Design method for antenna arrays employing ferrite printed transmission line phase shifters

Ferromagnetic substrates are attractive for microstrip antenna array applications. An alternative method for using ferrites for beam steering with microstrip arrays is demonstrated. In addition, a method is presented to determine the optimum applied bias field values for maximising the array´s beam steering angular span. The method relies on a knowledge of the propagation constant (β_eff) behaviour within the ferrite substrate, and the finite element-boundary integral (FE-BI) method is employed for extracting β_eff. Experimental and numerical data are included for validating the evaluation of β_eff. To account for finite magnet dimensions, a static analysis is conducted to account for field spatial variations associated with the bias field. These spatial variations must be taken into account to properly model the ferrite propagation constant behaviour. Results are shown for this alternative array configuration, which achieves scan angles as large as 18°