| Planar printed antenna has become more and more important in the antenna devel-opment, because of its low profile, compact structure, light weight, easy fabrication and integration. However, there are several problems when the printed antennas that have dif-ferent radiation pattern are used in different practical applications. To solve the existing problems of the printed frequency scanning antennas, dual-beam antennas and coni-cal-beam antennas, this dissertation focuses on the theoretical analysis, practical design and verification of the solutions. The main innovations in this dissertation are as follows:1. Low-loss printed frequency beam-scanning antenna with flat high gain and low side lobe levels:According to the large loss in the printed transmission lines at high frequencies with large electric length, the antenna gains of the printed frequency scanning antennas are usually low. A frequency scanning slot antenna based on the even-mode bilat-eral broadside-coupled suspended microstrip line (BSML) has been proposed. The antenna exhibits good performances of high frequency sensitivity, low loss, high gain and low side lobe level (SLL). The printed antenna achieves the beam scanning of -27.5°to +46° in the whole frequency range from 8.9GHz to 10.6GHz. The maximum measure gain is 15.5dBi with the variation of less than 2.5dB in the operating band. The SLLs at most of the fre-quencies are near 20dB. The slow-wave structures for phase shifting, power dividers and radiating slots in the printed antenna can be designed independently, which provides a new solution to the low-loss printed frequency scanning antenna array.2. High-gain dual-beam antenna array and conical-beam antenna array with large beam-pointing angle exploiting grating lobes:The beam-pointing angle of the two kinds of antennas is getting smaller with the increase of the array aperture, in which the aperture efficiency is also decreased. To solve this problem, arrays with conical-beam an-tenna elements exploiting grating lobes are proposed to achieve high gain and fixed large beam-pointing angle. In practical measured designs, the dual-beam rectangular array an-tenna presents two symmetric radiation beams, directed at ±49.4° with 16.6dBi gain. The conical-beam circular array antenna exhibits the maximum radiation gain of 9dBi at 48° elevation. The detailed array analysis and design principle are given.3. Wide-band circular patch conical-beam antenna with multi-point feed tech-nique:To solve the narrow bandwidth problem in conical-beam circular patch antenna, a wide-band circular patch antenna with the loop-fed technique has been proposed. Based on the combination of the two magnetically coupled resonances of the feeding loop and the circular patch, the measured antenna achieves a bandwidth of 65.3% with 0.13λ0 heights. The antenna provides stable conical radiation patterns in band. The design concept, theo-retical analysis, parametric study and design principle have been given in detail.4. Common aperture wide-band circular patch antenna with reconfigurable conical beam and pencil beam:A wide-band circular patch antenna has been proposed using different sets of feeding loops to simplify the design complexity in reconfigurable antennas. The common aperture antenna can radiate conical beam and pencil beam with different excitations. The measured impedance bandwidth for the pencil beam is 27.2% and for the conical beam is 45.9%. The overlapped bandwidth is 24%. The antenna is with full PCB fabrication in a simple structure. The design concept, theoretical analysis, para-metric study and design principle have been given in detail.
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