短語詞組短語broad beam attenuation 寬束的衰減;寬束衰減beam attenuation coefficient 光束衰減系數(shù)primary beam attenuation 主束衰減narrow -beam attenuation 細衰減;窄束衰減;窄束減弱broad d beam attenuation 寬束的衰減beam attenuation grid 射束衰減網(wǎng)格attenuation beam 束流衰減 返回 beam attenuation