A fluidically-tunable, dual-band patch antenna

We present a new technique to design a dual-band patch antenna whose response can be changed dynamically using a fluidic tuning mechanism. Using this technique, a dual-band patch antenna operating at 2.5 GHz is designed. Two oil-filled channels are placed in the substrate of the antenna along the non- radiating edges of the patch antenna and filled with liquid (or solid) metal cylinders. As the cylinders are introduced underneath the patch antenna, it starts to exhibit a dual-band response. The separation between the frequencies of the two bands is a function of the relative position of the metallic cylinders with respect to the patch antenna. As the overlap volume between the metal cylinders and the patch antenna increases, the frequency of the first band, f₁, starts to decrease and that of the second band, f₂, increases. The maximum separation between f₁ and f₂ is achieved when half of the length of the metallic cylinder is underneath the patch. The prototype device designed in this work can achieve frequency ratios in the range of f₂/f₁= 1.08 - 1.26. The antenna demonstrates similar radiation characteristics at both bands of operation.