Venus: Where has all the water gone?
Conditions on the surface of venus are reviewed and evidence for the existence of a hydrosphere assessed. Escape mechanisms are examined and found to be insufficient to explain the presumed absence of liquid water on venus. The consequences of a hot, acidic hydrosphere are explored as is marginal evidence for biological activity.
Origin and evolution of atmospheres and oceans
In recent years it has become evident that the atmosphere and oceans have been produced by the outgassing of volatile materials from the earth's interior, principally from volcanoes. In 1950 W. W. Rubey presented geological evidence indicating that sea water has progressively accumulated in this way. At about the same time, Harrison Brown pointed out that the very low abundances of the noble gases in the earth's atmosphere constituted compelling evidence that at least the atmospheric oxygen and nitrogen were almost entirely of secondary origin, having been outgassed, possibly in different chemical form.
Integrated two-beam antenna array featuring dual-circular polarization
A concept of an integrated antenna array featuring two independent beams and dual circular polarization has been described. The antenna array consists of two radiating elements which are excited at two orthogonally placed feeding ports with the use of four appropriately connected 3-dB/90° directional couplers. Therefore, such an array generates two symmetrically located beams having right-handed circular polarization (RHCP) and identical two beams having left-handed circular polarization (LHCP). The presented concept has been verified by the design and measurements of an antenna array operating at 2.4 GHz frequency range.