Radiation Pattern Reconfigurable Antenna Using Liquid Metal Vias

Abstract

This paper presents a moderately high directivity (~12 dBi) antenna having a reconfigurable radiation pattern. The proposed antenna, illustrated in Fig. 1 , is closely based on existing designs [1] - [2] . The proposed antenna consists of a driven element, surrounded by four parasitics. Both the driven element and parasitics, are circular microstrip patch resonators and all have a radius of 9.6mm. The driven element is fed using an SMA connector and energy from this element couples into the parasitics. Each parasitic incorporates a chill hole. A key novelty of the work is that we use a commercially available liquid metal (EGaIn) based on an alloy of Gallium to fill the hole and form a via. When the via is in place we say that the parasitic is ON. Consequently that particular parasitic is short circuited to ground, causing it to act as a reflector. This has the effect of reducing the electric field strength on the surface of those patches to a very low level which effectively deactivates the excitation of TMu mode, as shown in Fig. 2(a) and (b) . The beam, therefore steers away from the ON state parasitics. When the via is removed we say that the parasitic is OFF and it acts as a director. The OFF state parasitics have the effect of increasing the aperture area of the antenna and hence the directivity. The antenna is designed on a substrate with a thickness of 1 mm and dielectric constant of 2.7. The overall dimensions of the proposed antenna are 34 mm × 34 mm