Angular Localization of Radio-frequency Sources Using a Compact Metamaterial Receive Antenna

Radio-frequency source localization becomes a major challenge for many applications such as beam-steering or MIMO communication. This task is commonly carried out by taking advantage of the adjustable radiation patterns of phased arrays to scan an area. Nevertheless, it can be difficult and expensive to implement in some frequency bands of the last generation of communication systems. Here, we propose an alternative based on a single port compact metamaterial antenna. We use a finite periodic array of sub-wavelength ([lambda]/6) resonators for the design of this antenna. A microstrip line is added to excite the resonator array etched on a grounded low-loss substrate and to use it as a planar antenna. In such an antenna system, the coupling between sub-wavelength resonators is able to induce a strong dispersion and leads to several complex radiation patterns over a specific narrow frequency band. We implement numerical methods to estimate the direction of a target antenna by taking benefits of the complex frequency signatures. We experimentally demonstrate that a single port sub-wavelength antenna made of a finite array of metamaterial resonators is able to retrieve the direction of a narrow band (3.6% relative bandwidth) emitting target around 5.5 GHz with a maximum precision of 3[degrees]. Such a compact planar system ([lambda]/3, [lambda]/2 and 2[lambda]/3) can be used to substitute the phased array localization technique in order to provide the necessary angular information in many applications such as mm-Wave communication and can be extended to high frequency regimes by using the corresponding resonators.