Based on geometrical optics theory, the re-radiation is analysed by using aperture field method.

根据几何光学理论，利用孔径场法进行了分析。

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Next the electromagnetic field on aperture was found, and then proceeded to sum up five common features of aperture field of parabolic antenna.

接着求出口径上的电磁场，进而归纳出抛物面天线口径场的四大共同特征。

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The paper introduces a novel sloted antenna which is sloted on the width side of a metallic waveguide in accordance with requirements of aperture field.

本文介绍了一种新颖的开槽天线，这种天线是在矩形金属波导的宽边金属壁上按一定的口面辐射要求开出一条连续的长槽。

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In addition to daily use as a "pan-focus" lens featuring a wide angle, fixed f8 aperture and shallow depth of field, it is compatible with manual focusing using a lever and capable of close-up shooting as close as 30 cm.

ENGADGET: Olympus E-PL5 and E-PM2: Micro Four Thirds cameras with OM-D-like focusing, performance boosts (hands-on)

Shooting wide open, using aperture f2.8 on most lenses, gives you a shallow depth of field that emphasizes the part of the images you are focused on.

CNN: photojournalists share their tricks

Stopping down, using a smaller aperture like f11, or f16, will give you a maximum depth of field, which can help to show a wider scene like devastation from a tornado.

CNN: photojournalists share their tricks