A multiband proximity-coupled-fed flexible microstrip antenna for wireless systems

A multiband printed microstrip antenna for wireless communications is presented. The antenna is fed by a proximity-coupled microstrip line, and it is printed on a flexible substrate. The antenna has been designed using a general-purpose 3D computeraided design software (CAD), CST Microwave Studio, and then realized. The comparison between simulated and measured results shows that the proposed antenna can be used for wireless communications for WLAN systems, covering both the WLAN S-band (2.45GHz) and C-band (5.2GHz), and the Wi-Max 3.5GHz band, with satisfactory input matching and broadside radiation pattern. Moreover, it has a compact size, is very easy to realize, and presents a discrete out-of-band rejection, without requiring the use of stop-band filters. The proposed structure can be used also as a conformal antenna, and its frequency response and radiated field are satisfactory for curvatures up to 65°.