• 作者： 鄭伯順
• 作者服務機構： 交通部電信研究所
• 中文摘要： 微波系統於長程通信耗費較低廉，其在臺灣地區極為需要，但因通信需求量之增加，一旦未來操作頻率超過 10 GHz 時，會因降雨引起接收訊號強度之衰減而影響品質。 本文假設微波雨量衰減及降雨率為對數常態分佈，以定量估計臺彎西部地區七個主要都市之微波雨量衰減，求出當操作頻率為：11,12,14,18,20,30 及 60 GHz 時在不同跳程 (HOP) 長度之微波雨量衰減分佈，同時假設系統預留若干衰減餘裕，不同跳程長度每年會有多久之通信中斷時間產生及假設系統每年服務之平均通信中斷時問不超過0.02％時，求出不同跳程長度所應預留之衰減餘裕，發現西部地區微波系統在相同跳程長度，基隆地區需預留較多之衰減餘裕，而臺中則需較少之衰減餘裕。
• 英文摘要： Rain-induced fading is an important factorfor microwave system design at frequenciesabove 10 GHz. Microwave system offers theleast expensive long-haul facilities, and is def-initely needed in Taiwan. So we make a quan-titative estimation of microwave rain attenuationin the western area of Taiwan. The calculationis based approximately upon the observed log-normality of rain attenuation and the rain ratestatistics within the range of interest. We havecalculated the microwave rain attenuation as afunction of hop length for each of the frequen-cies：11, 12, 14, 18, 20, 30, and 60GHz. Theoutage times of the radio paths at frequenciesabove 10GHz are estimated from the distributionof rain attenuations. Assuming the averageoutage time not exceed 0.02 percent per year,we calculate the fade margin as a function ofhop length and find that for the same hop length,in the western area of Taiwan, the fade marginneeded is the most in Keelung, whereas theleast in Taichung.
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