Antenna can be roughly divided into two types of antenna and caliber antenna. VHF and UHF antennas for mobile communications are mostly antenna antennas of various types based on symmetrical oscillators. GPS Antenna Satellite satellite receivers mostly use parabolic antennas (aperture antennas) to receive satellite signals.
The characteristics of the antenna and antenna shape, GPS Antenna size and composition of the material. The size of the antenna is generally measured by the wavelength of the antenna transmitting or receiving electromagnetic waves l. Because the radiation characteristics of a 1 m long dipole antenna operating at a wavelength of l = 2 m are the same as that of a dipole antenna operating at a wavelength of 1 = 2 cm and 1 cm long. Parameters related to the antenna directivity: the directional function or the directional diagram away from the antenna at a distance, the mathematical expression describing the relative distribution of the electromagnetic field intensity of the antenna radiation in space, called the directivity function of the antenna; the directivity function is graphically represented Out, GPS Antenna is the pattern. The largest radiation beam is often called the main lobe of the pattern. Several small beams next to the main lobe called the side lobes.
Antenna gain is a measure of the radiant intensity of an antenna in a given direction of the wavefront. It is the ratio of the radiated intensity of the studied antenna in the direction of the maximum radiation to the maximum intensity of the radiation generated at the same point by the isotropic antenna of the same input power of the studied antenna.
Polarization characteristics refer to the law of the direction of the electric field vector with time in the direction of the maximum radiation. According to the polarized form of the electric field radiated by the antenna, the antenna can be divided into a linear polarized antenna, GPS Antenna a circular polarized antenna and an elliptically polarized antenna. Line polarization can be divided into horizontal polarization and vertical polarization; circular polarization and elliptical polarization can be divided into left-handed and right-handed.
Input impedance and voltage standing wave ratio: The antenna’s input impedance is equal to the characteristic impedance of the transmission line, in order to make the antenna gain maximum power. When the working frequency of the antenna deviates from the designed frequency, GPS Antenna the match between the antenna and the transmission line becomes worse, resulting in that the voltage standing wave ratio on the transmission line increases and the antenna efficiency decreases. Therefore, in practical applications, voltage standing wave ratio parameters are also introduced, GPS Antenna and the standing wave ratio can not be greater than a certain value.
Antenna’s electrical parameters are related to the frequency, when the operating frequency deviates from the design frequency, often cause changes in the antenna parameters.GPS Antenna When the operating frequency changes, the electrical parameters of the antenna should not exceed the specified range, the frequency range is called the bandwidth, referred to as the antenna bandwidth.
Most antennas are reciprocal, GPS Antenna that is, the antenna has the same directivity in transmit mode and receive mode. If a given antenna is operating in transmit mode and its ability to radiate electromagnetic waves in direction A is 100 times stronger than in direction B, GPS Antenna the sensitivity of the electromagnetic waves received in direction A to radiation in receive mode is also 100 times greater than in direction B.
Post time: Sep-25-2018