This paper presents the design and experimental investigation of a compact coplanar waveguide (CPW)-fed super-wideband (SWB) antenna employing a modified rectangular patch and a hexagonal slotted ground structure. The proposed antenna is realized on a Rogers RO5880 substrate with a compact physical dimension of 18 × 18 × 1 mm3, corresponding to an electrical size of (0.240 × 0.240λ0) at the lower operating frequency of 4 GHz. The antenna is designed and simulated using CST Microwave Studio software, and it exhibits an ultra-wide operating frequency range from 4 to 85 GHz in simulation, corresponding to a fractional impedance bandwidth of 182%, enabling coverage of multiple frequency bands relevant to 5G/6G wireless communications, millimeter-wave (mm-wave) systems, and microwave imaging (MI) applications. The antenna performance is analyzed in terms of reflection coefficient, radiation pattern, gain, surface current distribution, and group delay. A prototype of the antenna is fabricated and experimentally characterized, demonstrating a measured impedance bandwidth from 4 to 67 GHz (177.5% fractional bandwidth). The measured results show good agreement with the simulated response, confirming stable super-wideband behavior and reliable radiation performance across the validated operating band.
Kumar et al. (Tue,) studied this question.