is there someone know co-co antenna?

Hi,

I think you probably mean coaxial colinear antenna, don't you? (sometimes it is spelt as 'collinear').

Some links:

http://www.angelfire.com/extreme/sid...collinear.html

http://www.qsl.net/n9zia/wireless/col432/index.html

http://www.rason.org/Projects/collant/collant.htm

and a more complex co-co array: http://www.profiler.noaa.gov/npn/abo...rs.jsp?print=1

So I have been aware of coaxial colinear antennas but did not really recall it is nicknamed as co-co antennas

rgds
unkarc