| With the rapid development of the wireless communication system, an increasingly higher demand is required to the structure and performance of antenna in wireless devices. On the one hand, owing to their good performance, directional antennas have been widely used in electronic equipment, such as communication, radar, radio broadcasting, navigation, detection, etc. On the other hand, for some special requirements, antenna with high gain and beam scanning features are needed. However traditional beam controlled arrays, such as parabolic antenna and phased array, are either low in performance or costly in fabrication. It is imperative that high gain antenna array with new beam scanning form is proposed and researched. In this paper, based on the broadband directional antenna, three kinds of antennas, namely, microstrip antenna, magneto-electric dipole antenna, printed endfire antenna, are studied. Meanwhile, a new beam controlled high-gain antenna array with is proposed. The author’s major contributions can be summarized as follows:1. A research has been made on the broadband and multi-band technology of microstrip antenna. Firstly, through the combination of half elliptical parasitic patch with air medium, a broadband microstrip antenna with 28.1% relative impedance bandwidth is presented. Secondly, a dual-band microstrip antenna with ingenious feeding is proposed. The antenna can operate at around 13.0 GHz and 18.0 GHz and the relative impedance bandwidth is about 10.0% and 22.3%, respectively. Finally, based on the dual-band antenna, through adding an F-shape branch, a multi-band microstrip antenna is designed. The four bands are 6.9-7.3 GHz,12.4-13.2 GHz,14.3-14.8 GHz and 17.7-21.0 GHz, respectively. The antenna shows stable gain and good directional radiation performance at each band. The measured results validate the correctness of the design.2. A printed magneto-electric dipole antenna with vertical structure is proposed. The printed bowtie dipole and semi-torus act as electric dipole and magnetic dipole, respectively. In order to obtain a broadband impedance matching, a microstrip to coplanar stripline balun is employed to excite the electric dipole and magnetic dipole simultaneously. The measured results show that the impedance bandwidth for VSWR less than 2 is about 2.45-4.90 GHz. while the measured and simulated results reveal that the radiation patterns of the antenna at the high frequency band appear grating lobe. For a better radiation performance, an artificial metamaterial with high refractive index is designed. The metamaterial is composed of common material and H-shape resonator. Through adding the metamaterial to the front of the magneto-electric dipole antenna, a better radiation pattern at high frequency band and a higher gain at the whole band are achieved. The measured results display that the modified antenna can operate at 2.31-3.93 GHz and a stable gain of about 8.5+1.2 dBi is obtained. Finally, based on the modified antenna, some simulations have been made and the results reveal the good performance of the antenna, which means that the antenna has certain practical value.3. Three printed endfire antennas with broadband performance are proposed based on a study of the characteristic of Quasi-Yagi printed endfire antenna. Firstly, by employing the broadband characteristic of the microstrip to coplanar stripline transition, a printed endfire antenna measured by 24.24 mm×30 mm is presented. A relative impedance bandwidth of about 75% for VSWR less than 1.5 at S band is achieved. Meanwhile, the antenna displays good endfire radiation performance at the operating band. Secondly, based on the printed monopole, through adding the directors and reflector, a broadband antenna with endfire radiation performance is designed. Finally, by changing the structure of the directors without increasing the size of the antenna, an antenna with larger bandwidth and better radiation performance is designed and good agreements between the simulated and measured results are achieved.4. An array with new beam controlled form is proposed. Based on a circularly polarized spiral antenna, the phase difference between different elements in an array is controlled by rotating each elements with different angles and the array can switch among different beams. For verifying this theory, an array with 128 circularly polarized elements is designed and fabricated. The array is excited by a stripline power divider that has equal amplitude and phase in each output port. Meanwhile four array planes, namely sum beam array plane, difference beam array plane,10° scanning beam array plane and flat-topped beam array plane, are designed for switching among each other. By connection the power divider with the four array planes respectively, four beams can be achieved. The good agreements between the simulated and measured results validate the feasibility of the theory. Considering the performance can be obtained without using phase shifter, the antenna array will be low in cost. It is predicted that this beam controlled array will be of great applications when a rotation servo system is added to the array.
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