Antenna gain
The antenna gain of an antenna indicates the amplification of the transmitted energy. This gain results from the focusing of the transmitted energy by the antenna in a horizontal and/or vertical direction (see aperture angle 2.2). An omnidirectional antenna (which only exists in theory), which emits the transmission energy uniformly in all directions, has no antenna gain (0 dBi and 0 dB) and serves as the basis for calculating the gain. With omnidirectional antennas, the transmitted energy is emitted in a radius of 360° in the horizontal axis, but less than 360° in the vertical axis. This results in an antenna gain of 2.5 dB for the antenna with article number 10926, for example.
The higher the antenna gain, the greater the range, but the smaller the aperture angle.
Radiation pattern of an antenna
The radiation pattern of an antenna, often also called beamwidth, graphically represents the directivity of an antenna. The beamwidth is the range in which at least half of the maximum radiation power is still available.
The narrower the beam width, the greater the range. The larger the aperture angle, the shorter the range.
Omnidirectional antennas
An omnidirectional antenna has a uniform radiation pattern on a horizontal plane in all directions. This means that it has a horizontal aperture angle of 360° and is used for mobile - e.g. rotating or mobile - applications due to this characteristic. Tilt stands for the displacement of the vertical aperture angle of an omnidirectional antenna in a certain direction, starting from the horizontal plane. In the picture below, for example, you can see a vertical aperture angle of 40° with a tilt of 20°, so the vertical aperture angle is shifted upwards by 20°.
Directional antennas
With a directional antenna, the radiation density is aligned in a precise spatial direction. The directional effect attenuates the reception of interfering transmitters outside the main or side lobes and increases the range in the direction of radiation. This means that the antenna only radiates in one direction and has an aperture angle of 80°, for example.
Fresnel zone
In antenna technology basics, a Fresnel zone is a spatially imagined three-dimensional ellipse between the antennas of a radio transmission link. The radius of this zone is calculated from the transmission frequency and the distance between the antennas. Ideally, there should be no objects within this zone. Objects in the Fresnel zone have a negative effect on the range. If there are too many objects in the Fresnel zone, no radio connection can be established. Example: At 2.4 GHz (DATAEAGLE with Bluetooth) and a distance of the antennas over a radio transmission distance of 100m, the maximum radius of the Fresnel zone is approx. 2m. At a frequency of 2.4 GHz, the antenna should be mounted at a height of at least 4 m in order to create optimum conditions for a long range.
Polarization
Polarization describes the direction in which the oscillations of the electric field propagate. A distinction is made between horizontal and vertical linear polarization (VP) and right-hand circular polarization (RHCP). The transmitting and receiving antennas should have the same polarization. The use of unequally polarized antennas can lead to losses or no radio connection can be established. We use antennas with vertical linear polarization (VP) and clockwise circular polarization (RHCP). An RHCP antenna is suitable when using directional antennas with line of sight. We recommend VP antennas for all other applications.
Transmitted power
The transmission power, or EIRP (equivalent isotropically radiated power) for short, is the actual radiated power, which is made up of the transmission power of the source (in our case the DATAEAGLE) minus all attenuation losses such as those caused by cables, adapters, lightning protection, plus the antenna gain. The equivalent transmission power is regulated by law. The maximum permitted values vary depending on the frequency band (e.g. 100 mW / 20 dBm for Bluetooth 2.4 GHz).
Link budget
Link budget (power transfer balance) is a unit of measurement for the difference between transmission power (EIRP) and receiver sensitivity. The link budget is used to estimate the range of a signal. The factors that must be taken into account for estimation are, for example
- Transmitting power
- antenna gain
- Receiver sensitivity
- Free space attenuation
- Cable attenuation
Reflection
Reflections are interference factors that occur when radio signals encounter obstacles. Reflection can lead to interference. This means that the antenna signal is superimposed by the reflection.
Use cases - how it works in industry
Whether conveyor technology for cranes, connecting systems in sewage treatment plants or driverless transport systems: Wireless is always sexy. Especially in industry, stable connections are the be-all and end-all. Intelligent radio is the reliable partner for everything that counts.
