This work was supported by the Spanish Ministerio de Educación, Cultura y Deporte (Programa para la Formación del Profesorado Universitario) under grant FPU15/06457, by the Spanish Ministerio de Ciencia, Innovaci´on y Universidades (MCIU) (Contrato Juan de la Cierva-Incorporaci´on) under Grant IJC2018-038440-I, and by the MCIU, AEI, and FEDER (Programa Estatal de I+D+i Orientada a los Retos de la Sociedad) under grant RTI2018-097098-J-I00.An upgraded version of the complementary stripslot radiating element is reviewed. The original radiating element
consists in a microstrip-fed slot in transmission configuration. In the proposed modification, the slot is backed by a cavity in order
to obtain unidirectional radiation. The presence of this cavity changes the behavior of the slot. A new equivalent circuit is
used to propose a design methodology for broadband operation. Two array designs are simulated and implemented: a phased
array and a log-periodic array. Promising experimental results verify the unidirectional radiation and the wide bandwidth of
these antennas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
