A Compact Bowl-Shaped Ring-Loaded Antenna Designed Using Characteristic Mode Analysis for Multiband Base Stations

A compact dual-band antenna element is presented that operates in the bands 0.617-0.894GHz (36.7% fractional bandwidth), and 1.69-2.4 GHz (34.7% fractional bandwidth). The dual-band antenna element consists of a low-band bowl-shaped antenna with a ring for the low-band and a high-band dipole antenna, placed in the center of the bowl. The ring is used to reduce the size of the dual-band antenna element without compromising the bandwidth. The presence of the ring can introduce spurious resonance m