By Brink A.

Naomi Pasachoff's Marie Curie and the science of radioactivity PDF

Examines the lifetime of the Polish-born scientist who, together with her husband Pierre, was once presented a 1903 Nobel Prize for locating radium.

This present day, radar in a single shape or one other is probably going to show up in all places: on the street, on the waterfront, in an underground motor-road. via a ways the widest use of radar is made via the army and scientists. In all of those fields hundreds of thousands upon millions of radar units are at paintings. a few of them are sufficiently small to be outfitted into spectacles, others weigh 1000's of plenty.

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Those frequencies cover the fundamental frequencies of GSM and its harmonics. The individual antenna was supposed to be matched to 50 Ohms at its working frequency. A matched antenna is characterised by low SWR (Standing Wave Ratio), ideally SWR=1, see Appendix B. The antenna design resulted in a solution illustrated in Figure 28. The antenna strip is located on a glass-fibre substrate with a solid sheet of copper on the opposite side. The copper sheet acts as ground plane for the antenna; since the distance from the antenna strip to the ground plane is short the antenna is narrow banded.

L = 20 ⋅ log10 (4 ⋅ π ⋅ d λ ) ;l=attenuation in dB, d=distance in meters, λ=wavelength. 4 Sources of Error Application of the shielding material: Some shielding materials are very sensitive to their application to the shield holding board. The electrical contact between the shield material and the shield holding board must be ensured. Leaks in the cable joints in the anechoic chamber: The joints between the cables leak but the effect can sometimes be reduced by use of signal absorbing material above the joints.

On the upper side the copper is removed to form an antenna strip. The copper sheet on the upper side is also left as a frame for electrical contact to the brass frame. For the purpose of making an electrically tight shield test device, the edges of the antenna board are covered by copper soldered to the ground plane on the bottom, and to the copper frame on top of the board. An informative illustration is in Figure 30. The manufactured antenna board has got more screw holes than the illustration hint.