Printed antennas over lossy magneto-dielectric substrates

Since many years there is a growth interest for microstrip antennas due their advantages as for example simplicity, low cost, and compact size. The use of high permittivity dielectric substrates leads to size reduction in printed antennas design, but the antenna performances as the efficiency and the bandwidth are considerably reduced [1–2]. However, the use of magnetic materials can overcome this limitation since they offer a larger bandwidth compared to dielectric materials [3]. But, available magneto-dielectric materials have weak magnetic properties and are rather lossy in the microwave frequency range. So, for design purposes, there is a need to know how magneto-dielectric losses affect printed antennas performances as the radiation efficiency and bandwidth. Of course, dielectric losses have already been studied [4], but in our knowledge, no one has proposed any useful formulas for evaluating magneto-dielectric losses in printed antennas.