Log Periodic Antenna

明天天氣如何?

明天降雨、降溫情況相對明顯，東北部白天預估都在20度以下，中部高溫19-21度，南部則在22-24度左右，中北部夜晚到清晨的低溫在17度左右，局部沿海空曠地區、近山平地可再降2-3度，配合較大的風力，感受較濕冷，外出要留意保暖、攜帶雨具。

預計週二下半天華南部分的雲系逐漸減少，台灣附近的風向也將轉偏東風，各地溫度回升，北部降雨緩和，不過南海仍然有雲系通過中南部、東部，週二到週四仍有些局部的短暫雨，南方雲系中有些小尺度的對流系統發展，南部地區可能受到影響，有短暫雷雨的機會，天氣仍不太穩定。

週四到下個週末天氣系統強度較弱，台灣處於微弱的風向交界環境，大氣有不穩定的條件，而且也有些水氣存在，台灣上空除了午後山區有些熱對流發展外，附近也有雲系生成，可能移入帶來短暫雨或由晴轉陰的天氣變化，天候變動的狀況較多。

以上氣象由天氣風險/柯聿寧提供

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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