| 摘要 |
<p>1500075 Cooled antenna INTERNATIONAL STANDARD ELECTRIC CORP 21 March 1975 [22 March 1974] 12011/75 Heading H4A A helical antenna, Fig. 1, comprises a helix element 2 which is formed by winding tubing, Fig. 4, into a helical shape, the tubing containing means for distributing heat along the length of the helix. The tubing, sealed at both ends, contains liquid (e.g. water, a ketone, an alcohol or a fluorocarbon) in equilibrium with its vapour, which liquid vapourizes at hot spots 47 (caused by high current flow) and condenses at cool regions, so distributing the heat generated by the current in the helix. The liquid returns to the hot spots either under gravity or by capillary action in a porous layer 44 on the inner surface of the tubing (e.g. a braided layer of cotton, wool, felt or fibreglass). A braided copper mesh tube may be inserted in the tubing to prevent the porous material filling the central passage (Fig. 4c, not shown). The tubing is generally aluminium or copper 42, coated on the outer surface with silver 43. The inner surface may be treated to make it porous as an alternative to introducing braids (Fig. 4d, not shown). The construction of the antenna itself is known, comprising an earthed helix 2 whose length is effectively altered by tuning element 1 making contact between the helix 2 and cylinder 4 through brushes 3 said element being driven by a motor 5. The range of frequencies of signals to be radiated is from 2-12 MHz in the “ wave mode and 10-30 MHz in the ¥ wave mode. The helix is embedded in an insulating coilform of epoxy-bonded or silicone-bonded fibreglass. A coilform in the present invention may support higher power radiation than the same coilform in a known antenna due to the internal dissipation of heat in the helix.</p> |
