이종 철도무선통신장비의 통합을 위한 VHF/UHF 전력증폭기

In this paper, we propose the VHF/UHF power amplifier for integrating various wireless systems of railway communications. The proposed power amplifier can integrate several power amplifiers, which are used for FM rerun equipment of 88 to 108 ㎒, VHF hand-held radio of 146 to 174 ㎒, and train wireless protection equipment of 443 ㎒. The VHF/UHF power amplifier adopts the GaN HEMT and the negative feedback method for achieving the wide bandwidth characteristics of VHF and UHF. From measurement across the bandwidth of 30 to 500 ㎒, an output power over 20 W and power added efficiency over 40 % was obtained. An intermodulation distortion below -37.7 ㏈c was measured for 2-tone test signal. From the digital predistortion measurements, an IMD reduction over 16.2 ㏈ was obtained.