enough that there would be a notable frequency shift during the resulting reflection that could be used for pulse compression.
The system was modified and testing resumed in 1968 with the result that the detection range had improved but the height finding accuracy was lower than desired.
[3] Plessey felt the basic concept still offered significant benefits, at least in less-demanding roles, and that it could be greatly improved by increasing the bandwidth past what was possible with its original 1960s-era systems.
In 1973 they received Ministry of Defence (MoD) funding to build an example set with a potential 150 MHz bandwidth, which was operational the next year.
[3] The ideal market would be day-to-day traffic control around a military airport, where the secondary function of early warning would still be useful.
[4] According to Burr, the countries were assigned code names, with Penguin referring to the UK Ministry of Defence, and Rodent, Condor, Lion and Falcon to outside-UK sales.
[8] Newspaper reports from 1986 state another six were sold to Iran, but it is not clear if this is included in the list above or represents new-build systems.
Seeking a way to apply their work on the AR-3D to a new frequency agile radar, Plessey entered an agreement with ITT-Gilfillan of Los Angeles.
The lowest elevation "beams" also had moving target indication clutter suppression to eliminate ground returns.
[4] The output of the receivers was then sent to a plot extractor, which identified moving objects in the returns and attempted to automatically assign tracking information - direction and speed.