Array antenna characteristics improvement: Parasitic patches (two disposals) and multi layer substrate techniques

This paper will introduce the approaches for characteristics improvement of patch array antenna for electronic scanning radar application. The basic array antenna is designed on FR-4 substrate and we have used microstrip technique as feeding. This antenna is based on 8 patches operating at frequency 3GHz. This structure has two disadvantages; a low gain value caused by the lossy nature of substrate and a narrow bandwidth by dint of microstrip antenna limitations. Thus, the objective of this work is to improve the gain and the bandwidth of the basic structure. For this reason, two techniques will be presented and compared in this paper: Parasitic patches and multilayer techniques. The first one consists on adding a number of parasitic patches, two different ways of parasitic patches dispositions are proposed. The distance between driven and parasitic patches is evaluated. Regarding the second technique, a layer of FR-4 is added to the substrate distanced with air gap which thickness is 0.04xAg. The design and the simulation will be performed using Advanced Design System (ADS) tool. Not only the comparison between basic array antenna and both techniques will be presented, but also the comparison results between simulations of both modified structures using the previous techniques will be performed.