**3. Conclusion**

To mitigate the frequency interference from narrowband system like WLAN, a compact planar UWB antenna with single band-notched characteristics for portable wireless devices applications is discussed in this chapter. In this design, the monopoles are arranged perpendicularly to reduce to mutual coupling. A rectangular strip is extended from the ground plane to improve the impedance matching characteristics and to reduce the mutual coupling further or enhance the isolation. An inverted U-shaped slot is used on the feed line to realize the band-notch filtering function for suppressing the frequency interference from 5 to 5.9 GHz WLAN band. For validating the simulation results, all the proposed antennas have been fabricated and tested using the Agilent N5224A PNA, Anritsu MS2037C vector network analyzer and an anechoic chamber. The measured results of all the proposed antenna are well agreed with simulated results. The measured and simulated results show that the proposed antenna offer good impedance bandwidth of *S*11≤ 10 dB in whole UWB band (3.1–10.6 GHz) except at the designed notch bands while giving less mutual coupling (*S*21) of lower than 20 dB in the entire UWB band. The low envelope correlation coefficient, nearly constant gain, stable radiation patterns, more directive gain, TARC and less group delay, demonstrate that the proposed MIMO antenna is an appropriate choice for portable wireless UWB systems.
