Omnidirectional microstrip monopole antenna design for use in microwave imaging systems

In this article, a new design of multiresonance monopole antenna for use in microwave imaging systems is presented. The antenna configuration consists of an ordinary square radiating patch, a feed-line, and a modified ground plane with rotated E-shaped slot and conductor-backed plane structures which provides a wide usable fractional bandwidth of more than 135% (2.9–15 GHz). In the presented design, by cutting a rotated E-shaped slot and also by embedding an E-shaped parasitic structure in the ground plane, additional resonances at 10.6 and 14.2 GHz can be achieved. Using these structures, the usable upper frequency of the antenna is extended from 10.3 to 15 GHz. The proposed antenna has a symmetrical structure with ordinary square radiating patch, therefore, displays good omnidirectional radiation patterns even at higher frequencies. The antenna has sufficient and acceptable gain level and also its radiation efficiency is greater than 86% across the entire radiating band. The designed antenna has a small dimension. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:395–401, 2015