Fig. 8 shows the MPA with Coaxial Cylindrical DR Loading.
DR with a hole improves spurious response without degrading Q.
It eliminates spurious feed radiation and provides very high bandwidth. In this structure, radius of DR is kept fix such as, outer radius is R= 4, while inner radius is r= 2.
Here we have made the feed point free from loading by cutting the DR of the structure A cylindrically with radius of the outer (2mm) from center of the DR and loading is done exactly around the outer. TABLE III shows comparison of %BW and other parameters of the antenna of structure B by varying the height of the DR.