LAUSR

In this paper, a compact dual-polarized ultra-wideband dipole antenna is realized by exciting three resonant modes using double-loop (DL) dipoles with stepped exponential-shaped (ES) arms. First, a single-loop (SL) crossed dipole antenna using the modified direct feeding (MDF) structure with ES arms is designed and analyzed to achieve wide bandwidth (1.7–2.7 GHz) with two resonant modes. Second, without increasing the volume of the antenna, one more loop is employed to gain one more resonant mode to enhance the bandwidth into 1.68–3.7 GHz and fractional bandwidth (FBW) up to 75% for VSWR < 1.5. In order to adjust three resonant modes independently, the ES arms of the DL dipole antenna are designed in stepped shapes. The HPBW is 65–70° for 1.7–2.7 GHz (2G/3G/4G) and 95° for 3.4–3.6 GHz (5G). In addition, the proposed antenna can also be designed with a bandwidth of 2.38–6.42 GHz (FBW of 92%) for VSWR < 2, occupying WLAN/4G/5G. As demonstrations, the proposed antennas covering 1.68–3.7 GHz for VSWR < 1.5 (Antenna A) and 2.38–6.42 GHz for VSWR < 2 (Antenna B) are designed, fabricated and measured, and the measured results agree well with the simulations.