  In the recent years constructing time-invariant spatial-focusing beampatterns
by using frequency diverse arrays (FDAs) is conveyed in several papers. Further
than time-invariant spatial-focusing beampatterns, the unfeasibility of
constructing range-dependent time-invariant beampatterns is demonstrated in
this paper. It is indicated that the beampatterns produced by antenna arrays
including FDAs are not independently controllable in time, t, and range, r,
dimensions, in the farfield. Inappropriate applications of the FDAs having
time-invariant spatial-focusing beampatterns in two recent papers are also
discussed.
