The Principle And Characteristics Of Horn Antenna

- Dec 14 2017 - The radiation field of the horn antenna can be calculated by the Huygens principle from the mouth field. The mouth surface is determined by the size of the speaker's mouth surface and the propagation wave type. The geometric diffraction theory can be used to calculate the influence of the wall of the horn on the radiation, so that the calculated direction and the measured value are in good agreement with the far sidelobe. Its radiation characteristics are determined by the size and field distribution of the mouth, and the impedance is determined by the neck of the horn (the discontinuity at the beginning of the beginning) and the reflexes of the mouth.  When the horn length, if the horn angle increases, is two times the size and aperture phase difference also increased, but did not gain and aperture size increased, and there is a gain for the maximum aperture size, with this size is called the best horn horn.
The conical horn and the pyramid horn propagate spherical waves, and the cylindrical waves propagate in a fan-shaped horn with an open surface (E or H). The surface field of the bell mouth is a field with two square phase differences, and the size of the two square phase difference is related to the length of the horn and the size of the mouth surface.
In order to expand the frequency band of the horn, it is necessary to reduce the reflection at the neck and the mouth.  When the size of the mouth is increased, the reflection decreases. In addition, the transition section of the waveguide and the horn is made as smooth as possible, and the reflection of the part can be reduced. As the size of the horn near the position is still small, the high order mode can not be transmitted, and the single mode is generally transmitted. In order to control the radiation pattern, sometimes the multimode field distribution is needed on the surface of the mouth. At this time, a high order mode device should be introduced into the appropriate position of the horn. The horn is called a multimode horn, which can be used as a monopulse radar or an efficient antenna feed. Because of the phase velocity mode in the loudspeaker in the different frequency band, multi-mode horn horn is narrower than the conventional.