Ceramic antenna is a kind of miniaturized antenna. The material of the antenna is ceramic shell, which has the ability of anti-interference, anti-lightning, waterproof and dust-proof. Its weight is only 200g, and the reading distance can reach 2 meters. Because of its relatively close reading distance, it is also known as the short-range antenna. The frequency range is generally between 902MHz and 928MHz. It is a very suitable antenna for Bluetooth devices.

Ceramic antennas have four important parameters

Gain is one of the main indicators of ceramic antenna, which is the performance of the radiation or received radio wave size of ceramic antenna. The choice of gain size depends on the requirement of the radio coverage area in the system design. Simply put, the higher the gain, the further the radio waves travel under the same conditions.

Standing wave (VSWR) According to the test of feeder transmission efficiency, the voltage standing wave ratio is less than 1.5, and the voltage standing wave ratio is less than 1.2 at the operating frequency point. If the voltage standing wave ratio is too large, the communication distance will be shortened, and the reflected power will return to the power amplifier of the transmitter, which is easy to burn out the power amplifier tube and affect the normal operation of the communication system.

Working bandwidth: The electrical parameters of ceramic antenna are generally related to the working frequency, and the allowable frequency range of the electrical parameters is the working frequency band width of the ceramic antenna. Generally, the operating bandwidth of omnidirectional ceramic antenna can reach 3-5% of the operating frequency range, and the directional operating bandwidth can reach 5-10% of the operating frequency range.

Directivity: Ceramic antenna has different radiation or receiving capacity in different directions in space, which is the directivity of ceramic antenna.

The working principle of ceramic antenna is divided into two parts, one is the transmitting antenna, the other is the receiving antenna, the transmitting antenna is simply through an electrode called "antenna" formed between the antenna and the ground into the high-frequency electric field into electromagnetic waves, so that it can be emitted and spread to the distance. The receiving antenna uses an electrode called "antenna" to induce the electromagnetic wave from the air into an electric field, generate a high-frequency signal voltage, and send it to the receiver for signal processing.

In the design of ceramic antenna unit, high frequency and low noise amplifiers are used to reduce the influence of antenna thermal noise and the previous stages of the unit circuit on the performance of the receiver. The role of ceramic antenna is to convert the electromagnetic wave energy of the radio signal from the satellite into the current that the electronic components of the receiver can absorb and apply, so the size and shape of the antenna are very important.

The types of ceramic antenna are divided into block ceramic antenna and multilayer ceramic antenna. Block antenna is to sintering the whole ceramic body in one time at high temperature, and then the metal part of the antenna is printed on the surface of the ceramic block, while the multi-layer antenna firing adopts the way of low-temperature co-firing, and the multi-layer ceramic superposition is then sintered at high temperature. Therefore, the metal conductor of the antenna can be printed on each ceramic medium layer according to the design needs. Because the dielectric constant of the ceramic itself is higher than that of the pcb circuit board, the ceramic antenna can effectively reduce the antenna size, and can achieve the purpose of hiding the antenna.