Study And Design Of The BJT Active Integrated Antenna

Based on the work of the formers, this paper gives emphasis on the research of some problems about the design method and the harmonics suppression of the active integrated antenna (AIA).Firstly, the microstrip antenna has complex input impedance, so it is important information for designing oscillator type active integrated antennas. The available commercial software can't simulate the antenna and active circuit in the same simulator environment. For convenience of AIA design, the AIA design method based on the input impedance wide-band model of patch antenna is used in this paper. The input impedance wide-band model can be calculated from the antenna's cavity model. The input impedance model is used to substitute the microstrip antenna in harmonic simulation of nonlinear circuit, from which can get the spectrum of AIA and the voltage across the impedance model. The voltage is put on the input port of the microstrip antenna as an exciting source to calculate its radial electromagnetic fields, therefore, direction patterns and radiation powers. The experimentation results show the efficiency of the procedure.The electromagnetic interference is an important problem of a microwave system. It is caused by harmonic radiations, which come from the harmonic signals of nonlinear active element. The oscillator type AIA has the same shortage. Changing the input impedances of the antenna at the unexpected resonance frequencies can control the harmonic radiations of AIA. H-shaped antenna needs this requirement. The experimentation results show the H-shaped AIA can suppress the harmonic radiations.