Magneto-electric (ME) effects in bi-layer multiferroics consisting of single crystal hexagonal SrAlxFe12 − xO19 ferrites (hexaferrites, where x = 0, 0.8, 1.2) and PbZrTiO3 (PZT) have been studied. The main objective of the study was to determine the effect of the Al doping concentration on the ME coupling. We experimentally demonstrate that the Al doping improves dramatically the magnetically induced ME voltage. Moreover, our data indicate that the ME response is a linear function of both ac and dc applied magnetic fields. This is in contrast to previously reported multiferroic laminates that show a non-linear magneto-electric induced voltage as a function of the applied dc magnetic field. The multiferroic structures reported in this work have therefore enhanced functionality because they can linearly operate as a dual ac/dc magnetic field sensors.