Dualband Cylindrical Dielectric Resonator Antenna Employing <formula formulatype="inline"><tex Notation="TeX">${\rm HEM}_{{11\delta}}$</tex></formula> and <formula formulatype="inline"> <tex Notation="TeX">${\rm HEM}_{{12\delta}}$</tex></formula> Modes Excited by New Composite Aperture

A composite aperture has been conceived to excite cylindrical dielectric resonator antenna (CDRA) simultaneously with two different modes, resulting in broadside radiations at two adjacent bands. Threefold objectives of this investigation includes: (i) to realize HEM _12δ mode in a practical CDRA without involving any unwanted hybrid mode; (ii) to explore composite aperture type feed, which serves as equivalent magnetic and electric dipoles to launch HEM _11δ mode and HEM _12δ mode, respectively; and hence (iii) to achieve a dual-mode dualband CDRA without compromising in any enlargement of antenna dimension. HEM _12δ mode is a recent introduction by the present authors as a broadside radiating mode in a CDRA, although this investigation demonstrates a practically feasible application for the first time. Systematic study of newly proposed composite aperture is followed by experimental investigation with a set of prototypes operating at S and C bands. As much as 6 dBi gain with 7-8% matching bandwidth for each operating band has been experimentally demonstrated.