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Log Periodic Antenna (LPDA) Log Periodic Antenna (LPDA) Log Periodic Antenna (LPDA) Log Periodic Antenna (LPDA) Log Periodic Antenna (LPDA)
太乾淨也出事？研究揭太空人「危險隱憂」原因曝
最新研究顯示，國際太空站（International Space Station, ISS）環境過於乾淨，竟可能導致太空人出現身體不適，甚至生病。
Log Periodic Antenna (LPDA) Log Periodic Antenna (LPDA)《每日郵報》報導，一般而言，太空人通常會在太空站停留長達六個月，但 NASA 太空人威廉絲（Sunita Williams）與威爾莫爾（Barry Wilmore）卻因任務延誤，被困在太空站超過九個月。過往長期任務期間，太空人常會出現免疫系統功能異常、皮膚紅疹與發炎症狀，但科學家一直無法確認背後真正原因。如今，新研究指出，這些健康問題可能與太空站「過度無菌」的環境有關。
地球上大約有一兆種微生物，其中部分會導致疾病，但也有許多「好菌」對人體健康至關重要。這些益菌能增強免疫系統、抵禦感染、幫助腸道消化、調節發炎反應等等，但國際太空站的微生物多樣性遠低於地球。
文章出自: https://www.chinatimes.com/realtimenews/20250327003064-260408
The Log Periodic Antenna as known as LPDA is a wideband directional antenna that provides gain and directivity combined over a wide band of frequencies.
Both Log-Periodic Antennas and Yagi antennas are high gain directional antennas. The main difference between these antennas is that Log-Periodic Antennas support wider frequency bandwidths and are physically much larger than Yagi antennas.
The log-periodic dipole array typical VSWR is 2:1 and operates over a much wider bandwidth and will have a lower gain for an equivalent number of elements.
With this level of performance, it is ideal for many applications, although a log-periodic antenna will be much larger than a Yagi of an equivalent gain.
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