INVESTIGATION OF THE EFFECTS OF DIFFERENT FEED LINE STRUCTURES ON UWB ANTENNA PERFORMANCE BY CHARACTERISTIC MODE ANALYSIS

Abstract

This study investigates the effect of various feed topologies on the parameters of a novel ultra-wideband (UWB) antenna using characteristic mode analysis. The proposed design is guided by characteristic mode analysis, commencing with a basic square structure. Initially, a closed-form estimate of the resonance frequencies of the primary modes is provided for the square-shaped structure. Subsequently, the characteristic modes that resonate in the frequency spectrum are modified by introducing symmetrical square slots. To excite these modes and achieve a wideband antenna that encompasses the relevant spectrum, the geometry of the feeding line is altered and its effects are examined. The study incorporates two fundamental feed line geometries: tapered and traditional feed impedance lines. The proposed UWB antennas are fabricated and measured to validate their performance. According to the measurement results a wide impedance bandwidth of 147.82% at -10 dB reference ((0.9–6 GHz)) and stationary radiation patterns across the operating frequency band are obtained for the tapered feed line. The results demonstrate a significant advantage of the tapered feed line over the traditional impedance line. The results for the fabricated prototypes exhibit high similarity to the simulated results. The findings confirm the applicability of the mode analysis method.