The complementary strip-slot element is a broadlymatched
microstrip radiator that has been used to design innovative
series-fed arrays. It consists of a microstrip series-fed slot
that have its complementary stub on the layer of the microstrip
and aligned to the slot. In this contribution, the influence of the
strip and slot geometry on its performance is studied through the
analysis of four different designs. The obtained results highlight
the possibility of controlling the radiation efficiency or the phase
response, without compromising the broad matching. Therefore,
potential series-fed arrays built with this element can exploit this
feature to set the magnitude and phase of the excitations with
certain flexibility.