Many of the threads on the Windsurfer type antenna booster talk about the kind and arrangement of the metallic material used as the reflector. Typically aluminum or copper tape or sheet is used. One area of concern is how smooth the surface needs to be in order to prevent losses from spurious reflection. I've been doing some research on microwave antennas and came across this paragraph in the ARRL Antenna Book, 22cd edition (page 15-59). The specific discussion is for parabolic reflectors but the passive element reflector design of the Windsurfer should follow the same physics. At 2.4 GHz that comes out to 1.25 cm / 8 = .15 cm = 1.5 mm. That is a comfortably large number for smoothness. So, assuming no other factors are involved, any reasonably smooth surface should be adequate. Any thoughts?