This paper demonstrates the design and development of a dual-operating mode multiple-input and multiple-output (MIMO) antenna. The MIMO antenna comprises a novel ultrawideband (UWB) antenna with selectively chosen feedlines to obtain bandwidth reconfiguration. The novel UWB monopole evolved from a rectangular monopole whose radiating portion and the ground plane are shaped to obtain broadband impedance matching from 2.3 to 10.7 GHz (Mode 1). The antenna is excited using a 50-Ω microstrip line. An additional feed path is created and deployed to achieve bandwidth selectivity with a tuning fork bandpass filter (BPF) operating between 2.8 and 4 GHz. Bandwidth selection is performed using a pair of positive-intrinsic-negative diodes. Thus, in the reconfigured state, the monopole is connected to the excitation source through the BPF, restricting the operational bandwidth to 2.8-4.0 GHz (Mode 2). A vertically polarized four-element MIMO antenna with pattern diversity characteristics is constructed, and the performance parameters are studied. The