L \ X-band Dual-frequency Aperture Array Antenna Research

In recent years, dual-band microstrip antenna and array have taken more and more attraction. There are many publications on dual-band microstrip antenna element already, with many of these designs broadly used in wireless communication systems. However, the antennas with big Frequency Ratio (FR) range, good dual-frequency characteristics and compact structure will still be the point in the future research. On the other hand, the research on dual-band arrays, especially with big frequency ratio, is under developing up to now. In practice, such kinds of dual-band arrays are very important for Radar, wireless communication system and so on.In this thesis, the research will focus on the dual-band characteristic of microstrip antenna and array. A new L\X dual-frequency shared-aperture microstrip antenna array is proposed. The array has big frequency ratio (about 1:8) and good dual-band characteristics. Two kinds of novel dual-band microstrip antenna models are presented, with big FR range and good bandwidth property.Chapter 1 and chapter 2 are focused on the development state of dual-band antenna and array, fundamental concepts and principles on antenna and array design and so on, which is the basis of the later research and design.In chapter 3, more attentions are paid to dual-band antenna element design. Two novel dual-band antenna elements are realized by adding load to the feed structure, which is different from the normal techniques. These novel models have good dual-band characteristics, bandwidth property andflexible FR range.Chapter4 and 5 are the stress of the thesis. The research and design on dual-band microstrip array are introduced. According to the requirements of array design, the shared-aperture structure is chosen. The combination of microstrip dipole antenna and slot antenna array is used in the array design, with the dipole antenna in the upper layer. This structure is good at avoiding the interference between the two-band sub-arrays. The design prototype is optimized, manufactured and measured. According to the results from the simulation and measurement, it is verified that such a design has good dual-band characteristics.In chapter 6, the summary of the whole research is given, and the future researches are also proposed.