A Planar UWB Diversity Antenna

A planar dual-port diversity antenna, operating with broadside and/or conical radiation patterns in H-planes, is presented for ultrawideband (UWB) applications. The proposed antenna consists of a suspended square patch with a thick stem underneath. A broadband differential feeding strip is used to feed the square patch. The measured gain for the broadside mode is 8.4-10.3 dBi from 3.1 GHz to 5.2 GHz (50.6%), and the conical mode 3.2-5.1 dBi from 3.1 GHz to 4.9 GHz (45%). The measured reflection coefficients (vertical bar S-11 vertical bar, vertical bar S-22 vertical bar) are less than -10 dB over the frequency ranges and the isolation vertical bar S-21 vertical bar between the two ports is greater than 13.5 dB. The operation of the differential feeding strip on the antenna is discussed. Both pattern diversity and partial polarization diversity are achieved for this antenna.