## 1 Introduction  
Microwave dielectric materials play a vital role within a wide range of applications from terrestrial and satellite communication including software radio, Global Positioning Systems (GPS), and Direct Broadcast Satellite (DBS) television and environmental monitoring via satellites. The recent progress 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 [1]. The key properties required for DR materials are high quality factor-frequency product (Q \(\times\) f), high relative permittivity (\(\varepsilon_{\mathrm{r}}\)) and near zero temperature coefficient of resonant frequency (\(\tau_{\mathrm{f}}\)) or temperature coefficient of the relative permittivity (TC\(\varepsilon_{\mathrm{r}}\)). The relative permittivity determines the size of the electronic component, the temperature coefficient of resonant frequency establishes the frequency stability, and the loss tangent (tan8) or quality factor (Q = 1/tan8) controls the selectivity and performance of the device [2]. An optimal dielectric resonator that satisfies these three properties simultaneously is difficult to achieve solely in a particular material. In order to meet the specifications of the current and future systems, improved or novel microwave components based on dedicated dielectric materials and new designs are required [3]. In addition, with the recent evolution in mobile phone and satellite communication systems, using microwaves as the carrier, the research and development in the field of device miniaturization is needed [4]. This fast-growing mobile/wireless communication industry is demanding small size and lightweight integrated components and packages at low cost. A method to meet these requirements, which are now under consideration by the community, is the replacement of the currently used bulk ceramic dielectrics by dielectric thick films [4; 5]. Electrophoretic deposition (EPD) is one of the processing techniques of thick films. EPD is a colloidal process, in which charged particles dispersed in a stable suspension are driven by electric field to move towards oppositely charged electrodes to build up a particulate coating by deposition on one of the electrodes [3; 6; 7; 8; 9; 10]. The main advantages of EPD are related to low cost, versatility and ability to coat conformal substrates. However, the utilization of insulating substrates required for low loss microwave applications raises difficulties for the preparation of continuous thick films by EPD, since to apply the electric field during the EPD process the substrate should be a conductor. Moreover, a high corrosion resistance in the EPD suspension and thermal stability are two major criteria that also limit drastically the use of conductive substrates in EPD [7]. This last aspect is of particular relevance when the thick film sintering temperature is high (>1000 \({}^{\circ}\)C), thus, restricting considerably the choice of electrodes to high temperature conductive oxides or noble metals, such as gold, platinum and palladium; both expensive alternatives. There is, however, an approach developed for preparation of thick films by EPD on poorly conducting substrates, using a fugitive layer of graphite [11; 12]. Moreover, Y-stabilized zirconia (YSZ) films deposited this way on NiO-YSZ for fuel cell application were reported to be of improved quality. In our previous work, we adapted this approach to the more critical case of EPD films on insulating dielectric substrates (as alumina and glass) for electronic applications [13]. Thin sacrificial layers of conducting carbon were coated onto non-conducting alumina substrates to facilitate the conduction on the substrate surface. The carbon coating burns out during the sintering step, not interfering with the final product.