Pattern diversity enabled bandwidth reconfigurable MIMO antenna

A novel four-element MIMO antenna with reconfigurable bandwidth characteristics is reported in this paper. The proposed antenna is evolved using a chamfered rectangular monopole operating from 2.2 GHz to 11.3 GHz. The frequency selectivity of the antenna is accomplished by introducing a bandstop filter adjacent to the microstrip feed line of the UWB monopole. The proposed bandstop filter is constructed by introducing a notch in an all-pass filter. The notch band is carefully chosen such that the integration of the filter with the UWB radiator provides resonances centred around 2.4 GHz and 3.6 GHz suitable for WLAN communications. The bandwidth selection is accomplished using feed selection which is enabled using a set of PIN diodes. This makes the antenna work in two distinct operating modes, namely, the UWB mode (2.2 to >12 GHz) and the dual-narrowband mode (D-NB) (2.4 & 3.6 GHz). The research is further extended towards the construction of a MIMO antenna suitable for mobile networks. The prototype of the proposed four-element antenna is fabricated and analysed for S-parameters, radiation, and diversity characteristics. The average gain of the MIMO antenna array is greater than 4.5 dBi in the UWB/D-NB mode. The proposed antenna is suitable for low power UWB communications and high throughput WLAN such as IoT, sub 6 GHz 5 G communications, etc.