Miniaturisation of dual band monopole antennas loaded with screen printed cobalt nanoparticle ink

In this study, miniaturisation of dual band monopole antennas has been investigated with the screen printed magnetic thick films of cobalt nanoparticle ink. The resonant frequencies of antennas were tuned by printing of the ink with different layer thicknesses on top of the antenna elements. The influence of magnetic layers on resonance frequency, return loss, total efficiency and radiation pattern were measured and compared with a reference antenna without layers. For example, five layers of magnetic film (total thickness of 90 μm) on the monopole antenna tuned the frequency by 137 and 297 MHz in the lower (900 MHz) and upper frequency (1800 MHz) bands, respectively. The total efficiency of a magnetic film loaded monopole antenna in the upper frequency band was found to be increased marginally or remain unchanged. The radiation patterns of the antenna remained essentially unchanged, despite the presence and use of the magnetic thick films.