Why Choose a Parabolic Wire Antenna over a Solid Parabolic Antenna?

[berkeman]

I just saw one of these antennas, and I'm puzzled a bit by it. Why would one choose to use a parabolic wire antenna instead of a solid parabolic antenna? It would seem to be much less efficient at first glance (although I don't know if it is true or not). And how do the wire elements manage to steer the energy to the focal reflector in the horizontal plane in the figure below? I understand how the first reflection works for a standard solid parabolic reflector, but how do the wire elements reflect energy inward toward the focal reflector?

http://m.bectrade.com/p/98/6498_Sell_WiFi_24_dBi_Grid_Parabolic_Antenna.jpg
http://m.bectrade.com/p/98/6498_Sell_WiFi_24_dBi_Grid_Parabolic_Antenna.jpg

 

[I like Serena]

From wikipedia: http://en.wikipedia.org/wiki/Parabolic_antenna

"A metal screen reflects radio waves as well as a solid metal surface as long as the holes are smaller than 1/10 of a wavelength, so screen reflectors are often used to reduce weight and wind loads on the dish. "

and

"A reflector made of a grill of parallel wires or bars oriented in one direction acts as a polarizing filter as well as a reflector. It only reflects linearly polarized radio waves, with the electric field parallel to the grill elements. This type is often used in radar antennas. Combined with a linearly polarized feed horn, it helps filter out noise in the receiver and reduces false returns."