ultra wide band branch line combiner

hi everybody
i'm really confused with designing of an ultra wideband (UHF full band) power combiner with branch line structure. i've found that branch line is better than wilkinson for wide band applications but the result of my simulations does not confirm it. it seems design of a branch line (90 deg hybrid) for UHF full band is impossible.
is there any key note to consider?
thanks

http://astro.berkeley.edu/~greg/arnu...2005862657.pdf