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Conclusion:In single-fed microstrip antennas the narrow CPBW arises mainly from the difficulty of maintaining the proper excitation conditions and hence polarisation purity over a wide bandwidth. In this Letter, it has been made clear that the trade-off between good axial ratio and impedance bandwidth usually limits the designer in single-fed CP schemes, where techniques for achieving wideband polarisation techniques as well as wideband impedance features are important.In summary, a new CP single-fed dual-band microstrip antenna has been described. The new geometry of the microstrip patch antenna has proven to be a flexible and CP dual-band element. This is particularly important for mobile communications systems where small size, light weight, low profiie and low cost are often demanded in portable or pocket-sized equipment and vehicles. It is especially relevant when a flush-mounted or built-in antenna is required. It can also be applied to satellite systems where two channels are needed to receiveitransmit the telecommand and telemetry signals (GPS receivers) or in a hand-held message communication terminal (HCMT).

Electrodeposition experiments conducted in a thin-layer horizontal cell containing a nonbinary aqueous electrolyte prepared with cupric sulfate and sodium sulfate gave rise to fingerlike deposits, a novel and unexpected growth mode in this context. Both the leading instability from which fingers emerge and some distinctive features of their steady evolution are interpreted in terms of a simple model based on the existing theory of fingering in fluids. [S0031-9007(96)

Dynamic morphological transitions in thin-layer electrodeposits obtained from copper sulphate solutions have been studied. The chemical composition of the electrodeposits indicates that they appear as a consequence of the competition between copper and cuprous oxide formation. In addition, the Ohmic control of the process is verified at initial stages of the deposit growth. At higher deposit developments, gravity-induced convection currents play a role in the control of the whole process and affect the position of these transitions.

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