A horn antenna is a structure consisting of a radio waveguide and a metal horn. They have a wide range of applications, are used in measuring devices and as an independent device.
What is this
A horn antenna is a device that consists of an open-ended waveguide and a radiator. In shape, such antennas are H-sectoral, E-sectoral, conical and pyramidal. Antennas - broadband, they are characterized by a small level of petals. The horn design with effort is simple. The amplifier allows it to be small in size. For example, the installation of mirrors or lenses aligns the phase of the wave and has a positive effect on the dimensions of the device.
The antenna looks like a bell with a waveguide attached to it. The main disadvantage of the horn is its impressive parameters. In order to bring such an antenna into working condition, it must be located at a certain angle. That is why the horn is longer in length than in cross section. If you try to build such an antenna with a diameter of one meter, it would be several times longer in length. More oftenin total, such devices are used as a mirror irradiator or for servicing radio relay lines.
Features
The radiation pattern of a horn antenna is the angular distribution of power or energy flux density per unit angle. The definition means that the device is broadband, has a feed line and a small level of the rear lobes of the diagram. In order to obtain highly directional radiation, it is necessary to make the horn long. This is not very practical and is considered a disadvantage of this device.
One of the most advanced types of antennas is horn-parabolic. Their main feature and advantage is low sidelobes, which are combined with a narrow radiation pattern. On the other hand, horn-parabolic devices are bulky and heavy. One example of this type is the antenna installed on the Mir space station.
In terms of their properties and technical characteristics, horn devices are no different from installed receivers in mobile phones. The only difference is that the latter antennas are compact and hidden inside. However, miniature horn antennas can be damaged inside a mobile device, so it is recommended to protect the phone case with a case.
Types
There are several types of horn antennas:
- pyramidal (made in the form of a tetrahedral pyramid with a rectangular section, used most often);
- sectoral (has a horn with extension H orE);
- conical (made in the form of a cone with a circular cross section, emits waves of circular polarization);
- corrugated (wide bandwidth horn with low sidelobes, used for radio telescopes, parabolic and satellite dishes);
- horn-parabolic (combines a horn and a parabola, has a narrow radiation pattern, low level of side lobes, operates on radio relay and space stations).
The study of horn antennas allows you to study their principle of operation, calculate the radiation patterns and antenna gain at a certain frequency.
How it works
Horn measuring antennas rotate around their own axis, located perpendicular to the plane. A special detector with amplification is connected to the output of the device. If the signals are weak, a quadratic current-voltage characteristic is formed in the detector. A stationary antenna creates electromagnetic waves, the main task of which is the transmission of horn waves. In order to remove the directional characteristic, it is deployed. Then readings are taken from the device. The antenna is rotated around its axis and all the changed data is recorded. It is used to receive radio waves and radiation of microwave frequencies. The device has huge advantages over wire units, as it is able to receive a large amount of signal.
Where used
Horn antenna in useas a separate device and as an antenna for measuring devices, satellites and other equipment. The degree of radiation depends on the opening of the antenna horn. It is determined by the size of its surfaces. This device is used as an irradiator. If the design of the device is combined with a reflector, it is called a horn-parabalic. Gained units are often used for measurements. The antenna is used as a mirror or beam feed.
The inner surface of the horn can be smooth, corrugated, and the generatrix can have a smooth or curved line. Various modifications of these emitting devices are used to improve their characteristics and functionality, for example, in order to obtain an axisymmetric diagram. If it is necessary to correct the directional properties of the antenna, accelerating or decelerating lenses are installed in the opening.
Settings
The horn-parabolic antenna is tuned in the waveguide part using diagrams or pins. If necessary, such a device can be made independently. The antenna belongs to the aperture class. This means that the device, unlike the wire model, receives the signal through the aperture. The larger the horn of the antenna, the more waves it will receive. Strengthening is easy to achieve by increasing the size of the unit. Its advantages include broadband, simple design, excellent repeatability. To the disadvantages - when creating one antenna, a large amount of consumables is required.
To make a pyramid antenna with your own handsit is recommended to use inexpensive materials, such as galvanization, durable cardboard, plywood in combination with metal foil. It is permissible to calculate the parameters of a future device using a special online calculator. The energy received by the horn enters the waveguide. If you change the position of the pin, the antenna will operate in a wide range. When creating a device, keep in mind that the inner walls of the horn and waveguide must be smooth, and the bell must be rigid on the outside.
