Kurnia Paranita Kartika Riyanti, Eko Setijadi, Gamantyo Hendrantoro, Nurhayati
Vivaldi antennas used in Ground Penetrating Radar (GPR) systems often experience performance degradation at low frequencies due to inefficient radiation and impedance mismatch between the feedline and the tapered slot structure. To address these limitations, this paper presents a compact Vivaldi antenna employing a coplanar waveguide (CPW) feedline integrated with a single-stub matching technique. The stub position is analytically optimized to improve impedance matching over a broad frequency range. The CPW configuration simplifies the antenna structure by placing both the feedline and ground plane on the same substrate layer, resulting in a compact layout and facilitating broadband operation. The proposed antenna is fabricated on an FR-4 substrate with a thickness of 1.6mm and a relative permittivity of ϵr=4.3, with overall dimensions of 80×80×1.635 mm3. The measured results demonstrate broadband operation from 1.13 to 5 GHz. The antenna achieves a peak gain of 10.89 dBi in simulation and 10.36 dBi in measurement at 1.9 GHz, with a measured radiation efficiency of approximately 90.16% at the resonant frequency. The corresponding simulated and measured S11 values of −61.21 dB and −39.13 dB indicate effective impedance matching at resonance, with minor discrepancies attributed to fabrication tolerances and measurement conditions. To assess practical feasibility, a preliminary sandbox-based GPR experiment was conducted using a pair of identical antennas in a bistatic configuration. The resulting A-scan response shows a distinct reflection corresponding to a buried metallic target at an estimated depth of 37.7 cm, which agrees well with the actual burial depth. These results indicate that the proposed antenna can support broadband GPR sensing within the investigated frequency range, while further system-level and field validations are recommended. © 2026
Department of Electrical Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia; Department of Electrical Engineering, Universitas Negeri Surabaya, Surabaya, Indonesia
