聯合國宣佈全球人口突破80億,下來的10億人口,有半數將出生在八個國家,而有三分之二的國家人口將減少。

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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