A novel sum and difference (SD) conical beam-scanning reflector antenna is proposed in this paper. The reflector surface, illuminated by two omnidirectional horns, is a body of revolution obtained by revolving the generating parabola about a symmetry axis. The horns stacked along the symmetry axis of the reflector are fed by a nest coaxial waveguide. Teflon lens is used to improve the side lobe levels and reflection coefficients of the feed horns. By tilting the generating parabola and using the offset feeding method, two conical beams, with different beam pointing angles, were generated. A compact feed network was also designed to feed the two horns, which includes two rectangular TE10 mode-to-coaxial TEM mode transitions and a Magic-T to implement SD beams. The scanning performance of conical beams can be achieved by mechanically moving the feed antennas along the symmetry axis and taking full advantage of offset focus characteristic of the parabolic reflector. The error in angle measurement was also discussed. The SD conical beam-scanning antenna was formed by a parabolic dish with a radius of 18 λ operating at 24 GHz. The proposed antenna was designed, simulated, and fabricated. The measured results show that the difference beam null-depth is −25 dB and the sum beam gain is 15 dBi at 40°. The sum beam gain varies by less than 1.5 dB across the scan coverage from 30.8° to 45.2°. The measured results are found to be in good agreement with the simulated ones. INDEX TERMS Reflector antenna, conical beam, magic-T, sum and difference beams I. INTRODUCTION Of late, much attention has been paid to conical beam antennas, because they are good candidates for satellite communication, target detection, tracking or guiding system, and so on. Conical beam antennas are superior to phased array antennas and omnidirectional antennas in TACAN-tactical air navigation system, vehicles communication, etc., because of their low cost and better performance. Satcom on the Move (SOTM) system needs high-gain and wide-beam coverage to obtain good quality communication [1]. The conical beam-scanning antennas with sum and difference beams for tracking capability can give better performance-to-cost ratio. Different from the traditional pencil beam monopulse antennas [2]-[4], the beam coverage of conical beam antenna is a ring area rather than a spot area. Therefore, conical beam antennas have intrinsic advantage of being wide beam coverage that is very important in many applications. Consequently, unlike the pencil beam the gain reaches 15dBi
In this article, a concise equivalent circuit model for top‐loaded folded monopole antenna (TLFMA) of low profile is presented. The TLFMA has one driven post and one shorting post, loaded with a circular conducting plate on the top, which can achieve a very low profile with a good radiation resistance. The equivalent circuit consists of two models, which are transmission‐line mode and antenna mode. The impedance of TLFMMA can be easily get from this equivalent circuit model. The accuracy of the presented equivalent circuit model has been verified by the simulation and measurement results.
Modern industry is faced with “four heights” -- high temperature, high pressure, high stress and high speed. Among them, the importance of nondestructive testing is becoming more and more prominent with the process of industrial modernization [1]. Enterprises and society have more and more demanding requirements on product quality and equipment function. How to solve and eliminate this problem has become an important opportunity for the development of NDT industry. The current hot artificial intelligence technology undoubtedly brings the method for NDT, the combination of the two is bound to produce huge energy to promote its progress in the electric power industry [2]. Based on this, this paper explores the phased array detection technology and its application progress in the power industry under the background of artificial intelligence [3].
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.
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