PRIMARY RADAR
Primary Radar – it is used to determine the range of the A/c & bearing with respect to the station. It does not require any special equipment to be carried on board the A/c, except the VHF Radio Telephony set.
Operation– A continuous beam of pulsed energy is transmitted from the Transmitter in all directions into the atmosphere, which hits the target and a proportionate amount of energy reflects back to the aerial.
When the Speed of the Beams (which travels at a constant rate) is known and is reference to the Time taken by the beams to go and come back at the Receiver the Range is calculated.
Range approximately 20-30 N.M.
Range also depends upon height of the A/c & height of the receiver, A/c operating below a certain altitude remains invisible to the RADAR, depending upon the terrain features near the installation of the RADAR Transmitter unit.
It also depends upon the surrounding nature of terrain where the A/c is operating.
This can be calculated by the simple formulae-
Range/Distance = Speed × Time
The Range determined is in Slant Range.