| 摘要 |
<p>1374741 Aerials SAINT-GOBAIN INDUSTRIES 12 Jan 1973 [14 Jan 1972] 1784/73 Heading H4A A window pane such as a motor vehicle windscreen incorporates an aerial which comprises two aerial elements of different configurations. The said elements are connected together, and have a common feed terminal. One element is made up of two parts which are arranged with relative electrical asymmetry with respect to the other element. Both elements are tuned to the same frequency, e.g. a frequency in the range 80 to 220 mHz. In one embodiment, a windscreen la, Fig. 3, comprises a central vertical conductor 2 which extends from a terminal 4 to connect at a point 5 with an upper horizontal conductor 3. Each conductor has a length equivalent to #/2 (# = wavelength at frequency of operation) and the point 5 is offset from the centre of the conductor 3 to provide optimum feed conditions. In a second embodiment a central vertical conductor is provided with a symmetrically disposed upper horizontal member (forming a "T") and is associated with a lower asymmetrically disposed horizontal conductor, the two conductors being connected together adjacent a feed terminal (Fig. 4, not shown). In a third embodiment a T-shaped central conductor 13, 14, Fig. 5, is associated with a U-shaped conductor having two symmetrical branches 15a, 15b. Asymmetry is provided by capacitive loading of the branch 15b, a conductor 16 being disposed parallel thereto, and connected to the vehicle body. Alternatively, inductive loading may be used. In a fourth embodiment, somewhat similar to the third, asymmetry is provided by omitting the upper horizontal part of one of the branchesof the U-shaped conductor (Fig. 6, not shown). In other embodiments, also somewhat similar to the embodiment shown in Fig. 5, asymmetry is provided in the lower horizontal portions of the two branches of the U-shaped conductor, in one case by duplication of unequal portions thereof (Fig. 7, not shown), and in the other case by inserting zig-zag portions of unequal lengths (Fig. 8, not shown). In a seventh embodiment, a windscreen lg, Fig. 9, comprises a T-shaped central conductor 36, 37, which extends from a terminal 38, and an associated U-shaped conductor 39a, 39b. The lower part of the U-shaped conductor comprises three parallel conductors 40a-40b, 41a-41b, 42a-42b. On one side, the three conductors 40b, 41b, 42b are connected in parallel. Before they reach the central conductor 36, they are connected to a conductor 43, Fig. 10, which is arranged around the terminal 38. The conductors 40a, 41a form branches having free ends, whereas the conductor 42a is connected at 47 to the conductor 43. The conductor 43 is extended by conductors 44, 45 arranged in a loop and connected at 46 to the central conductor 36. It is stated that when such an aerial is installed in a car radiation diagram minima in the fore and aft directions are improved (Fig. 11, not shown).</p> |
