What Is an Antenna Radiation Pattern?

The antenna radiation pattern refers to the graph of the relative field strength (normalized mode value) of the radiated field as a function of direction at a certain distance from the antenna. It is a graphical description method of the antenna's radiation characteristics. Antenna radiation pattern is also called antenna pattern and far-field pattern.

The antenna radiation pattern refers to the graph of the relative field strength (normalized mode value) of the radiated field as a function of direction at a certain distance from the antenna. It is a graphical description method of the antenna radiation characteristics. Various parameters of the antenna. It is usually expressed by two mutually perpendicular plane patterns in the direction of maximum radiation of the antenna.

1. A line antenna installed on the ground generally uses two mutually perpendicular planes to indicate its pattern. That is, a horizontal plane pattern and a vertical plane pattern.

2. UHF antennas are usually represented by two planes parallel to the field vector, that is, the E-plane pattern and the H-plane pattern.

3. According to the choice of coordinates, it can be divided into rectangular coordinate pattern, polar coordinate pattern, spherical coordinate pattern and so on.

4. Different objects: field strength pattern, power pattern, phase pattern and polarization pattern

This mainly involves field strength and power patterns, and phase and polarization patterns are used in special applications. For example, in antenna near-field measurement, both the field strength pattern and its phase pattern need to be measured.

The antenna radiation pattern can be drawn in two ways: one is to obtain the radiation field in the far area of the antenna through theoretical analysis to obtain the pattern function, and the pattern is calculated and plotted; the other is to experimentally measure the antenna pattern data And draw the direction diagram.

The antenna pattern is generally petal-shaped and is called a lobe or beam. The lobe containing the maximum radiation direction is called the main lobe, and the other is called the side lobe or side lobe, and is divided into the first side lobe and the second side lobe. The beam opposite to the main lobe direction is called the back lobe

The antenna radiation pattern contains various parameters of the antenna, including:

1. Half power lobe width (HPBW, half power beamwidth), 3dB lobe width: In the plane containing the main lobe, the angle between the two directions where the radiated power is half the maximum

2 Main lobe width: It is a physical quantity that measures the sharpness of the antenna's maximum radiation area. The width between the two half power points of the main lobe of the antenna pattern is usually taken.

3 First zero lobe width (FNBW): The angle between the first zeros on both sides of the main lobe in the plane containing the main lobe.

4. Sidelobe level: refers to the level of the first sidelobe closest to the main lobe and the highest level, usually expressed in decibels.

5. Front-to-back ratio: The ratio of the maximum radiation direction (forward) level to the opposite direction (backward) level, usually in decibels.

6. Direction coefficient: The ratio of the radiated power flow density of the antenna in the maximum radiation direction to the ideal non-directional antenna of the same radiated power at the same distance at a certain distance from the antenna. ^[1]