Comparison between Keller's and Ufimtsev's theories for the strip

The high-frequency backscattered far field produced by a plane electromagnetic wave obliquely incident on a perfectly conducting infinite strip is considered. A comparison is made between the results obtained by applying Keller's and Ufimtsev's asymptotic theories. It is shown that Ufimtsev's expansion is incorrect beyond the leading term, but that the discrepancy is numerically small. The implications in caustic matchings for more complicated shapes, such as finite cones and disks, are briefly discussed.