Switched ring antenna array with electronic scanning

Abstract

For operation in the frequency range of 5,1–5,9 GHz, a directional antenna device has been developed for use as part of a base station in a stationary point-to-multipoint system with a controlled beam position. The antenna device is a switched, broadband, ring antenna array with electronic scanning in the azimuthal plane. Its distinctive feature is high gain of the radiating elements, which are used as linear printed antenna arrays with parallel power supply. The required directional characteristics and matching of the emitters have been achieved in the process of parametric synthesis carried out using the CST MS program. In a given frequency range, the emitters are characterized by the following parameters: width of the main lobe of the directional pattern in the E-plane is 6,6…7,5 deg; level of the first side lobe in the E-plane is 0…–11,4 dB; width of the main lobe of the directional pattern in the H-plane is 53,2…73,4 deg; level of the first side lobe in the H-plane is –23,4…–26,4 dB; gain is 17,0…17,5 dB; the reflection coefficient at the input of the emitters does not exceed 0,2. In the horizontal plane the main lobe of the directional pattern at different frequencies is shifted by an angle of 5–10 deg relative to the normal to the radiating opening of the emitters. The reason is a microstrip distributor combined with printed antenna array emitters on a common printed circuit board. The specified offset of the main lobe of the directional pattern does not decrease the functional characteristics of the antenna device, because the difference in level in the direction of the main maximum and in the direction normal to the radiating aperture of antenna arrays does not exceed 0,5 dB. In addition, the specified offset at the given frequency is regular and has the same value for all emitters of the ring antenna array. Therefore, the angular discret and the level of overlap of the directional patterns of the neighboring emitters when scanning in the azimuthal plane remain unchanged. The results of an experimental study of a prototype antenna device have been presented. They are in good agreement with the results of computer modeling.