The horn antenna is a structure consisting of a radio waveguide and a metal horn. They have a wide scope, are used in devices of measuring equipment and as an independent device.
What is it
A horn antenna is a device that consists of an open end waveguide and a radiator. In shape, such antennas are H-sectoral, E-sectoral, conical and pyramidal. Antennas are broadband, they are characterized by a small level of petals. The horn design with reinforcement is simple. The amplifier allows it to be small. For example, installing mirrors or lenses aligns the phase of the wave and positively affects the dimensions of the device.
The antenna looks like a bell with a waveguide attached to it. The main disadvantage of the speaker 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 shout 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. Most often, such devices are used as a mirror irradiator or for the maintenance of microwave links.
Features
The horn antenna pattern is the angular distribution of the power or energy flux density per unit angle. Definition means that the device is broadband, has a supply line and a small level of the back lobes of the diagram. In order to receive highly directed radiation, it is necessary to make the speaker long. This is not very practical and is considered a disadvantage of this device.
One of the most modernized types of antennas is horn-parabolic. Their main feature and advantage are low side lobes, which are combined with a narrow radiation pattern. On the other hand, horn-parabolic devices are dimensional and heavy. One example of this type is the antenna installed on the Mir space station.
According to 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 the mobile device, therefore it is recommended to protect the phone casing with a case.
Types
There are several types of horn antennas:
- pyramidal (made in the form of a pyramid of a tetrahedron with a rectangular cross section, it is used most often);
- sectoral (has a mouthpiece with the extension H or E);
- conical (made in the form of a cone with a circular cross section, emits waves of circular polarization);
- corrugated (horn with a wide passband, a small level of side lobes, used for radio telescopes, parabolic and satellite antennas);
- 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 us to study their principle of operation, to calculate radiation patterns and antenna gain at a specific frequency.
How does it work
The horn measuring antennas rotate around their own axis 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 the electromagnetic waves, whose main task is to transmit horn waves. In order to remove the directivity characteristic, it is deployed. Then the readings are taken from the device. The antenna is rotated around its axis and fix all the changed data. Apply it to receive radio waves and microwave radiation. The device has huge advantages over wire units, as it is able to receive a large amount of signal.
Where is used
The horn antenna is used as 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. Amplified units are often used for measurements. Apply the antenna as a mirror or radiation irradiator.
The inner surface of the horn can be smooth, corrugated, and the generatrix can have a smooth or curved line. Various modifications of these radiating 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 aperture.
Settings
The horn-parabolic antenna is tuned in the waveguide using diagrams or pins. If necessary, then 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 with an aperture. The larger the speaker at the antenna, the more waves it will receive. Reinforcement is easy to achieve by increasing the size of the unit. Its advantages include broadband, simplicity of design, excellent repeatability. The disadvantages are that when creating one antenna, a large amount of consumables is required.
To make a pyramidal antenna with your own hands, it is recommended to use inexpensive materials, such as galvanizing, strong cardboard, plywood in combination with metal foil. It is permissible to calculate the parameters of the 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 internal walls of the horn and waveguide should be smooth, and the bell should be rigid on the outside.