At some frequencies, it can penetrate walls.

在一些频率，它能穿透墙壁。

youdao

In a built-up area, signals bounce off buildings, trees, and at some frequencies even people.

在建筑物密集的地区，信号会被建筑物、树木反弹，某些频率甚至能被人反弹。

youdao

Then it takes some EMC measurements. After taking the EMC measurements, the system is tested at some frequencies.

最后对实施电磁兼容措施的器件测试了多个频点的电磁兼容性能。

youdao

It acts to amplify infra-red emissions at some frequencies and suppress them at others.

ECONOMIST: Solar power

Google has long been involved in public trials to prove the technology which operates at lower frequencies than some cell networks, allowing signals to be more easily transmitted through buildings and other obstacles and across longer distances can work.

WSJ: Google to Fund, Develop Wireless Networks in Emerging Markets

Some experts in the field seriously question whether it is possible to develop materials capable of perfect lensing at optical frequencies.

BBC: Last Updated: Monday, 8 March 2004, 09:03 GMT