Development and design of aluminium nitride disc for high power S-band dielectric window

Abstract

This study deals with the development of aluminum nitride (AlN) disc for an S-band pillbox-type dielectric window that can handle a peak and average power of 6 M W. and 6 kW, respectively, with a negligible reflection and transmission loss. Pure and Er2O3 doped AlN ceramics with diameters and thicknesses of 10 mm and 5 mm are prepared by solid-state reaction method and sintered by adopting the sintering bed (the combination of AlN/C) at 1700 °C. Interestingly, it prevented the formation of Al2O3 completely. The X-ray diffraction patterns of both pure and Er2O3 doped samples displayed wurtzite crystal structure with the P63mc space group. Compared to the pure samples, the AlN ceramics doped with Er2O3 exhibited microwave dielectric properties (εr = 7.81 and tanδ = 5 × 10−4). The dielectric window is designed in CST by using the experimentally derived dielectric properties. The theoretical value of insertion loss and the return loss of the window is better than 61.25 dB and 0.009 dB, respectively, at a rate of 3.7 GHz.

Keywords

• Dielectric window
• Insertion loss
• Microwave dielectric properties
• Pillbox