Efficient Endfire Superdirective Arrays of Printed Dipoles Loaded with CSRRs

This paper discusses implementation of efficient arrays using highly directive dipoles loaded with complementary split ring resonators (CSRRs) for mm-wave applications. A Yagi-like excitation setup is proposed to overcome matching the high input impedance of the used loaded dipole element. As a result, directivity reaches 9.7 dB with radiation efficiency of 91% at 29.88 GHz for an array of three closely spaced elements. Moreover, the 3dB directivity bandwidth is improved from 313 MHz to 642 MHz using an asymmetric dipole element and up to 1001 MHz using a modified CSRR with multiple parallel radiating current strips.