Simultaneous Frequency and Isolation Reconfigurable MIMO PIFA Using PIN Diodes

A reconfigurable multiple input multiple output (MIMO) planar inverted-F antenna (PIFA) is presented for three worldwide m-WiMAX bands: 2.3-2.4 GHz, 2.5-2.7 GHz, and 3.4-3.6 GHz. In order to achieve low mutual coupling, i.e., high isolation, a band-notched quarter-wave slot line on the ground plane is used between the two reconfigurable antennas. Two PIN-diodes are appropriately located on the slot line in order to electrically control the slot length. By adjusting both the PIN-diode biases for the reconfigurable antennas and the reconfigurable isolation slot, the proposed antenna simultaneously obtains the operating frequency and isolation reconfigurability for the three operating bands. A parametric analysis is performed to investigate optimized slot lengths for the three operation modes. All of the simulated results are confirmed with measurements. Measured isolation performance of greater than 30 dB improves the radiation efficiency, diversity gain, and channel capacity for all operating frequencies.