Microstrip Patch Array Design

Antenna arrays offer improved directivity compared to a single-radiator antenna. The directivity of an array is due to interference effects between the individual elements of the array, which means that the spatial distribution of the elements as well as phases and magnitudes at each element need to be tuned for optimal performance.

Both the radiation pattern and S-parameters of the array is decided by several factors: the design of the individual patch element, the arrangement and spacing of the array, and the layout of the feed network. Each of these can be considered separately by dividing the process of designing the array into separate stages. By creating the array in steps, the task of optimizing the design is made less challenging, and the most appropriate tools can be used at each stage.

One common application of printed arrays is in wireless local area networks (WLAN). This article explains the design process for a planar microstrip patch array for WLAN frequencies using the circuit and full-wave 3D solvers and optimization tools in CST STUDIO SUITE®. The goal in this case is to design an array with high directivity, low cost and low sidelobes, exhibiting a good impedance matching in the frequency range 5.18 – 5.85 GHz. The same approach can also be used to design other types of array by using a different radiator or array layout.