High‐gain ultra‐wideband quasi‐conical beam Fabry‐Perot antenna based on beam switching

Abstract

To solve the contradiction between the high gain and wide coverage, the concept of the quasi-conical beam is proposed by using the high-gain pencil beam electrically switching along a cone to make full use of time redundancy. In a periphery-fed Fabry-Perot (FP)-type multi-beam antenna, the electrically switching is used to activate the different port corresponding to the different beam for the beam switching in the azimuthal plane, and the varying frequency is used for the continuous scanning in the elevation plane. Different from the lens or matrix multi-beam arrays, in this scheme, the FP cavity serves as both the beamforming network and the radiator to produce the multi-beam. Around eight planar antipodal Fermi-tapered slot antennas are placed around the FP cavity between the partially reflective surface and the metal ground plane as the primary feeds. The simulation and measurement results show that a relative impedance bandwidth of 53.3% with reflection coefficients below −10 dB from 11 to 19 GHz is obtained and the peak gain is 17.1 dBi at the central frequency of 15 GHz. The results also show that a high-gain beam scanning from 22° to 59° in the elevation plane is achieved and the peak gains are between 16 dBi and 20 dBi. In addition, when the electrically switching of the beam is along a cone, the proposed antenna may form quasi-conical beam. And in some applications, it may replace the conventional conical beam antenna with the advantages of wide coverage and high gain.