From above plot we can see that BW of 15.5% (1.12GHz)
is achieved for H=6.15mm, which is 5.5% higher than BW of
of structure C and 13.3% larger than BW of the antenna
without DR loading. It is the largest BW among all four
structures with h=0.8mm. In the structure C, some portion of
the larger loop in the impedance locus was outside the vswr=2
circle. By cutting the DR of the structure C cylindrically, it
yields hole large loop inside the vswr=2 circle. -0.097dB
means 97.8% rad. efficiency is achieved which is 5.1% larger
than that of the MPA without loading. Here we got 6.25dB
gain and 6.34dBi directivity.