Nowadays, Beidou antennas are increasingly used in our lives, such as personal location services. When you enter unfamiliar places, you can use a mobile phone or car mounted satellite navigation device equipped with Beidou antennas to provide us with the route to take; Although the Beidou antenna has made our lives more convenient, we have to pay attention to its performance indicators because these indicators determine its functionality. So, what are the performance indicators of the Beidou antenna?

Beidou antenna

1. Input impedance: Input impedance is the ratio of voltage to current at the feeding point of the Beidou antenna. The input impedance of a typical Beidou antenna is a complex number, and the real part is called the input resistance, represented by Ri; The imaginary part is called the input reactance, represented by Xi. And the input impedance of the Beidou antenna is related to factors such as the geometric shape, size, feeding point position, operating wavelength, and surrounding environment of the antenna.

2. Directional diagram: A directional diagram is a graphical representation of a directional function that can vividly depict the spatial distribution of electric (magnetic) field intensity. The width of the directional diagram is often represented by the general power lobe width. Because the directional pattern of the Beidou antenna is determined in the far-field region, it is also known as the far-field directional pattern.

3. Gain: The ratio of the square of the field strength of a certain antenna in the maximum radiation direction to the square of the field strength generated at the same location by an ideal undirected point source, under the same input power of the Beidou antenna. It quantitatively describes the degree to which a Beidou antenna concentrates input power for radiation. The gain is closely related to the antenna pattern, with narrower main lobes and smaller side lobes resulting in higher gain. Commonly used decibel notation, with the symbol dB.

4. Polarization: The polarization characteristics of the Beidou antenna are defined by the spatial orientation of the electric field strength vector of the electromagnetic waves radiated by the antenna in the maximum radiation direction, which describes the spatial orientation of the electromagnetic wave vector radiated by the Beidou antenna. Due to the constant relationship between electric and magnetic fields, the spatial orientation of the electric field vector is generally used as the polarization direction of the electromagnetic waves radiated by the Beidou antenna. Generally divided into linear polarization, circular polarization, and elliptical polarization.

5. Standing wave coefficient (VSWR): The VSWR is a characteristic parameter on the feeder line of the Beidou antenna, which reflects the degree of matching between the input impedance of the antenna and the characteristic impedance of the feeder line. It is defined as the ratio of the maximum voltage to the minimum voltage on the feeder line. If the value of SWR is equal to 1, it means that the radio waves transmitted to the Beidou antenna are not reflected and are all emitted, which is the most ideal situation. If the SWR value is greater than 1, it means that some of the radio waves are reflected back and eventually become heat, causing the feeder to heat up.