Investigation of the far- and near-field performance of a bull's eye leaky-wave antenna with open-stopband suppression

We study a 2-D leaky-wave antenna (LWA) with suppressed open stopband (OSB) operating both in the near- and far-field, offering enhanced performance compared to existing designs. In particular, two configurations, a double strip (DS) and a single strip (SS) bull's-eye (BE) LWA structure, are analyzed and compared. The DS launcher demonstrates superior broad-band performance, maintaining efficient beam collimation across a wide frequency range in the near-field and enabling continuous beam scanning in the far-field as a function of frequency. In contrast, the SS configuration exhibits an open stopband at about 19.2 GHz and without continuous radiation. Both launchers employ a coaxial TM-polarized feed mechanism to ensure optimal power transfer, and dispersion curves show identical crossover frequencies for both BE antenna implementations. However, the suppression of the OSB combined with the wide band capability of the DS configuration, highlights the potential of this design for next-generation high-frequency communications, wireless power transfer, and, radar systems operating in the near- or far-field.