Microwave Dielectric Properties of B₂O₃-Doped Nd(Mg_0.4Zn_0.1Sn_0.5)O₃ Ceramics for Application in Inverted-L Monopole Antenna

Abstract

Nd(Mg_0.4Zn_0.1Sn_0.5)O₃ ceramics prepared by the conventional solid-state method have been investigated for application in inverted-L monopole antenna. B₂O₃ was selected as a liquid sintering aid to lower the sintering temperature of Nd(Mg_0.4Zn_0.1Sn_0.5)O₃ ceramics. It was found that the X-ray diffraction patterns of the Nd(Mg_0.4Zn_0.1Sn_0.5)O₃ ceramics exhibited no significant phase difference with 0.25 and 0.5 wt% B₂O₃ additive at different sintering temperatures. The maximum values of the dielectric constant and the quality factor (Q × f) can be obtained when the Nd(Mg_0.4Zn_0.1Sn_0.5)O₃ ceramics with 0.25 wt% B₂O₃ additive were sintered at 1400°C for 4 h. The temperature coefficient of resonant frequency (−65.2 ppm/°C) was measured for Nd(Mg_0.4Zn_0.1Sn_0.5)O₃ ceramics with 0.25 wt% B₂O₃ additive sintered at 1400°C for 4 h. The measurement result of inverted-L monopole antenna at 3.5 GHz was presented. With this technique, a 32.39% bandwidth (return loss < 10 dB) with a center frequency at approximately 3.55 GHz was successfully achieved.

Keywords:

• Nd(Mg_0.4Zn_0.1Sn_0.5)O₃
• X-ray diffraction
• dielectric constant
• quality factor
• temperature coefficient of resonant frequency
• monopole antenna

Acknowledgment

The authors would like to thank the National Science Council of the R. O. C., Taiwan, for financially supporting this research under Contract No. NSC 99-2622-E-262-003-CC3.

Communicated by Dr. George W. Taylor