| Summary: | 碩士 === 義守大學 === 電子工程學系 === 101 === This thesis uses a simple concept to design a coplanar microstrip antenna for dual band operation. When the microstrip patch is reshaped into a Z, the magnetic current on PMC can contribute the radiation with the same polarization, thus antenna can operate at dual bands. And the design concept is confirmed by theoretical results, simulation and experiment, the characteristics of antenna can be obtained by investigation on parameter variations.
As the characteristics of Z-shape microstrip antenna, result shows that the distribution of electric field along the longitudinal axis is more intensive than original cosine with half wavelength. In contrast, the distribution along transversal axis still remains half wavelength. These results are consistent with the design concept, and the single-beam radiations of two modes by simulation also verify that this antenna has dual band operation. According to the result of investigation on parameter variations, the length along transversal axis can adjust the frequency spacing substantially, and the legs widths can minorly adjust this spacing. In addition, asymmetric structure of antenna can offer higher design freedom. This information does not only establish the design procedure but also enhance the efficiency.
As the analysis method, this thesis uses the cavity mode to divide Z-shape microstrip antenna into three rectangular regions, thus electromagnetic expression can be simplified. And analysis procedure is done by solving the boundary conditions and continuity of the electromagnetic fields and using the process of with moment method. Therefore, characteristics of electromagnetic waves in this antenna and resonant frequency are investigated. Theoretical, simulated and experimental results are similar with each other, these results also confirm design concept and verify simulation. In other word, the investigation on parameter variations by simulation is reliable.
This design concept is simple and straightforward, and Z-shape microstrip antenna is coplanar which is beneficial for integration with other components. This antenna can be used in two specific commercial bands after parameters adjustment, so the design procedure can be also eligible for other bands. Therefore, this design is practical with values.
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