Log Periodic Antenna

因應Covid-19變異株Omicron疫情發展，快篩試劑大量需求浮現，經濟部今天(24日)宣布，即日起在四大超商（統一、全家、萊爾富、OK）及四大零售通路（全聯、美廉社、屈臣氏、康是美）全國有販售單劑亞培家用快篩劑的門市，都可依實際需求購買，不再每人限購1劑。

經濟部指出，行政院副院長沈榮津日前協調經濟部及衛福部，採每日進貨的方式，讓亞培快篩試劑在四大超商及四大零售通路通路上架販售，讓有急需的民眾可快速方便購快篩試劑，原先規定為每人限購1劑，自實施以來，因貨源因漸充足，截至5月23日在八大通路還有約160萬劑快篩試劑可供購買。

經濟部表示，隨著近期確診數增加，對快篩試劑有大量需求，且6日起八大通路銷售範圍已擴展至全國其他縣市疫情較爲嚴重區域的門市上架販賣，加上目前八大通路貨量尚足因應，因此自即日起取消每人限購1劑的規定，讓有需要的國人隨時可買到需要的快篩劑數。

原始連結

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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