News
Antenna Direction Diagram - How to see the
antenna direction diagram?
Estimated 15minutes to finish reading
Antenna direction map, also known as
radiation direction map or far field direction map, is to describe the antenna
radiation characteristics (such as field strength amplitude, phase,
polarization) and the relationship between the space angle of the graph. It is
an important tool to measure the performance of antenna. By observing the
antenna direction diagram, we can understand the parameters and performance
characteristics of the antenna. The following is how to understand and view the antenna direction diagram of some key points:
First, the basic concept of antenna
direction diagram
- Definition: antenna direction map refers
to a certain distance from the antenna (far-field conditions), the relative
field strength of the radiated field (normalized modulus) with the direction of
change of the graph.
- Representation: Usually represented by
the power direction graph or field strength direction graph, but also used to
describe the phase or polarization direction graph.
- Graph type: the complete direction map is
a three-dimensional space graph, but in practice, usually only focus on the two
main planes (such as horizontal and vertical plane) on the direction map,
called plane direction map.
Second, how to view the antenna direction
graph
1. Identify the type of graph:
o Three-dimensional directional diagram:
with the antenna phase center as the center of the sphere, the radiation
characteristics are measured point by point on a sphere with a sufficiently
large radius to be plotted. Three-dimensional directional diagrams can fully
demonstrate the radiation characteristics of the antenna, but are more complex
to draw and view.
o two-dimensional directional map: from the
three-dimensional directional map to take a certain profile (such as horizontal
or vertical plane) to get the graphics. Two-dimensional direction diagram is
simple and clear, easy to quickly understand the radiation characteristics of
the antenna. 2.
2. Observe the key parameters:
o Main flap: the radiating flap that
contains the desired direction of maximum radiation, also known as the main
flap of the antenna or antenna beam. The width of the main flap is a physical
quantity that measures the sharpness of the largest radiating region of the
antenna.
o Auxiliary flap: The flap outside the main
flap is called the secondary flap or side flap. Vice valve level is the closest
to the main valve and the level of the highest level of the first side of the
level of the valve.
o before and after the ratio: the maximum
radiation direction (forward) level and its opposite direction (backward) level
ratio.
o Direction coefficient: a measure of the
antenna in the maximum radiation direction of the concentration of the density
of the radiated power flow.
3. Analyze the radiation characteristics:
o Directionality: the ability of the
antenna to radiate electromagnetic waves in a certain direction. For receiving
antenna, directionality indicates that the antenna has different reception
capabilities for electromagnetic waves coming from different directions.
o Gain: antenna gain is a quantitative
index of directionality, indicating the ability of the antenna to send and
receive signals in a certain direction. Gain is closely related to the antenna
direction map, the narrower the main flap, the smaller the secondary flap, the
higher the gain.
4. Judge the antenna type:
o Omni-directional antenna: It shows 360° uniform radiation in the horizontal directional map, no
directionality.
o Directional antenna: in the horizontal
direction graph for a certain angle range radiation, with directionality.
Precautions in practical application
- When viewing the antenna direction map,
need to pay attention to the scale and unit of the graph to ensure accurate
understanding of the radiation characteristics of the antenna.
- Different types of antennas have
different directional characteristics, need to choose the appropriate antenna
type according to the actual application scene and demand.
- In the communication system, the
antenna's directional map and gain is one of the key factors affecting the
communication quality and coverage, so it needs to be measured and debugged
accurately.
Antenna Radiation
Radiation is one of the basic functions of
an antenna as an electromagnetic wave transmitting or receiving device. The
following is a detailed analysis of antenna radiation:
I. Definition and principle
- Definition: antenna radiation refers to
the antenna under specific conditions will be converted into electromagnetic
waves and electromagnetic waves to the space, or from the space to receive
electromagnetic waves and convert them into electrical signals. Principle: when
the current in the antenna is converted into electromagnetic waves, the antenna
will be converted into electrical signals.
- Principle: When the current in the
antenna changes with time, it will generate a changing electromagnetic field
around the antenna, which in turn forms electromagnetic waves and radiates them
into space. Similarly, when the antenna receives the electromagnetic wave in
space, the electromagnetic wave will generate an induced current in the
antenna, which will be received and converted into an electrical signal.
Second, radiation characteristics
1. directionality:
o antenna radiation has a certain
directionality, that is, in different directions on the intensity of
electromagnetic waves radiated or received is different. Directionality is
usually expressed by the antenna direction map, the direction map describes the
antenna in different directions on the radiation or reception performance.
o The main flap of the antenna directional
map is the flap that contains the largest radiation direction, and its width
(main flap width) is an important parameter to measure the directionality of
the antenna. The narrower the main petal, the better the directionality, the
farther the action distance, the stronger the anti-interference ability.
2. polarization:
o antenna radiation of electromagnetic
waves with polarization characteristics, that is, the electromagnetic wave
electric field vector orientation in space and the law of change with time.
Common polarization mode has horizontal polarization, vertical polarization and
circular polarization.
3. gain:
o Antenna gain is a physical quantity that
measures the ability of an antenna to send and receive signals in a certain
direction. The greater the gain, said the antenna in the direction of the
radiation or reception performance is better. Gain is closely related to
antenna directionality, but also takes into account factors such as antenna
loss.
Radiation resistance
- Definition: Radiation resistance
(Radiation Resistance) is the equivalent resistance corresponding to the power
consumed by the antenna when radiating electromagnetic waves. It is a key
parameter, closely related to the efficiency of the antenna.
- Characteristics:
o Radiation Resistance is caused by the
radiation of electromagnetic waves from the antenna and corresponds to the Loss
Resistance. Loss Resistance typically causes the antenna temperature to rise,
while Radiation Resistance converts energy into electromagnetic wave radiation.
o Radiation Resistance and Loss Resistance
add up to the total resistance of the antenna (Electrical Resistance). The
Radiation Resistance is determined by the geometry of the antenna, while the
Loss Resistance depends primarily on the material of the antenna.
o Higher radiation resistance means that
less power is converted to heat and the antenna is more efficient. On the
contrary, lower radiation resistance leads to more power loss inside the
antenna and lower efficiency.
Four, the influence of factors
- Antenna structure: antenna shape, size,
material and other factors will affect its radiation characteristics. For
example, different types of antennas (such as line antenna, surface antenna,
slit antenna, etc.) have different radiation direction and polarization
characteristics.
- Operating frequency: the operating
frequency of the antenna will also affect its radiation characteristics. With
the change of frequency, the antenna's radiation direction map, polarization
characteristics, etc. will change.
- Environmental factors: the environment
where the antenna is located (such as ground reflection, other objects
blocking, etc.) will also have an impact on its radiation characteristics.
V. Application and optimization
- Application: antenna radiation is widely
used in wireless communication, radio and television, radar detection and other
fields. Through reasonable design and optimization of antenna radiation
characteristics, it can improve the communication quality, expand the coverage,
enhance the anti-jamming ability and so on.
- Optimization: In order to optimize the
antenna radiation characteristics, various measures can be taken. For example,
choosing suitable antenna type and size, adjusting antenna installation
position and angle, adopting special material and technology, etc.. In
addition, antenna radiation characteristics can also be verified and optimized
by methods such as simulation analysis and experimental testing.
