Airbourne weather radar (Beams)
Abstract on weather radars:
"The radar can has two modes, weather and mapping. The weather beam is used for detecting clouds and is a conical pencil beam with a width of 5 degrees and the mapping is for ground features and uses a fan shaped or cosecant squared beam.
The directional properties of the radar produce side lobes. One side lobe goes vertically down to the ground and is received back by the weather radar receiver. This received signal produces a height ring on the display. The ring indicates that the radar is working and appears at the approximate height of the aeroplane above the gound. An aeroplane flying at 12000ft will have a permanent return at approximately 2nm."
I would like to know why the weather radar uses a conical pencil beam for detecting clouds and the different fan shaped consecent squared? beam for ground features?
From what i have read i thought that side lobes are useless, that they give false responses outsde the main beam and produces unwanted clutter. Although side lobe is used to determine height on the AWR why is this?
Cheers