Wideband Two-Port Symmetrical Monopole Antenna with Broadside and Omnidirectional Radiation

This paper presents a wideband miniaturized Vivaldi antenna with two excitation ports to create broadside and omnidirectional radiation patterns. The antenna is based on two Vivaldi monopoles implemented perpendicularly to a conductive ground plane, and oriented in opposite directions of the vertical symmetry axis. By exciting the ports in- and out- of phase, two orthogonal radiating modes can be excited. These modes present 96% and 120% simulated relative -10dB reflection coefficient bandwidth from 1.5GHz to 6GHz, depending on the excited mode, with total efficiency better than -1 dB. The studied low envelope correlation between the modes is predicting very good diversity or MIMO performance. Also the simulated surface current distributions and related radiation patterns in XY- and XZ-cut at 2 GHz, 4 GHz, and 6 GHz are presented and compared.