Coaxial-to-rectangular waveguide transition of end launcher has been analyzed and computed detailedly.But the coaxial-to-rectangular waveguide is rarely used as a radiation element for it is difficult to match with free space.This paper applies both loop coupling approach and FDTD method to analyze the three-dimension non-even antenna element

not only reduces computing time and volume

but also improves the accuracy

then gets the radiation pattern and VSWR characteristic figure

proves it with experiment

and solves the match problem of free space.The research proves that this phased array radar element has characters of broadband、big scanning angle

which can be used in ground、airborne and satellite phased array radar or communication system.