想要跟牠比?只能叫你阿嬤來囉!美國加州科學院(California Academy of Sciences)的斯坦哈特水族館(Steinhart Aquarium)中,有一隻年齡高達90歲澳洲肺魚「瑪土撒拉(Methuselah)」。牠年紀奇高,是今年世界上現存最老的觀賞魚,可個性溫和可愛,還會靠向飼育員的手討摸。
據外媒報導,這隻90歲的澳洲肺魚「瑪土撒拉」,名字與《聖經》中享嵩壽969歲的最長壽者相同,牠全長1.2公尺、重達18.1公斤,目前研判為雌性。澳洲肺魚,又稱昆士蘭肺魚,一般只生活在澳大利亞昆士蘭州,為同時擁有肺和腮的原始物種,被科學家認定是魚類及兩棲動物進化過程中的重要角色。
瑪土撒拉性格相當溫順,當人類擺出食物,牠就會游至身旁覓食,也非常享受被抓搔背部的感覺,甚至會像狗狗一樣將頭靠在人類的手掌上撒嬌。生物學家艾倫(Allan Jan)表示:「瑪土撒拉性格溫和、文靜,像是隻水中的小狗狗,但若受到驚嚇,就會突然變得很有活力。」
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.
In terms of its specification, a typical log periodic antenna might provide between 3 and 6 dB gain over dipole for a bandwidth of 2:1 while retaining a VSWR level of better than 1.3:1. 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.
EMC/EMI pre-compliance test antenna.
Very high gain over the full frequency range.
Meets latest EMC standards up to 7GHz.
Suitable even for immunity measurements
此外,也有另一條澳洲肺魚「爺爺(Granddad)」,在2017年時成為世界上最長壽的觀賞魚,最後以95歲高齡辭世於芝加哥謝德水族館(Shedd Aquarium)。(編輯:李惠婷)
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