A Compact Self Isolated MIMO UWB Antenna with Band Notched Characteristics

A miniature Multiple Input Multiple Output (MIMO) Ultrawideband (UWB) antenna with C-band notch is recommended for wireless communications. The radiator is etched on an economical FR4 substrate and is 40 x 21 mm(2) in size. The antenna is comprised of a circularly notched rectangular patch embedded with an ellipse and is fed by a 50-ohm microstrip line. To reduce mutual coupling by < -18 dB throughout the whole operational bandwidth of 2.94-11.61 GHz without employing any coupling device, the two radiators are positioned side-by-side with a separation of 0.03 lambda 0 (lambda 0 is the wavelength at the lower cutoff frequency of 2.94 GHz). A U-type slit is cut into the patch to produce the band-notch at C-band across 3.63-4.15 GHz. Results from simulation and experiment concludes that the suggested radiator has a wide impedance bandwidth (S-11< - 10 dB) and strong mutual coupling (S-21 < -18 dB) between 2.94 and 11.61 GHz. Except at the notch frequency of 4 GHz, where the gain is -3.21 dBi, the peak gain and peak radiation efficiency are both 4.21 dBi and more than 82%, respectively. The measured envelope correlation coefficient (ECC) of 0.002, peak diversity gain (DG) of 9.999 dB, and mean effective gain (MEG) of less than -3 dB over operating band, along with the omnidirectional characteristics of the radiator, prove its suitability for use in wireless systems.