Dual-Wideband Low-Profile Three-Notch Patch Antenna With Indirect Differential Feeding for 5G Millimeter-Wave Applications

This study presents a dual-wideband, low-profile antenna designed using novel design approaches, operating across the full 5G millimeter-wave bands around 28 GHz and 38.5 GHz. It covers n257, n258, n259, n260, and n261, spanning a total range of 24.25–29.5 GHz and 37–43.5 GHz. The proposed design incorporates a novel three-notch patch (TNP) antenna and an indirect differential feeding (IDF) configuration. The center-located hyperbolic notch and IDF, with the aid of two side-located rectangular notches for higher-band impedance matching, enable dual-wideband operation while also providing high cross-polarization discrimination. The simulated 2:1 VSWR bandwidth of the proposed TNP antenna is 24.2–29.6 GHz (20.1%) and 37.0–44.0 GHz (17.3%). During the fabrication of the array, a compact balun was designed and integrated into the proposed TNP antenna because no commercial RFIC fully covering the n257–n261 bands was available at the lab stage. The measured bandwidth of 20.5% in the lower band and 15.7% in the higher band confirmed its dual-wide bandwidth characteristic.