UWB single arm spiral antenna on an EBG substrate
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Abstract
Electromagnetic band-gap (EBG) structures exhibit unique electromagnetic properties that have led to a wide range of applications in electromagnetic devices. In this study, electromagnetic bandgap structures are utilized to enhance the bandwidth of a low-profile one-arm Archimedean spiral antenna built on a thin substrate and backed by a ground plane. It is well known that placing a ground plane (a perfect electric conductor) closely behind a spiral antenna to make the radiation unidirectional severely limits the antenna bandwidth. In order to mitigate the ground plane effect, thus, significantly increasing the bandwidth, electromagnetic bandgap structures are employed. Specifically, the one-arm spiral is placed over an EBG surface which in turn is backed by a ground plane. The EBG surface investigated for this antenna utilizes a periodic structure of rectangular patches. The EBG surface behaves as artificial magnetic conductor in the frequency band of operation. The novel antenna configuration is investigated theoretically using Ansoft Designer which uses a full-wave method of moments solver. Parametric study to understand the effect of geometrical and substrate parameters on antenna performance is carried out. It is shown that the novel antenna design with the EBG surface significantly improves the antenna bandwidth. The design details along with simulation and experimental results will be presented.