ABSTRACT
The electronically scanned array (ESA) antenna elements are positioned in the x-y plane and are assumed to radiate in the +z direction or the forward hemisphere. When computing the spatial pattern for an ESA it is important to delineate what coordinate system is being used. Depending on the application, some coordinate systems may be more advantageous than others. From a radar perspective, this coordinate system is more intuitive than that of antenna coordinates. In a radar system, the ESA main beam is typically scanned in some type of raster fashion where the beams are distributed spatially in rows and columns. In a real system application, an antenna engineer may be using a coordinate system different than the system engineer. An alternative to using angular coordinates for modeling ESAs is the sine space representation. Sine space is simply a hemispherical projection of three-dimensional space onto a two-dimensional surface, this chapter graphically illustrates how three-dimensional space is mapped into two-dimensional space.
