gambit
PROFESSIONAL
- Joined
- Apr 28, 2009
- Messages
- 28,569
- Reaction score
- 148
- Country
- Location
A poled design is exactly the descriptor 'pole'. The array consists of precisely length-ed and oriented rods arrayed to create a certain beam shape. A true square array would have a conical beam. Deviate from that square and you begin to have a more fan shaped beam.You will have to excuse my ignorance. What is the difference between a poled AESA and an Israeli Greenpine like AESA?
The Israeli Greenpine system, from all descriptions and images available, seems to be a solid state system consists of solid state T/R modules. It is a more advanced design in terms of beam precision, from shape to direction. The antenna itself may have a few mono-poles in precise locations to create several 'anchor' main beams -- when needed -- for multi-beams operations. But this hybrid is generally from older AESA designs. Still useful, though, for development purposes.
Poled designs are not good for when the target is as dynamic as an aircraft or a descending ballistic warhead and it is because of the radiation pattern of a rod. After all, the rod or pole was the first foundation of wireless transmissions in the first place, and the pattern is omni-directional in azimuth (horizontal). The US Pave PAWS early warning system is a phased array composed of thousands of di-pole transmitters and all of them are against a back plane so all the poles' transmissions are directional. The working wavelength is in the mhz bands so the system was high power and long range detection of incoming targets. Good to know direction and coarse resolutions of speed and altitude of the target.
For example...
By 'coarse' I mean target updates are in meter intervals, as in timestamp 00:00 the target is at 1000 meters altitude, and in timestamp 00:10, the target is at 900 meters altitude.
By 'fine', as in solid state design quality, target updates are sub-meter intervals, as in timestamp 00:00 the target is at 1000 meters, and in timestamp 00:00:01 the target is at 999.99 meters altitude.
See the difference?
As the target gets closer and closer, the threat quotient increases, meaning you are going to die soon if you do nothing. So if you are going to do something, either you move out of the way, or you send an interceptor, you want to give yourself and your interceptor as fine grained information about the threat as possible. That is why long range detection can get by with coarse information from easily designed poled systems operating in the meter length wavelength, while tracking and targeting radars must or should have fine and very fine grained data from solid state systems in the centimetric or even millimetric bands.