Plasmonic metamaterials based on metal-dielectric nanostructures exhibit unique optical properties such as high near-field enhancement, negative refractive indexing, and optical cloaking. In this paper, we present a plasmonic multiband metamaterial based on UT shaped nanoparticles. In order to understand the multispectral response, we analyze the near-field distributions at the corresponding resonance frequencies. In addition, we both numerically and experimentally, show the dependence of the spectral response on the geometrical parameters of the structure. By embedding the system in a dielectric cladding medium, we show strong sensitivities of the resonant behavior to the refractive index and thickness of the dielectric load. Due to its tunable multiband spectral characteristics, the proposed metamaterial antenna can be used for wide range of applications, such as wavelength-tunable active filters, optical modulators, ultrafast switching devices, and biosensing.