Dual Band CPW-Fed Double Monopole Antenna for 2.4/5.8 GHz ISM band Medical Applications
The conception and realization of a dual-band coplanar waveguide fed double monopole antenna, working at 2.4 and 5.8 GHz Industrial, Scientific and Medical (ISM) bands, is presented in this paper. To operate effectively at the aforementioned bands, the designed antenna consists of a symmetrical folded long monopole and a short monopole which are responsible of the resonant frequencies at 2.45 and 5.8 GHz, respectively. Furthermore, both monopoles are fed by a coplanar waveguide. The symmetrical configuration allows the proposed antenna to obtain symmetrical radiation patterns. Hence, an omnidirectional radiation pattern is obtained at 2.45 and 5.8 GHz. A detailed parametric study and antenna parameters are reported and the proposed antenna is designed, fabricated and measured in free space. The proposed antenna has a compact size with the overall dimensions of 30 mm × 27 mm × 1.6 mm. It is concluded from the measured results, that the presented antenna could be considered for applications operating at 2.4 and 5.8 GHz ISM bands. Next, a metallic reflector was introduced to the planar structure in order to improve the gain and provide better directivity for onbody applications, for instance wireless capsule endoscopy systems. For this specific application, the antenna will act as receiving antenna and hence will be held by the patient, which requires a primary on/in-body investigation next to the small intestine region (complex organ of the gastrointestinal tract), as discussed in the paper using multi-layer and voxel models. It is concluded that the proposed antenna structure is a good receiving antenna for wireless capsule endoscopy systems.