(l) Miniaturization

(high dielectric constant. r). As is well known, the way to achieve miniaturization, high stability and low cost of microwave equipment is the integration of microwave circuits. In the process of microwave circuit integration, the metal waveguide realizes the integration of planar microstrip, and the microwave tube realizes the miniaturization. However, due to the large volume and weight of various metal resonant cavities in microwave circuits, it is difficult to integrate with microstrip circuits. The way out to solve this difficulty is to use microwave dielectric ceramic materials to make resonators. It is known that the size of the resonator is inversely proportional to the square root of the dielectric constant of the dielectric material. Therefore, the larger the dielectric constant of the dielectric material, the smaller the required dielectric ceramic block and the smaller the size of the resonator. Therefore, the high dielectric constant of the microwave dielectric ceramic material is conducive to the miniaturization of the microwave dielectric filter, which can make the filter, together with the microwave tube and the microstrip line, realize the hybrid integration of the microwave circuit, make the device size reach the millimeter order of magnitude, and its price is much lower than that of the metal resonant cavity. General requirements:> 1O.

(2) High stability

(near zero frequency temperature coefficient, f). The working environment temperature of the communication device cannot be fixed. If the resonant frequency of the microwave dielectric material changes greatly with temperature, the carrier signal of the filter will drift at different temperatures, thus affecting the performance of the device. This requires that the resonant frequency of the material does not change too much with temperature. The practical required range of temperature is approximately -40°C to 100°C, in which range the frequency temperature coefficient f of the material is not more than 10 ppm/°C. At present, the temperature coefficient of frequency of microwave dielectric ceramic materials can reach 0 ppm/℃, which can achieve high stability and high reliability of the device.

(3) Low loss

(high quality factor Q). An important requirement of the filter is low insertion loss, and the dielectric loss of microwave dielectric material is a major factor affecting the insertion loss of the dielectric filter. The Q value of microwave dielectric material is inversely proportional to the dielectric loss tand. The larger the Q value, the lower the insertion loss of the filter.
 
To sum up, dielectric ceramic materials are now sweeping the microwave market at a very fast pace of development, and mastering the formula of new ceramic materials has become the new darling of various microwave manufacturers.