In today’s world, microwave dielectric materials play a vital role with a wide range of applications from terrestrial and satellite communication including software radio, GPS, and DBS TV to environmental monitoring via satellites.Improved or new microwave components based on dielectric materials and new designs are required for meeting the specific demands of the current and future systems. The modern advancement in microwave telecommunication, satellite broadcasting and intelligent transport systems (ITS) has resulted in an increasing demand for dielectric resonators (DRs), which are low loss ceramic pucks used mainly in wireless communication devices. With the recent revolution in mobile phone and satellite communication systems using microwaves as the carrier, the biggest challenges for the materials scientists have been the miniaturization of the device.This revolution is apparent on a daily basis in the ever increasing number of cell phone users. The importance of miniaturization cannot be overemphasized in any hand-held communication application and can be seen in the dramatic decrease in the size and weight of devices such as cell phones in recent years. This constant need for miniaturization provides a continuing driving force for the discovery and development of increasingly sophisticated materials to perform the same or improved function with decreased size and weight. In this pursuit, material scientists have developed some dielectric oxide ceramics, which have revolutionized the microwave wireless communication industry by reducing the size and cost of filter, oscillator and antenna components in applications ranging from cellular phones to global positioning systems.

A dielectric resonator (DR) is an electromagnetic component that exhibits resonance with useful properties for a narrow range of frequencies. The resonance is similar to that of a circular hollow metallic waveguide except for the boundary being defined by a large change in permittivity rather than by a conductor. Dielectric resonators generally consist of a puck of ceramic that has a high permittivity and a low dissipation factor. The resonant frequency is determined by the overall physical dimensions of the puck and the permittivity of the material and its immediate surroundings. The key properties required for a DR are high quality factor (Qf), high relative permittivity (εr) and near zero temperature coefficient of resonant frequency ({C}{C}{C}τf). An optimal DR that satisfies these three properties simultaneously is difficult to achieve in a particular material.

Technological improvements in DRs have contributed to considerable advancements in modern wireless communications. Ceramic DRs have the advantage of being more miniaturized as compared to traditional microwave cavities, and have a significantly higher quality factor.

Ceramic DRs have wide spread application. The low permittivity ceramics are used for millimeter-wave communication and also as substrates for microwave integrated circuits. The medium εr ceramics with permittivity in the range 25–50 are used for satellite communications and in cell phone base stations. The high εr ceramic materials are used in mobile phones, where miniaturization of the device is very important. For millimeter-wave and substrate application, a temperature-stable low permittivity and high Qf (low loss) materials are required for high speed signal transmission with minimum attenuation.1

Some of the ceramic materials that are used for DR manufacturing are BaTi4O9, Ba2Ti9O20, Ba[Zn1/3Ta2/3]O3 known as (BZT), Ba[Zn1/3Nb2/3]O3 known as (BZN),Ba[Mg1/3Ta2/3]O3 known as (BMT),ZrTiO4 etc. As DRs made from these ceramic materials have revolutionized the wireless communication, especially the cellular phone and GPS system, they are called “talking ceramics”.

Recent researches focus on developing ceramic materials with A[B’1/3 B’’ 2/3]O3 complex perovskite structure. By sintering under optimum conditions and optimum doping levels, these materials produce attractive properties, especially the ultrahigh values of the quality factor Qf. Some of the materials that are investigated in recent times for DR applications are BZT, BMT, BZN etc.

Ba[Zn1/3Ta2/3]O3 compound termed as (BZT), a member of the A[B’1/3 B’’ 2/3]O3 family of high Qf dielectric materials has potentialfor applications in satellite broadcasting at frequencies higher than 10 GHz and as a very high Qf dielectric resonators (DR) in mobile phone base stations or combiner filter for PCS applications.2 The best properties achieved by BZT for DR application is where the dielectric constant reaches about 31 and a quality factor normalized to 10 GHz up to 13 500.

Like BZT, Ba(Mg1/3Ta2/3)O3 compound known as (BMT) is another member of the A[B’1/3 B’’ 2/3]O3 family of high Qf dielectric materials.3 Its dielectric constant varies between 27 and 32 while the Qf value can reach up to 325 000GHz at a frequency of 13.25 GHz.

Similar to BMT, Ba(Zn1/3Nb2/3)O3 compound termed as (BZN) is also a member of the A[B’1/3 B’’ 2/3]O3 family of high Qf dielectric materials. The BZN exhibits εr of 40, Qf of about 80 000 GHz and f of about 30 ppm/0C.4

Microwave dielectric ceramics are being developed for a variety of applications such as miniaturization for mobile phones, a transmitter and receiver with high performance for base station and millimetrewave applications for ultra speed wireless LAN and ITS. So, there is a huge scope for research in this field.


  1. Mailadil T. Subastian, “Dielectric materials for wireless communication”.
  2. DESU S., O'BRYAN H. M., “Microwave loss quality of Ba[Zn1/3Ta2/3]O3 ceramics”, J. Am. Ceram. Soc., vol. 68, no. 10, pp. 546-551, 1985.
  3. S. Nomura, K. Toyoma, and K. Kaneta. “Ba[Mg1/3Ta2/3]O3 ceramics with temperature stable high dielectric constant and low microwave loss”. Jpn. J. Appl. Phys. 21(1982) L624–L626.
  4. S. Kawashima, M. Nishida, I. Ueda, H. Ouchi, and S. Hayakawa. “Dielectric properties of Ba(Zn1/3Nb2/3)O3–Ba(Zn1/3Ta2/3)O3 ceramics”. Proc. 1st Meeting Ferroelectric Materials & Their Applications. O. Omoto and A. Kumada, (Eds), Keihin Printing Co., Ltd, Kyoto, Tokyo (1977) pp. 293–296.


Adnan Mousharraf has won both University Merit Award and Dean's list Scholarship from Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh.