In the full spectrum of electromagnetic radiation, the very high frequency (30~300MHz) to near infrared (750GHz) band is usually called microwave. General data often define the microwave band as 300MHz ~ 3000GHz, and its wavelength range is 1m ~ 0.1mm.

Microwave signals have the following characteristics due to their extremely high frequency and extremely short wavelength:

Because of the high frequency and large amount of information, it is very beneficial to the application in the field of communication technology. Current microwave communications packages

The usable band included has exceeded the entire long, medium and short wave band by more than 1000 times.

It can propagate in a straight line, has a strong propagation direction, as well as high energy and strong reflection ability for metal targets. Because

Therefore, it is beneficial to improve the accuracy of launching and tracking target in radar, navigation and other aspects.

③ It has strong penetration and absorption capacity for different media, thus enabling satellite communications that penetrate the ionosphere at high altitude.

Microwave medical diagnosis, microwave flaw detection, and as a microwave absorbing material and heating body.

The digitization of microwave equipment can realize the confidentiality of communication. The way to achieve miniaturization, high stability and low cost of microwave equipment is the integration of microwave circuits. Due to the metal resonant cavity and metal waveguide and the quality is too large, greatly limiting the development of microwave integrated circuits, and microwave dielectric ceramics made of resonators and microwave tubes, microstrip lines and other components of microwave hybrid integrated circuits, can make the device size up to millimeter order of magnitude, which makes microwave ceramics become the basis and key materials to achieve microwave control functions. Its application is roughly divided into two aspects, two different performance requirements:

One is a functional ceramic used in a dielectric resonator, which is used in a frequency stabilizing element in a solid oscillator including a band pass filter, a frequency divider, a modem, and the like; the other is a dielectric ceramic used in a microwave circuit, which includes a dielectric substrate, a dielectric waveguide, a microwave antenna, a microwave capacitor, and the like used in a microwave integrated circuit (MIC).

Microwave ceramic dielectric is the basic and key material in microwave circuits, which can be used in various aspects. First of all. Similar to General

The indispensable LC circuit of the oscillator, filter, amplifier, etc., can be used as a dielectric resonator, and secondly can be used to collect or store microwave dielectric antenna. In addition, it can also be used to control the dielectric waveguide of the microwave signal transmission direction, as well as the microwave capacitor coupling between circuits or components, and even the substrate and bottom plate carrying the supporting circuit, components and insulation.

Because the volume of metal resonant cavity can not meet the requirements of miniaturization and integration, and some high dielectric constant ceramic body and free space boundary can refract and reflect microwave signals, and easy to integrate, low cost, so it shows an important position in microwave devices.

With the development of 5G technology, ceramic dielectric filters have gradually replaced metal cavity filters as the mainstream. In addition, the integration and componentization of microwave relay machines and global satellite communication systems have put the development of microwave ceramics to a severe test.