Analysis of a Compact 4-shaped Annular Ring Ultra Wideband Antenna Using Characteristic Modes

This communication proposes a compact 4-shaped monopole annular ring UWB antenna design. The proposed structure contains multiple radiating strips inside the annular ring, in the form of a 4-shaped and a 50Ω microstrip feed line. A tapered structure with a feed point is chosen to achieve wideband characteristics. The proposed model is printed on a low-priced FR4 substrate with a size of 0.180λ 0 × 0.225λ 0 (20 × 25mm 2). The proposed model achieves a fractional bandwidth of 133.74% in the 2.7 to 13.6 GHz range with S11