| Summary: | 碩士 === 元智大學 === 通訊工程學系 === 102 === In this thesis, we investigate the antenna of two-way radios. Different countries and different two-way radios users use different frequency band of radio waves to carry the message they expecting to deliver. If we want to design an exclusive antenna for all of them, it may be a trouble and also inefficient, so we want to design a multi-band antenna for multiple applications.
The antennas, two-way radios using are helical antennas and whip antennas. In this thesis, we investigate the way to design an antenna based on a normal-mode helical antenna, then by using the matching circuit to make the VHF frequency band can be used. Make sure the antennas we designing can perform like the commercially available antennas. To implement a tri-band antenna, we first change the pitches of the helical antenna to achieve a multi-pitches antenna. After that, we use matching circuit to match the antenna for three bands. The material we used here to implement multi-pitches antennas is enamel insulated copper wire, and used the FR-4 substrate to achieve matching circuit. Finally, we use the Network Analyzer to measure the finished antenna to confirm the antenna performance.
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