A Study of Wideband Dielectric Resonator Antennas Loaded With Special Dispersive Materials

In this paper, a comprehensive study of wideband dielectric resonator antennas (DRAs) loaded with special dispersive materials is given in detail. The concept and theory for a new class of wideband and compact DRAs are introduced for the first time using the new material whose relative permittivity is inversely proportional to the frequency power of n (i.e., $\varepsilon _{r }$ (f) ${=} {k}$ / $f^{n}$ , k is a constant). Traditional DRAs are normally of limited bandwidth and unstable radiation patterns. The proposed new DRAs exhibit excellent advantages in bandwidth enhancement, size reduction, single-mode purity (predominantly supporting a single mode with minimal interference from other unwanted modes), and stable radiation patterns. The new dielectric resonator theory with wideband resonance characteristics is developed. Based on this, wideband and compact cylindrical and rectangular DRAs are designed and studied. The simulated and measured results demonstrate the merits of the proposed antennas. It is shown that without changing the structures, the percentage bandwidth of the proposed cylindrical DRA made of a dispersive material can be significantly increased to 120%, compared to the DRA using the traditional material with a constant permittivity (4%). The paper provides a new approach for making wideband and compact DRAs with stable radiation patterns for future wideband wireless communications and radar applications.