Figure 1 also indicates the basic components that make up a phased array. They consist of a power divider/combiner, phase shifters, and radiating elements. This simple sketch understates the tremendous number and variety of components that make up array technology, and it also understates the importance of an overriding array architecture aimed at satisfying the system needs. The following paragraphs will illustrate some of these issues.
Architecture is the character and style of building of a structure or system. The term array architecture implies that there are significant choices to be made in the design of an antenna array system; these choices can completely change the design, packaging, cost, and function of the system. The architecture ofthe system needs to be determined by the antenna system engineer working with the radar, communications, and avionics system engineers.
One type of an array may be an ideal solution for a requirement at, say, 12 GHz but altogether inappropriate at 120 GHz. The 12 GHz design may be a waveguide array with ferrite phase shifters, but at 120 GHz active solid state circuitry may have replaced the ferrite phase shifters, microstrip replaced the waveguide, patch radiators replaced the waveguide elements, and monolithic fabrication replaced the machined part fabrication. These two arrays will therefore have completely different architectures.
This section will describe some of these components and illustrate the interdependence of system architecture and component selection.