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Scratching the surface
Researchers in India have incorporated Barker non-stationary excitation and Hilbert transform based matched filtering for detection of subsurface features in glass fiber-reinforced plastic (GFRP). This pulse compression approach is less affected by random noise and variations in surface emissivity. The method is intended to help detect manufacturing defects in GFRP materials, a problem that has limited the use of these lightweight, stiff and corrosion resistant materials.
In the balance
A frequency-voltage converter circuit for alternating current electrogravimetric measurement based on quartz crystal microbalance oscillators is presented in work from France and Spain. The design improves the sensitivity (19.4mV Hz-1) and bandwidth (1mHz – 1KHz) over previous systems, and experimental results show its reliability. The team believe it will allow development of new applications in the field of electrochemistry.
An efficient rectenna with vertical ground-walls for RF energy harvesting is proposed in work from Korea. The rectenna consists of a broadband dipole antenna and the rectangular ground plane with two vertical ground-walls. The walls suppress and harvest the back-lobe of the main radiator without disturbing its electrical performance. This significantly reduces the back-lobe and harvests 1.74% of the original input power for use as a supplementary DC energy source.
A simple and efficient rectenna design has been presented by researchers in Korea. By using the vertical metallic walls on the ground plane, the proposed rectenna can harvest high level RF energy directly from the radiators, providing a supplementary DC source for communication systems.
Researchers in China have designed an antenna that offers a wide operating band, good directional radiation and low cross-polarisation. These features may allow it to replace conventional ridged horns as sensors in an EMC/antenna chamber, or as a feed for reflector antennas for square kilometre array applications.