Eur. Phys. J. B (2016) 89: 92
https://doi.org/10.1140/epjb/e2016-60671-0

Regular Article

Microwave dielectric properties of Ba(Zn_1/3Ta_{2 / 3})O₃ for application in high power waveguide window^*

¹ School of Physics, University of Hyderabad, 500046 Hyderabad, India
² Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hyderabad, 500046 Hyderabad, India

^a e-mail: kcjrsp@uohyd.ernet.in

Received: 12 August 2015
Received in final form: 27 November 2015
Published online: 11 April 2016

Abstract

Higher dielectric constant, low dielectric loss and good transmission characteristics have been the goal for developing the ceramic waveguide window for high power window applications. The choice of materials having high k with low dielectric loss and reduced window size is key parameters to achieve maximum microwave transmission without unleashing microwave dissipation. The microwave dielectric properties of synthesized Ba(Zn_1/3Ta_{2 / 3})O₃ (BZT) ceramics have been studied for high power window applications. The structural studies are correlated with microwave dielectric properties of BZT. The maximum values of dielectric constant ϵ_r = 30, Q × f₀ = 102 THz and near zero temperature coefficient of resonance frequency were obtained for BZT ceramics sintered at the temperature of 1550 °C for 4 h. The measured results are used to design a tapered transition from air filled waveguide to narrow (reduced width and height) dielectric filled waveguide using Heckens linear taper at a specific frequency. The simulation result shows that the lower reflection loss is obtained for the tapered transition of the narrow BZT window as compared to the standard waveguide BZT window. The return loss of –34 dB is obtained for S-band waveguide window with a bandwidth of 675 MHz. The return loss observed in the narrow BZT window is –46 dB with a bandwidth of 570 MHz at a center frequency of 3.63 GHz. Most of the disadvantages in conventional windows will be rectified using the design of the taper transion employing narrow waveguide window in high power applications.