In the formula, S-antenna aperture area (square meters); lambda-working wavelength (meters); D-parabolic aperture (i.e. aperture diameter) (meters); _-antenna efficiency.
Directional pattern If the intensity of the radiation strikes of the anti-antenna in all directions is expressed by the length of the vector starting from the origin, the envelope formed by connecting all the vector endpoints is the pattern of the antenna. It shows the relative radiation of antenna in different directions, which is called stereo pattern. The direction of the vector diameter represents the direction of radiation, and the length of the vector diameter represents the intensity of radiation shock. The pattern contains many lobes, in which the lobe containing the maximum radiation direction is called the main lobe. Others are called first sidelobe, second sidelobe, etc.
Main lobe width It is defined as the width of the gain decreasing by 3 decibels relative to the maximum gain in the directional graph, in units of degree (radian).
Sidelobe level The ratio of the maximum of the side lobe to the maximum of the main lobe is called the side lobe level, which is generally expressed in decibels and is defined as 101g (maximum power of the side lobe/maximum power of the main lobe). For example, the ratio of the maximum power of the side lobe to the maximum power of the main lobe is 0.01, and the side lobe level is -20dB.
Polarization mode The polarization forms of electromagnetic wave can be divided into linear polarization wave and circular polarization wave. Linear polarization wave can also be divided into horizontal polarization wave and vertical polarization wave. Circular polarization wave can be divided into left-handed and right-handed circular polarization wave according to the rotation direction of electric field.
VSWR Voltage standing wave ratio (VSWR) is used to describe the matching performance of ports. The same performance can also be expressed by echo loss. These two indicators are defined as follows.
